Enlightened Cookery Part 2
When I was first introduced formally to biology in the 1950s it was widely felt at least among people at large and also by a great many scientists that science could and should be a search for irrefutable and even absolute truth. It was further widely supposed that cast-iron truth could and must be arrived at by strictly “rational” means; specifically, by rigorous experiment in strictly controlled conditions followed by equally rigorous analysis rooted in mathematics – for maths, it was felt, was ultimately “objective” and could not possibly be wrong.
Physics was taken to be the role model. In physics everything can be measured, very precisely, at least in theory; and whatever was intrinsically unmeasurable or too difficult to define, like, say consciousness or “mind”, was simply put to one side. Or, in the spirit of logical positivism, which was still going strong in the 1950s, whatever could not be firmly pinned down was felt to be a non-issue, muddying the waters, not worth serious thinking time, and should be excluded from the scientific canon or indeed from all thought. Those who dwelt on such matters were deemed to be woolly minded, and were duly banished from serious discussion (although some of very greatest scientists, including Max Planck, Albert Einstein, Paul Dirac, and Niels Bohr and his disciples, did wonder openly what truths might lie beyond the barricades of scientific rigour).
Indeed in science there was a hierarchy of respectability. Physics, strongly rooted in mathematics, was top; chemistry came next – very precise but not easy to reduce to terse mathematical formulae, such as E = MC-squared, as featured on many a tee-shirt. Biologists, who aspired to deal with the complexities of living bodies and entire ecosystems, were even further removed from the abstract certainties of physics. Biologists were said to suffer from “physics envy”.
So it was that the humble and specific science of nutrition was treated primarily as an exercise in biochemistry which in turn was an offshoot of organic chemistry; and the gut, like the body as a whole, was generally conceived as a machine, as had been recommended in the 17th century by Rene Descartes. (Though Descartes did not say that the body is a machine. As I understand things he simply said that for the purposes of study, it would be useful to conceive living creatures and their constituent organs as if they were machines. And this is indeed a useful approach – provided we do not assume that living bodies are nothing but machines, as has so often been done.)
Since the 1950s, however, science as a whole has relaxed. Hard-nosed logical positivism has died a death. More broadly, it has become obvious and more widely understood that big ideas of the kind we feel are important and true cannotbe reached by hard-nosed rationality alone. Einstein himself said as much in 1931 in Living Philosophies:
“The supreme task of the physicist is to arrive at those universal elementary laws from which the cosmos can be built up by pure deduction. There is no logical path to these laws; only intuition, resting on sympathetic understanding of experience, can reach them.”
In line with all this the science of nutrition has been transformed. The details of chemistry are supremely important of course but they can now be seen to be far more complex than was conceived, or at least as was taught, in the mid-20th century. And – more to the point – it has become obvious that the details of chemistry are only part of the story. To begin to get a grip we must spread the net far more widely.
The following is a somewhat impressionist account of the changes that have taken place over the few decades, at least as I have observed them. Some are simple changes of mind – theories have come and theories have gone. Some, more profoundly, are changes of mindset – of the way we look at the world; what the old Greeks called “metanoia”; and what the American philosopher of science Thomas Kuhn called “paradigm shifts”. So:
1: Sugar and Starch
In the 1960s the first serious doubts were raised around sugar and carbohydrates in general, primarily by the London-based nutritionist John Yudkin in his book Pure, White andDeadly, published in 1972. The doubts continue, not least around fructose, which combined with glucose makes sucrose, which is what most people call “sugar”. Among other things, fructose is said to upset the production of insulin whose job it is to regulate blood sugar levels, and this in turn may predispose to diabetes. In general it seems that the simple and related sugars glucose and fructose have very different effects on the body — which illustrates a more general principle that has often been overlooked: that the body is very discerning. It is alert to fine chemical distinctions and we cannot assume that it will treat two molecules in the same way just because we perceive them to be similar.
Good or bad, fructose derived from corn syrup is widely used as a sweetener, for it is indeed very sweet. Few, though, have many good words to say for sugar in general, although sweet foods are high in energy and surely should be good in the short term for anyone who is truly short of calories, which a great many people are, worldwide.
Others extended Professor Yudkin’s and others’ antipathy to sugar to embrace carbohydrates in general — including starch, the principal energy store of plants: macromolecules compounded from many molecules of glucose. People on low starch diets can still eat plenty of plants in the form of leaves and fruits but they miss out on what for most of humanity are the staples. Chief among these are the cereals (the seeds of grasses, (family, Poaceae, formerly called Gramineae); pulses (the seeds of legumes (Fabaceae, formally called Leguminosae)); and tubers such as potatoes and cassava. So a low starch diet by the standards of most of humanity is on the one hand very luxurious — generally high in meat, fish, and fruit; but it is also austere — no bread, no rice, no tortillas, no potatoes foods that for most people through most of history have formed most of the diet.
Some nutritionists and anthropologists have gone on to argue that the birth of arable farming, not long after the last Ice Age, was a huge nutritional mistake, even though it is widely seen to have given rise to modern civilization. Human beings simply are not anatomically or physiologically equipped, say the doubters, to cope with all that cereal. The “paleo diet” (where paleo is short for “Palaeolithic”) has enjoyed some vogue in recent years, based on the idea that our pre-agricultural, hunter-gathering ancestors must have got their calories from nuts, fruits, tubers, and the lean meat of wild animals, and not specifically from cereals. This idea appeals too to those, including many farmers, who are now reacting against the low-fat diets that were recommended in the 1970s and beyond and are now telling us that we should eat more meat and eggs and dairy. More on this later.
Whatever the benefits if any of the paleo diet, the theory on which it is based seems highly speculative, not to say flimsy. I have written a lot about human evolution in my time and the widely accepted theory, backed by a great deal of fossil and geological evidence, is that our australopithecine ancestors broke away from the other apes as the world grew cooler and drier in the late Miocene and early Pliocene, and they left the dwindling forests of southern and eastern Africa to make their living on the savannah. There presumably they ate whatever plants were growing and whatever animals they could catch — but animals are elusive, and fight back. Savannah basically is grassland and grasses were abundant, not to say dominant, and our savannah-dwelling ancestors must surely have eaten their seeds. Cereals too are the seeds of grasses so why are we supposed to be so ill-adapted to them? Particular indispositions such as gluten intolerance are surely caused by modern high-gluten cereals and modern processing rather than by cereals per se. Besides, in his excellent book TheDiet Myth (Orion Publishing 2015) Professor Tim Spector points out that even if we were ill-adapted to eating cereals 10,000 years ago (a very big “if”), we have had plenty of time to adapt. Favourable mutations are not common but they do happen and westerners on the whole have for example adapted to lactose, the sugar in milk, even though our ancestors did not retain the enzymes needed to cope with it after they had passed infancy.
In short, common sense and evolutionary biology suggest that a high cereal diet should be perfectly good (although the special case of gluten intolerance seems to need far more research than it is getting). The idea that bread, made mainly from wheat, is the staff of life (plus rice, maize, oats, barley, rye, sorghum, and millet) seems to have served most of the human species pretty well over the past 10,000 years. There is a lot wrong with modern diets but surplus of cereals per se does not seem high on the list.
Overall, though, the general position on carbohydrates remains unresolved, not to say confused. Some advisers in evangelical vein condemn sugars and starch out of hand — yet for some health food shops, variations on a theme of cereals (muesli, wholemeal bread, and mixed loaves of wheat, barley, and rye) are the stock-in-trade. There’s something wrong somewhere. (Quinoa and buckwheat are non-cereal grains. Quinoa is placed in the genus Chenopodium alongside Good King Henry and Fat Hen, within the goosefoot family Amaranthaceae; and buckwheat is related to Dock, in the family Polygonaceae.)
2: Protein
In the decades after World War II until well into the 1970s it was widely believed and taught that human beings need to eat loads of protein to keep us in best health — around 15% of nutrient intake, measured in calories. Furthermore, the protein had to be “first class” — containing the complete spectrum of amino acids that humans need. Such a target could be met only by eating the flesh of animals. Of course, plants supply protein too – but not usually enough, it was felt, and rarely of sufficient quality. Most plant protein was deficient in one or more of the essential amino acids, and was duly said to be “second class”. Since most people worldwide did not have access to copious supplies of meat, it was widely supposed that most people must to some degree be protein-deprived and that the world as a whole must be experiencing and suffering from a “protein gap”. In particular the Swedish-American scientist and geographer George Borgstrom spread this message in scholarly detail in The Hungry Planet (1965). In 1969 he followed this up with Too Many, in which he argued that humanity had out-grown its food supply, just as T R Malthus in the late 18th and early 19th century predicted we were bound to do. I read both books assiduously.
The idea that we all need to eat a lot of protein and of the supposed protein gap sprang from research in Africa dating from the 1930s – research that was interrupted by World War II and left unfinished. This research seemed to show that kwashiorkor, the form of malnutrition that leaves children with swollen, oedematous bellies was caused primarily by lack of protein; and from these specific observations the idea grew up that all of us, ostensibly malnourished or not, were likely to be short of protein. Indeed in some circles, even back in the 1930s, the idea that we need a significant meat intake and that plant protein won’t do became something of a fetish in some avant garde circles (following hard on the heels of the vogue for eugenics). John Steinbeck parodied this trend in Tortilla Flat in 1935 in a passage about a paisano (peasant) lad called Alfredo, aka Freddie:
“At about this time in California it became the stylish thing for school nurses to visit the classes and to catechize the children on intimate details of their home life. In the first grade, Alfredo was called to the principal’s office, for it was thought that he looked thin. The visiting nurse, trained in child psychology, said kindly: “Freddie, do you get enough to eat?” “Sure”, said Alfredo. “Well, now. Tell me what you have had for breakfast.” “Tortillas and beans”, said Alfredo. The nurse nodded her head dismally to the principal. “What do you have when you go home for lunch?” “I don’t go home.” “Don’t you eat at noon?” “Sure. I bring some beans wrapped up in a tortilla.” Actual alarm showed in the nurse’s eyes, but she controlled herself. “At night, what do you have to eat?” “Tortillas and beans.” Her psychology deserted her. “Do you mean to stand there and tell me you eat nothing but tortillas and beans?” Alfredo was astonished. “Jesus Christ”, he said, “what more do you want?”
Before World War II too it became possible to “fix” vast quantities of nitrogen via the newly industrialized Haber process – combining nitrogen gas with hydrogen to make ammonia which could then be oxidized to make nitrate. Nitrate was in huge demand in the war to make explosives – and after the war when the demand eased off the nitrate that was no longer needed to make bombs could be turned into agricultural fertilizer, and the otherwise largely redundant manufacturers of explosives duly obliged. So yields of grass and cereals wondrously increased and America in particular suddenly felt empowered to close the supposed protein gap with vast quantities of beef and pork, fed on highly fertilized ryegrass bred specifically for grazing, and on cereals and some soy. Chickens too were raised by the billion on cereals and soy, increasingly in the still novel and eminently “rational” batteries. I was told when I first went to the US in the 1970s that transport cafes in Texas had been offering 16- or 32-ounce steaks with eggs ad lib to the 25-stone truckers who were their principal clientele. The truckers rather unsurprisingly tended to die young. Back in more frugal Britain steak and salad became the standard health-conscious businessman’s lunch (there weren’t many businesswomen in those days). Those who couldn’t afford steak made do with hamburgers. On children’s television in the 1950s and ’60s we were encouraged in effect to eat as much meat, eggs, and cheese as was available. Breakfast cereals and even bread were said only to supply “empty calories”.
The passion for meat was not driven only by nutritional theory. Steak and burgers and Kentucky Fried are the archetypal fast food. They don’t require serious and expensive culinary skill – which cut the cost of catering wonderfully. So it was that nutritional lore, big-time industrial agriculture, and a very profitable line of catering meshed together beautifully, and profitably. And as Alfredo said in a somewhat different context, “What more do you want?”
But in the 1970s people (including me) began seriously to question not least on common sense grounds whether we really do need all that meat and fish, and whether there really is a specific and widespread “protein gap”. After all, if things were as bad as George Borgstrom was suggesting then most of humanity would be on its knees, which clearly wasn’t the case. Some of the world’s most famous intellectuals were or had been vegetarians or indeed vegans, including Leonardo and George Benard Shaw. So too was the great Afro-American athlete Jesse Owens who won four gold medals at the 1936 Olympic Games in Berlin, prompting Hitler to stomp out in a huff. And so were vast numbers of Asians, not least in Japan and various states in India.
In particular, various nutritionists including the Indian nutritionist and statistician Pandurang Vasudeo Sukhatme (1911–1997) began to show that all the major cereals that are the world’s staples – wheat, rice, maize, oats, barley, rye, sorghum, millet, and non-cereal grains like buckwheat and quinoa, and of course the pulses – contain easily enough protein at least to sustain a healthy adult. Potatoes too provide significant amounts. Indeed the Irish peasants of the early 19th century, and I believe in parts of mainland Europe, subsisted almost exclusively on potatoes, until the blight wiped out the crops in the 1840s. Obviously this is far from ideal but it shows what is possible.
True, plant protein does not usually contain the complete spectrum of essential amino acids in the right proportions. In particular, cereal protein tends to be low in lysine. But the protein in beans and other pulses is typically rich in lysine so pulses and cereals together provide all that’s needed. Alfredo’s apparently exclusive diet of tortillas (made from maize flour) and (kidney) beans (of the genus Phaseolus) leaves something to be desired but it is not specifically low in protein as the visiting nurse obviously supposed. Indeed the cereal-plus-pulse theme runs through nearly all the world’s traditional cuisines: tortilla with beans; chapatis with dahl; tofu and rice; beans on toast. If we eat enough of such provender to meet our energy requirement then the protein will take care of itself.
Science is indeed vital but it does not always or necessarily improve on traditional practice. Sometimes – often – it tells us that the traditional ways were right all along, That grains and beans (and nuts and some tubers) provide us with all the macronutrients we need is a paradigm shift of the greatest significance. It suggests that all of us could indeed eat well, if only we re-learned how to cook and if the world’s leaders put their minds to the world’s real problems.
Yet all this does not mean that there is no need for livestock. Far from it. One of the outstanding agriculturalists it’s been my privilege to know was E R (“Bob”) Orskov, first at the Rowett Institute and then at what is now the James Hutton Institute, both at Aberdeen. He grew up on a small traditional farm in Denmark, handling heavy horses at the age of six (although, he said, the horses handled him) and became an internationally renowned animal nutritionist who spent much or most of his working life among traditional farmers in Asia, Africa, South America, and the Caribbean.
Prof Orskov (as he became) liked to point out that for peasant farmers – meaning most farmers — and their societies the world over, animals are essential. They can often be raised on land that is too dry, wet, cold, steep, rocky or salty at least for mass production of conventional crops. Though livestock need not and usually should not be the prime source of protein they do supply various more recondite nutrients or supplements that might otherwise be in short supply including zinc and calcium and some unsaturated fats and (I would guess) cryptonutrients, of which more later. In traditional societies too they may still provide the most affordable and convenient transport. Horses are essential players in eco-friendly forestry, dragging out the logs without damaging other trees. Cattle dung the world over does excellent service as the daub in daub and wattle and in India in particular dung is indispensable fuel. Long-lived dairy cows in particular are excellent companions too. Part of the family indeed.
In short, livestock should not be the prime focus of agriculture, as it has so often become. We surely should not be feeding more than 40% of the world’s grain and about 80% of the soya to cattle, pigs, and chickens as we do now, or felling vast areas of rainforest for grazing or for growing cereals and soya specifically to feed to livestock, simply or primarily for profit that in practice serves primarily to make rich people richer. That is somewhere between folly and sacrilege. But livestock judiciously raised is or are very important or indeed essential players in world agriculture nonetheless.
I was also able in the late 20th century to talk at length to N W Pirie, physiologist and virologist at Rothamsted who, among much else, promoted the idea of extracting protein directly from green leaves. Pirie pointed out that all the world’s greatest cuisines use meat sparingly, primarily as garnish. The Chinese make wondrous meals from copious rice and pak choi cabbage with just a few slivers of fatty pork, and plenty of soy sauce. (I always remember a local café in China with a dustbin full of boiled rice in the middle from which the clientele helped themselves, and a couple of fat hogs out the back, fed largely on leftovers. In a sensible world, I suggest, every restaurant would have chickens or pigs out the back to wax fat on the leftovers. A huge amount is otherwise wasted. Westerners in general evidently throw away about a third of their food after it leaves the kitchen.)
I would add that meat is also used traditionally as stock, as in many a variation of risotto; and for occasional and/or ceremonial feasts, in which we might include the traditional British Christmas goose and the Sunday roast.
Traditional cuisines also make use of the whole animal. Lung is a traditional constituent of haggis, together with oats, and why not? A good haggis is a wondrous thing –
“Great Chieftain o’ the Puddin-race!”
— as Robert Burns observed. (I do feel though that his comments on some other cuisines were somewhat too chauvinistic:
“Is there that owre his French ragout,
Or olio that wad staw a sow,
Or fricassee wad mak her spew
Wi’ perfect sconner,
Looks down wi’ sneering, scornfu’ view
On sic a dinner?”
I like a good ragout myself, with loads of pasta (and greens)).
Pig’s trotters are excellent fare too. As the net informs us,
“Eisbein mit Sauerkraut ist ein absoluter Klassiker der deutschen Küche”.
Quite right. And as I have recorded before, one of the most memorable meals I ever had was of tripe, cooked Mediterranean style, in Sienna.
All in all it seems doubtful whether a livestock-free agriculture could really “feed the world”. It surely would not be ideal ecologically. I am not a vegetarian but, like many other people, I nonetheless feel it is a somewhat shocking thing to raise sentient creatures specifically for slaughter but if the animals are raised kindly and with proper respect for their own psychology (a big if!), then this seems the least bad option. And sometimes we have to settle for the least bad. Livestock farming truly becomes bad and indeed may be positively evil when there is too much of it, and when the prime or the sole motive behind it is the desire to maximize (short-term) material wealth. But this of course in the modern neoliberal world is largely the case. But then, the same might be said of all human activity, down to and including AI or indeed football. Enlightened Farming and enlightened cookery should be should be the ultimate “appropriate technologies” as E F Schumacher envisaged in the early 1970s. But over-productive agriculture geared to profit is far from enlightened.
In short, it is a huge mistake – ecological, economic, moral, aesthetic, gastronomic – to make meat the centre-piece of every meal as seems to have been the ambition in the western world for the better part of the past century. But to go to the other extreme and banish meat or even dairy altogether is not ideal either. To raise animals kindly in ecologically conservative ways and make the best possible use of the meat, milk, and eggs that they provide seems to be as good as we can reasonably hope to achieve.
3: Fat
In the mid-20th century coronary heart disease (CHD), caused by blockage of the coronary arteries which feed the muscles of the heart itself, was on the rise, particularly among middle-aged men. In the US, Finland, and Scotland in particular CHD was reaching epidemic proportions. The blockage is caused by “plaques” of fat which build up on the artery wall, and typically become calcified (chalky). Each plaque is called an “atheroma”, plural “atheromata”. People thus affected are said to suffer from atherosclerosis, or hardening of the arteries.
Starting in earnest in the late 1940s, large-scale epidemiological studies began to show beyond what seemed to be reasonable doubt that CHD correlates strongly with fat intake. In a nutshell (and of course without wishing to stereotype), Americans, inspired not least by their zeal for protein and enjoying their new-found, post-war, post-depression affluence, were eating too much steak and too many burgers and doughnuts (aka donuts). The Scots, so it was widely supposed, liked to fry everything and shunned vegetables (even though Scotland has some of the finest horticulture in the world). The Finnish diet leaned heavily on dairy. Of course there were many putatively compounding variables (eg, the Scots smoked a lot) but the correlation seemed plain to see.
Contrariwise, people with a low fat intake had far fewer heart attacks and the Japanese whose traditional diet was very low in fat had virtually no CHD at all – although they did suffer many more strokes than the global average, perhaps because of their high salt intake. Of course, “correlation is not cause”, but research of a physiological kind strongly suggested that indeed, eating too much fat can and does indeed damage the arteries. Genetics presumably played a part too – but Japanese people who had moved to California did have heart attacks and in Italy, the people of Bologna to the north, who ate a fair amount of meat, had significantly more heart disease than the Neapolitans of the south, who ate far less meat and more fish (and a great deal of pasta).
Inevitably the research grew more and more complicated (because life is complicated) but the whole emerging thesis was brilliantly summed up in 1976 in a report by Britain’s Royal College of Physicians which I studied assiduously, called Prevention of Coronary Heart Disease. And although a great deal more is known now than in the 1970s the physicians’ broad recommendations have stood up remarkably well.
In a nutshell, the RCP concluded that affluent westerners should indeed eat less fat. Specifically, the Brits, Americans, Australians and their like on average acquired around 40% of their calories from fat, while the Neapolitan diet was only 20% fat and the traditional Japanese diet was down to 10%. The physicians acknowledged that the Brits as a whole would not switch easily to a South Italian diet and still less to a traditional Japanese diet but, they said, as a reasonable, commonsensical compromise, we should all try to get down to 30% fat or lower.
It was clear, though, that not all fat is the same, and different fats may have very different effects on the human body. Thus the bulk of fats in the diet are triglycerides – three chains of fatty acids joined to a molecule of glycerol, aka glycerine, which is classed as a “sugar alcohol”. The fatty acids are chains of carbon atoms with hydrogen atoms on each side – chains of CH2s, in fact. Each chain culminates in a carboxyl radical with the formula COOH.
Within this simple formula there is endless scope for variation. The chains vary in length from 4 to 28 carbon atoms. In some triglyceride molecules the three chains are all the same while others combine chains of different structures. Such differences may seem trivial yet can be very significant nutritionally.
It seems too in this and many other contexts, that what we were given to understand at school in the 1950s was wrong. Fats, proteins, carbohydrates are not broken down exhaustively in the gut into their constituent lipids, amino acids, and sugars, so the form that food takes can matter a great deal, and in any case the body can be remarkably discriminating and different lipids or sugars that seem to be very similar chemically may have significantly different effects. Just to complicate things further, for various reasons, different individuals may respond to the same ingredients differently. I suppose in the end, in theory, it should be possible to “reduce” the science of nutrition to organic chemistry, and chemistry is or can in theory be an exact science. But within the context of a living body the chemistry can take us in endless directions, and ultimately is beyond exhaustive analysis. So in the end, in practice, we have to be content with generalisations. If the generalisations are good enough it does become possible to make broadly sensible recommendations that apply more or less to everybody, or at least apply to particular groups, as in middle aged men or young women. But the devil remains in the detail nonetheless.
In particular, the fatty acid chains in triglycerides differ in their degree of “saturation.” Thus, carbon atoms in general can attach to – or “bond” with – four other atoms. In a carbon chain each carbon uses up two of its bonds by attaching to its neighbouring carbons. This leaves two bonds per carbon sticking out on either side. In a fully “saturated” fatty acid chain the two spare bonds are both occupied by hydrogen atoms (which in practice are ultimately derived from water, which as everyone knows is H2O. Two Hs and one O per molecule). But sometimes some of the spare bonds are not occupied by hydrogens, and the bond that is left unrequited instead forms a “double bond” with the neighbouring carbon. Fatty acid chains that do not carry all the hydrogen atoms they could theoretically accommodate are said to be “unsaturated”. Those that lack two or more hydrogen atoms are said to be “polyunsaturated”.
In general, the fat of terrestrial mammals tends to be saturated – and saturated fats tend to be “hard”, as is very obvious in suet. Chicken fat, however, contains far less saturated fat than the red meat of cattle and sheep. Polyunsaturated fats are softer and indeed oily, as found in plant and fish oils, as alluded to earlier. Olive oil contains a mixture of unsaturates, the chief of which is oleic acid which is “monounsaturated”: there is room in oleic acid molecules for only one more hydrogen. Oleic acid also occurs in animal fats, including chicken fat and indeed lard, which is “rendered” pig fat (meaning fat that has been melted free from connective tissue).
To cut an overlong and somewhat intricate story short, it seems that whereas saturated fats seem to exacerbate atherosclerosis, polyunsaturates do not, and may indeed be protective. So to the general advice – cut fat intake from 40% to 30% — the physicians further advised us all to switch as far as possible from saturated fat to unsaturated. They drew special attention to sunflower oil and the much less common safflower oil, and to olive oil. In in other words, they did not specifically advise us all to become vegetarians but they did advise us to adopt a “Mediterranean” diet: low in meat and high in plants. The Mediterranean diet as eaten in Naples does tend to include a lot of fish too of course, and molluscs and decapod crustaceans, which may be highly desirable to eat from a nutritional point of view but can be ecologically disastrous. Some nutritionists argue that fish oil, rich in omega-3 fatty acids, is essential for optimum brain development. But since many outstanding intellectuals grew up in the uplands of India many miles from the sea and with never a whiff of fish, it seems that plant oils can do what’s needed on their own.
The RCP warned in their report that the evidence they presented to support their recommendations was not cast iron and could not be one-size-fits-all but what they expressly called “the balance of probabilities” points towards a more Mediterranean or indeed more Asian style of eating. Fifty years later, their general thesis still seems to stand up. It matches the evidence and it feels right, and we should not lightly discard our intuitions in such matters.
There are a few refinements however. First, it seems that the fat of game animals such as deer, and — of more practical importance – the fat of cattle that have been pasture-fed contains more unsaturated fatty acids than the fat of cattle that have been raised largely on grain and soya-based concentrates. Graham Harvey drew particular attention to this in Grass Fed Nation in 2016. Sheep, traditionally seen as the poor relations, tend to be pasture-fed, or nearly so, as a matter of course. If we raised cattle and sheep more or less exclusively on pasture then we would of course produce far less than we do now, when cereals and soya are grown on a vast scale specifically to feed them. So if we raised cattle and sheep more or less exclusively on natural diets then that alone would take us into the realms of the Mediterranean diet; and since the fat of those animals should be more unsaturated, that would be even better. So here again is a wonderful correspondence between agroecological farming and sound nutrition.
But then, the correspondence is in line with Dobzhansky’s observation that all biology reflects the outworking of evolution (and indeed of ecology). After all, agroecology seeks essentially to emulate wild nature, and the human lineage obviously evolved in the wild, and became more and more specifically human over several million years. Our ancient ancestors clearly evolved as omnivores, generally with a heavily plant-based diet, although with meat when the going was good; and the animals our pre-agricultural ancestors caught and ate would of course have eaten a natural diet, eating only what nature laid on in their immediate surroundings. The meat from those prey animals would have been less fatty than the usual modern supermarket kind, and what fat there was on it would have been less saturated. Wild chimps, it’s now known, like a bit of hunting too – largely focused on monkeys, who they are wont to tear limb from limb. And although gorillas are commonly presented as virtual vegans, the founder of Howlett’s and Port Lympne zoos in Kent in the 1970s, John Aspinall, used to treat his famed colonies of Mountain Gorillas to roast legs of lamb at weekends, which were much appreciated. Chimps, bonobos, and gorillas are our closest relatives, grouped with us within the subfamily Homininae. Omnivory, albeit plant-orientated, is very much a hominine thing. The whole story fits together beautifully. And it all accords with the nine-word summary:
“Plenty of plants, not much meat, and maximum variety”
4: From Roughage to Fibre
“Roughage” too underwent a serious overhaul from the 1970s onwards, and re-emerged as “dietary fibre”. There were significant advances on three fronts. First, physicians such as Denis Burkitt and Hugh Trowell perceived that the people of Africa in particular on a traditional, plant-oriented, high-fibre diet suffered none of the “diseases of affluence” that were besetting the affluent world – not just CHD but also various cancers, diabetes, and indeed gallstones, all exacerbated by obesity. And, they suggested, fibre could be protective.
Secondly, botanists and nutritionists alike pointed out that plant cell walls do not consist solely of cellulose, which does tend to be “inert”, but also include a host of “hemicelluloses”, which incorporate some recondite sugars; and also pectin, which is described as a “hereropolysaccharide”. (Its molecules are compounded of various sugars and other things as well.) All of these could be broken down to some extent by the microbes in the colon and then became active players. Clearly, too, not all plant fibres are chemically or physically the same.
Thirdly, by then it had long been obvious that the colon is not merely a conduit, tasked with returning the remains of previous meals to the wider world, but is a vital player in the whole digestive and absorptive process. Among other things, bile salts, squirted into the gut from the liver to assist the digestion of fat, are resorbed by the colon, and re-used. But they are also altered chemically in the colon — and the ways in which they are altered depend in part on the amount and on the particular nature of any fibre that’s present. Bile salts are stored in the gall bladder and some kinds of bile salt are more likely to cause stones than others, so here was a possible physiological link between dietary fibre and gallstones.
As long as fibre was seen as “roughage”, a built-in pan scourer, it was hard to see how it could influence the various diseases with which it was being associated. But once it was called “fibre” and recognized as an active player in the metabolism of the gut, the whole fibre story became, not proven, but eminently plausible; and plausibility is the start of serious interest.
5:Cryptonutrients
Food isn’t just nutrients: materials that build flesh and bones and brains, and/or provide fuel for energy. It also includes agents that behave more like pharmaceuticals or tonics, helping the works to run more smoothly. These include the vitamins, which are known to be essential, since deficiency leads to disease and death.
But in the 1990s it began to seem that there could be and probably is a whole host of subsidiary agents that if not necessarily vital are at least beneficial; agents that are somewhere between a nutrient and a tonic. The pharmaceutical industry seized on this idea and called these quasi-hypothetical agents “nutraceuticals”. The food industry called them “functional foods”. Plant sterols are an example. They are chemically similar to cholesterol but, evidently, they help to lower cholesterol levels in the blood. My own contribution to this discussion, written up here and there, has been to class all these subsidiary agents as cryptonutrientsand to suggest an evolutionary reason why there should be such things. (I gave a talk on this at the Royal Society no less, and it went down well.)
To begin at the beginning: human evolution did not begin when our apish ancestors took to the plains. It began long before our ancestors were human at all-with the origin of life on Earth, 3.8 billion or so years ago. After all, we still share some biochemical pathways and the corresponding genes with our fellow mammals and with vertebrates in general. Evolutionary biologists commonly point out that we have inherited many of the features that enabled our australopithecine and early hominine ancestors to survive the Pliocene and Pleistocene but we have also inherited at least some of the adaptations that enabled our fishy ancestors to survive in Palaeozoic times. Indeed, we still retain a fair slice of the genes and metabolic pathways that are common to all animals and even to microbes.
Through all those millions and billions of years our ancestors must have been assailed with many thousands of different chemical entities, some of them produced by plants and other organisms for the express purpose of keeping predators at bay; in other words, toxins. Other such agents arose simply as by-products. Notably, oxygen gas appeared in the atmosphere as a by-product of photosynthesis. Our ancestors had to adapt to this relentless chemical assault. Sometimes, presumably, they just avoided trouble. They just didn’t eat things that they “knew” to be harmful. Often they evolved mechanisms of detoxification. But often, too, they went one step further and evolved the means to make positive use of the extraneous chemical agents that hitherto had harmed them. Oxygen is a case in point. For organisms that cannot cope with it, it is the mother of all toxins precisely because it is so chemically active. For creatures like us, who can cope with it, it has become vital — its chemical potency turned to advantage as the supplier of instant energy. Even so, our bodies are packed with “anti-oxidants”, including some of the vitamins, to deal with rogue oxygen that escapes the normal coping mechanisms.
The cryptonutrients, I suggest, arose as agents in the environment, generally produced by other species, that our ancestors were obliged to deal with and which, as their evolution progressed, they turned to advantage. The vitamins can then be seen to be cryptonutrients on which we have come to rely more or less absolutely, so they too have become vital. The rest, possibly many thousands of them, may well be good for us, but the effects are generally too small to notice or to quantify. A regular dose of cryptonutrients – a plant sterol, for example – may well add two years to a life that is already long. But it would be very difficult in practice to demonstrate such an effect. Such an effect would not show up for example in a six-week trial on laboratory rats.
Overall however, we can be sure that cryptonutrients of many kinds are very important. But there are probably a great many of them, and the effects of any one may be very difficult to pin down and surely must vary from person to person. It seems very reasonable to suggest in a general way that a very varied diet based on natural ingredients is more likely to contain the required range of cryptonutrients than an artificial diet which on the whole will be simplified. Those who advocate natural diets are likely to be accused of “muck-n-mystery” — but to a significant extent that may be the best we can do. It is the case too, of course, that modern diets full of processed foods tend to contain a wide range of additives — some of which do not occur in nature so our ancestors had no opportunity adapt to them. They could conceivably do us long term harm that is not easily measurable and stays below the radar, just as the hypothetical cryptonutrients may bring long-term benefit.
In short, taken all in all, it’s clear that in reality, nutrition cannot be an exact science. Physics is not always an appropriate role model.
The modern understanding of dietary fibre and the idea of cryptonutrients also lead us very nicely into one of the greatest of all insights in the history of nutritional science — a paradigm shift of monumental significance. This is the realisation that the gut microbes are not just spivs or uninvited lodgers. They are, for all animals, essential allies. True, our alliance with gut microbes breaks down from time to time, as all alliances are prone to do. But the microbes are essential nonetheless.
6: The absolute importance of the gut microbes
I was brought up as was usual in my childhood days to be afraid of “germs”. Polio, a virus, was the great fear in the middle years of the 20th century. Measles, another virus, was seen largely as a routine childhood ailment although it was a prime cause of infant mortality in parts of the tropics and was the main cause of non-congenital blindness and deafness in the west. There were plenty of nasty bacteria too, including TB which mainly affected the poor and malnourished, and mothers still lived in fear of whooping cough and diphtheria. Hygiene was stressed. Food poisoning could kill too and the most minor cuts could lead to blood poisoning. Penicillin was produced on the mass scale only in World War II and some years passed before it was available more or less universally. All bacteria and indeed all microbes tended to be classed as germs and were commonly seen to be seriously bad news. We had to put up with the ones that were known to thrive in the gut but mainly, it seemed, because there wasn’t much we could do about them.
This kind of mentality lives on. Young mums on daytime television are still being urged to spray their kitchens and their children’s high-chairs with disinfectant. The message still goes out that our and our children’s surroundings should be as sterile as possible; one big intensive care unit. There was even a vogue in the 1960s for germ-free piggeries.
Even in my far-off schooldays, however, the story was not entirely negative. Industrial microbiology has flourished since the 19th century (Louis Pasteur was a seminal figure) and its triumphs include the control of fermentations of all kinds from bread to cheese to wine and beer. Before World War II Albert Howard introduced the world to the modern age of composting which of course is primarily an exercise in fungal and microbial decay. The essential role of mycorrhizas in extending the range of roots was known since the 19th century, and so too the role of Rhizobium bacteria in legumes in fixing nitrogen.
All such observations helped to lay the ground for what is perhaps the most significant nutritional insight of the past few decades: that the microbes in our guts are our partners, mediating between us and the world at large, and at least in net are our benefactors. To a mostly unknown but certainly to a very large extent the gut microbes determine how we respond to any particular kind of food; whether or not it makes us fat; whether it makes us ill or does us good. The differences in the ways in which different individuals respond to particular foods or indeed to entire diets can at least in part (probably in large part) be ascribed to differences in their gut microbiota; and those differences in turn probably reflect differences in previous diet. Indeed, as outlined below, the way that different people respond to the same food may reflect differences in childhood experiences, not least around the time of birth. They might even reflect the microbial status of our mothers – or indeed our grandmothers. The shortcomings of our ancestry cannot necessarily be made good in one generation.
Antibiotics and food additives or novel foods of the kind cooked up in the laboratory can alter the gut flora dramatically. Again, the general idea from health food buffs that natural food is generally good and artificial food is likely to be bad begins to seem highly plausible, although it is still mocked in some circles of commercial science. Two anecdotes from Tim Spector’s The Diet Myth make the point.
The first involves identical twin sisters. One was prone to put on weight and was forever dieting, while the other stayed forever slim. They were genetically identical, so why the difference? The answer, apparently, was that their gut flora was very different — and the reason for that, it seems, is that they were born by Caesarean section. Babies born by the natural root pick up bacteria from the birth canal and general nether regions of their mother – but babies born by Caesarian section have no opportunity to do so. Furthermore, after they were born, the babies were handled by different nurses. Each nurse passed on her own microbiota to the particular baby in her charge. The microbiota of the two sisters remained very different into adulthood.
Spector also tells of an American doctor who, to get around this problem, wiped a swab around the relevant areas of his wife when she gave birth by Caesarean section, and then applied the swab to the face and mouth of the newly emerged baby. So far all is well and some Scandinavian hospitals have unofficially adopted the swab technique as standard practice in Caesarean birth. It’s becoming fairly common practice too to enrich impoverished gut microbiota with faecal implants from other peo-ple. We have come a long way since my schooldays, when bacteria were just “germs”.
The parallels with organic farming are obvious. Both recognize the supreme importance of microbes. Above all, it seems, it is essential to maintain their diversity. At least as a rough rule of thumb it seems that in the gut, as in a tropical forest or on a farm run on agroecological lines, the greater the diversity the better. The diversity of the gut microbes can be encouraged with “prebiotics”, which typically means mixtures (as mixed as possible) of bio-chemically various plants-herbs, nuts, recondite roots. Impoverished gut floras are enriched by adding “probiotics”: suites of new microbial species as contained for example in active yoghurt or real cheese, or fermented plants including miso and sauerkraut (and of course with faecal implants). The whole procedure is hit and miss but it surely must be taken seriously. In fact, says Professor Spector,
“You won’t go wrong if you just treat your own microbes like you would treat your own garden. Give them plenty of fertiliser – prebiotics, fibre, and nutrients. Plant new seeds regularly in the shape of probiotics – foods that already contain useful bacteria. Give the soil an occasional rest by fasting. Experiment, but avoid poisoning your microbiotic garden with preservatives, antiseptic mouthwashes, antibiotics, junk food and sugar”
Finally, the growing appreciation of gut microbes and microbes in general adds weight to the cryptonutrient idea. It’s a fair bet that most of the peculiar chemical agents to which our human and pre-human ancestors were obliged to adapt were and are microbial in origin. Oxygen certainly was. Cyanobacteria (known in earlier times as “blue-green algae”) invented photosynthesis. Plants acquired the skill by turning cyanobacteria into chloroplasts (or so all the evidence suggests).
Clearly, there has been much confusion in nutritional science this past half century, and there still is. As Spector says, while some nutritionists advise us to nibble more or less continuously (“grazing”), others recommend a few big meals. Over the past 30 years, too, “almost every component of our diet has been picked on as the villain by some expert or other” and yet “our diets continue to deteriorate”. The focus is largely on losing weight, yet the average western waistline continues to expand by about an inch per decade and there’s evidence that repeated dieting may make people fatter. Two generalizations that seem to make sense are, first, that most diets are monotonous, and a surfeit of grapefruit or cabbage soup (one of Spector’s examples) suppresses the appetite wonderfully. Secondly, the many and various dietary adventures affect the microbiota in ways that are not understood, with consequences that are equally mysterious — but in the light of what is known, seem eminently plausible.
In short, in nutrition as in farming (did the powers-that-be but realise it), the greatest of all the paradigm shifts of recent decades is the rise and rise of microbiology. It’s clear now in all contexts that microbes are not just freeloaders, competing with us for nutrients. They, more than any living creatures, make the world the way it is — the soil, the air, the state of the sea, our own nutritional status. They are the great intermediaries, between us and the universe at large. Instead of zapping them willy-nilly, spraying kitchens with disinfectant and generally trying to turn our surroundings into an intensive care unit, we need to open an intelligent dialogue with them. As Eve Balfour said when she founded the Soil Association in 1944, look after the soil and the plants will look after themselves — it is clear care for the soil in very large part means care of the microbiota. Now we can see very clearly that the same principle applies to the gut. If we want to be as healthy as we can be, we must nurture and cultivate or at least not unduly molest our on-board microbes.
One last, very big caveat. We learnt at school in the 1950s that microbes can turn nasty and cannot be taken lightly — and Covid-19 has rubbed that lesson home all too emphatically. So on the one hand we need to acknowledge that microbes are key players in the world’s and own internal ecology, and strive as far as possible to forge a symbiotic relationship with them; not assume a priori that they are the enemy and contrive to live in a sterile bubble. But we cannot afford to be cavalier. Microbes of all kinds may still do immense harm, as illustrated not least in recent years by Covid and Ebola. In our relationships with the world’s microbiota we, and all creatures, must tread a narrow path.
Even more strikingly, research over the past few decades has challenged and to a significant extent reversed an idea that has been at the heart of biology, a virtual dogma, since the 1890s – a paradigm shift indeed. Thus:
7: Epigenetics
In the mid-20th century it was generally assumed that our genes are virtual despots, loftily issuing orders from the security of the cell nucleus. Now it is clear that the genes of all organisms are very responsive to the circumstances: to the cell around them, which in turn is tuned in to the whole organism, which in turn must respond to the world at large. The past decade or so in particular has seen the rise of epigenetics — ad hoc mechanisms that turn particular genes on and off and thus change the behaviour of the genome, sometimes in the short term, sometimes through a whole lifetime, and sometimes over several generations. So it is clear now that the way we respond to food, and whether or not for example we became fat or stay slim, depends in part on our own diet in infancy, in part on our mother’s diet when we were in utero; and the way our mother doles out nutrients to her foetus depends in part on her own experiences in infancy, and in utero; and all these influences are mediated via the genes.
As Nessa Carey describes in The Epigenetics Revolution (Icon Books, 2011), all this is illustrated wonderfully by the Dutch Hunger Winter from November 1944 to late spring 1945 when the war prevented food imports into Holland. Many starved and many of the survivors were permanently affected — like Audrey Hepburn, sixteen at the time, who remained thin (or enviably slim) though rarely in good health through all of her some-what foreshortened life. Others were in utero at the time, and for some weeks or months were deprived of nutrient as their mothers went hungry. If women were already pregnant by the time the hunger began, so that their foetuses were well fed in the first months and then deprived, their babies were likely to be born small — and they tended to stay small throughout their lives, and were not so likely as the rest of the population to grow fat. The foetuses of women who conceived towards the end of the famine were deprived in the first months of their gestation but then were well fed –and then, generally, they caught up, and at birth were of normal weight. They, though, were more likely than usual to be obese in later life and also suffered other problems of health. Truly intriguing, however, is that some of these effects lasted into the following generation. That is, the grandchildren of the women who were starved in pregnancy also tended to be small, or else to be more than usually prone to obesity and ill-health. The inference (for which there is much independent evidence) is that epigenetics was and is the cause. Malnourishment in the womb did not cause the genes of the foetus to mutate, but it did impose epigenetic controllers onto some of the genes which altered their behaviour — and the effects continued after birth and into the next generation.
That is just one example of the power of epigenetics. Nessa Carey is right to speak of the “epigenetic revolution.” Presumably, the gut microbiota is involved too. The gut flora of women starved in late pregnancy must surely have been affected. Perhaps the microbes themselves cause at least some of the epigenetic effects. We might assume, too, that the interaction between the genes and the microbes is two-way. Microbes and their hosts are in constant dialogue, each responsive to the other. All in all, the narrative of nutrition grows richer and richer.
Put all this together and the Cartesian model of the body-as-machine seems most inappropriate. Wind up the clock, stoke up the boilers, press the right levers, and a machine will behave exactly as it is designed to behave. But the bodies of living creatures are not machines. They are intelligent beings. Even those that don’t have brains behave as if they were intelligent. Even trees have their own agenda, and how they respond to any one stimulus is conditional. It depends on what else is going on — whether it’s spring or autumn, for example: time to grow or time to shut up shop. For animals, each individual molecule imbibed is a potential stimulus and each, at least in principle, is treated on its merits depending on the circumstances and on the individual’s own history. Of course there are general patterns and there is some consistency, for if there were not then the science of biology as a whole would be impossible. But we can never hope to predict precisely the effects of any one dietary component on any one individual or on the population as a whole. Most of all, we can never hope to control the bodies of human beings or other animals to the nth degree as sometimes seems to be the ambition and the promise. Of course, physicians and farmers who deal with real creatures have always known this. Science can take us so far but for the rest we need experience and intuition.
In conclusion
In short, taken altogether, modern nutritional theory tells us that we should and must continue to rely on carbohydrate as our chief source of energy, which in the main means starch; that healthy adults at least need only modest amounts of protein, which again can come largely or indeed entirely from plants; but that small amounts of meat, dairy, and eggs do have their place, if not necessarily as the chief providers of protein then at least as a valuable guarantor of protein quality and a prime source of some essential minerals and micronutrients; that it is best not to derive more than 30% of our calories from fat; and that the fat we eat should in general be polyunsaturated (or monounsaturated olive oil) as provided by oilseeds and fish – but mainly by oilseeds since fish are being overfished; and that we need a wide spectrum of micronutrients including cryptonutrients that are too numerous and too recondite in their effects to be fully analysable; and that to ensure we cover all bases we should consume a very wide range of foods, with special emphasis on fermented foods.
In other words we need “plenty of plants, not much meat, and maximum variety” – which is what nature and provides and agroecology strives to provide and traditional cooking veers towards. In other words there is a near-perfect correspondence between agroecology, modern nutritional science, and the crafts of traditional cookery. In other words all most of us need to do is to re-learn how to cook – and we need to organize our affairs and devise an economy which makes all this possible. Serendipity indeed.
The above is largely based on chapter 7 of my most recent book, The Great Re-Think, published by Pari in 2021.
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