Fergus was a farmer living near Cork in southern Ireland. He had retired late at the age of seventy and now had no more responsibilities. Being fit and healthy, he was looking forward to relaxing in his idyllic surroundings with Mary, his wife of forty-eight years. One day she noticed a lump on her breast and was diagnosed with metastatic cancer. Six months later she died. He became a bit of a recluse, kept close to his cottage, rarely went to the local town and didn’t mix with his neighbours. One sunny day three years later the local GP, with rare time on his hands, decided to visit him. Fergus had been on the practice list for years but had only ever visited in order to support his wife; he had never made a personal appearance or, apparently, needed to see a doctor.
The GP had remembered a very healthy man for his age, who was slim, didn’t smoke and was physically active. He was shocked at the change in him. His skin was sallow and grey, he had lost some teeth and he looked fragile. ‘I think you need to come in to the surgery for a check-up.’
Fergus now had high cholesterol, mild diabetes, high blood pressure and arthritis of the hip that gave him a limp. Also, his memory seemed to be fading.
The GP puzzled over the reasons, and asked the two most common questions doctors ask in Ireland: ‘Are you depressed?’ and ‘Are you drinking?’
‘Well Doctor, you are right,’ Fergus replied. ‘I was real upset and tearful and took to overdoing the drink. But only for the first six months. Then I pulled myself together, gave up the booze except for the occasional Guinness, and I’m OK now.’
The mystery of his recent deterioration was finally unearthed by the practice nurse. His wife had previously done all the cooking; he couldn’t boil an egg and was too proud to ask for help. He had lived on tea and cheese sandwiches for the last three years. Fergus moved to a local nursing home a few months later. Although his diabetes was treated, he died in his sleep of a heart attack within six months.
A microbe collaborator of mine, Paul O’Toole, who was working in Cork at the time, told me this story as typical of many in the area, in which a dramatic change in nutrition in an elderly person had preceded health problems. Paul’s research group is looking into the effects of the microbiome in the elderly, and particularly the effects of diet. In an important study they surveyed 178 Irish residents from local nursing homes aged 70 to 102, half of whom came temporarily for day care and the rest who lived there permanently.1
They found that within six months all the permanent residents on the same dull, institutional diet developed a similar microbiome. Unfortunately, it wasn’t a healthy mix and was lacking in diversity and many of the healthy microbes. It also indicated greater levels of inflammation. Those elderly part-time residents who sometimes cooked for themselves and ate non-institutional meals had healthier microbiomes than those with the communally prepared food. There was some variation, but within a year of entering the long-stay nursing home all the residents had very similar and unhealthy microbiomes.
In elderly people there are many complex reasons why the body deteriorates. These include loss of muscle through lack of physical exercise, depression, social circumstances and loss of cognitive function. The loss of teeth, changes in saliva, and the increasing use of antibiotics and other drugs can also affect the microbiome. With age, we see increases in the number and dysfunction of the protective Treg cells, which as we know interact with our microbes and at this point in life can over-suppress the immune system. Even when all these other factors were accounted for, diet and nutrition remained the dominant factor in determining the microbiome and its relation to health in the elderly. The residents with the least diverse gut microbiomes were far more likely to be frail and suffer from illnesses – and whatever the cause, were more likely to die within a year.
When Claire Steves in my lab looked at 400 of our older UK twins living independently who were generally frail, she found that they had a less diverse microbiome than average and lower numbers of microbes associated with suppressing inflammation and gut leakiness, such as F. prausnitzii. They also had fewer beneficial lactobacilli. This was the same result as an earlier, smaller, study of frailer old people had produced, so unlikely to be just down to chance.2 We think it likely that the changes in diet led first to the changes in microbes and then the frailty, rather than the other way around.
The exact deficiency in the residential diet that had had such a dramatic effect was unclear. Alcohol drinking at the residence is not encouraged. Although drinking the barley-rich Guinness was once thought to be healthy, the company has not used the health claim for many years, so Guinness deficiency is unlikely to be the major factor. Apart from the obvious monotony of the diet, the main culprit appears to be a lack of regular fresh fruit and vegetables – carbohydrates, in other words.
Carbohydrates come from plants and fruit, and in many different forms; they vary in how easy it is to extract energy from them. Confusingly, they are also called ‘saccharides’ after the Greek word for sugar. When the molecules are small, that is, one or two joined together, they are known as monosaccharides and disaccharides, respectively; they are what we commonly call sugars and are used in processed foods. When longer they are called polysaccharides and are used either for energy storage or for maintaining the structure of the plant, its fibre.
Most of the edible carbs in our diets are called starches, which are the main energy store for plants and the main ingredient of potatoes, bread and rice. They consist of groups of glucose molecules in long, tightly bound chains. Some forms are easy for us to break down and others are more resistant. As we saw earlier, humans have just thirty enzymes to break down all the complex carbohydrates they ingest, but luckily our gut microbes have over six thousand at their disposal to do the job properly. Without our microbes waiting to get to work on them, most of our carbohydrates would be simply a good workout for our jaws.
Raw-foodies and the toxic tomato
Paleo food enthusiasts claim – falsely, as we discussed previously – that we haven’t evolved sufficiently to eat the new foods produced in the last ten thousand years, and raw-food advocates go further to apply a similar logic to avoiding cooked foods, which we have eaten for up to a million years. The raw-food movement promotes a form of veganism that claims that cooking foods removes much of their natural nutritional value and destroys useful enzymes. The movement comes in many forms and in different degrees of strictness and orthodoxy, including fruitarians, juicearians and sproutarians.
Some of the more liberal of these groups allow vegetables to be slowly warmed up to 45 degrees C, which doesn’t destroy any of the nutrients or enzymes. This involves lightly cooking the food for long periods, and there is some scientific basis for the method. A few high-end restaurants have started to use these hypo-cuisson methods to cook meat, fish and vegetables for up to twenty-four hours. My experience of this recently in a Brussels Michelin starred (and inevitably pricey) restaurant was of amazing flavour and texture. I visited the kitchens of Comme Chez-Soi afterwards. Having no grills or ovens, it looked more like a space-age lab than a kitchen.
Anyway, most raw-foodies usually don’t eat meat and are more interested in the health benefits than the taste. According to them, the ‘valuable and intact’ enzymes are precious to us. This is despite the annoying fact that our digestive processes effectively and promptly deactivate them. Clearly, we have continued to evolve during the last million years and those diehards who kept on eating raw food died out long ago – and for good reason – it’s hard to extract sufficient calories and nutrients without cooking it at least a little. With the development of cooking we gradually lost over a third of our intestines, along with the ability to exist on raw food. In the modern world this could be a good way to slim down, not because of the benefits bestowed by the magic enzyme ingredients but just because we can’t efficiently break down the complex carbohydrates into energy.
Restrictive raw-food or paleo diets clearly have some advantages, and reducing refined carbs and avoiding processed foods is a big plus. However, reducing choice and diversity by excluding whole ranges of foods is a big mistake. For example, as mentioned already, paleo diets point the finger at poor old tomatoes as they come from a large family of mainly toxic nightshade plants to which ‘we haven’t had time to adapt’. This is daft. Saying the tomato or its family is the cause of auto-immune disease is also very misguided, and using pseudo-science to focus on side effects of one or two of its hundreds of chemicals is worse. No studies have convincingly implicated tomatoes as the cause of disease, and they are an essential part of the Mediterranean diet, the only one proved to reduce heart disease. Moreover, other more rigorous studies show that one of its many chemicals, lycopene, may help to prevent cancer, which is certainly not a good reason to eliminate it.3
While a lack of diversity and particularly of fresh produce and their nutrients is bad for us, at the other extreme the Web is bursting with colourful stories of people who exist on nothing but raw fruit and nuts – the fruitarians. They claim miraculous powers and energy, yet only very few can sustain this without spending many hours in the kitchen chopping and juicing, or on the toilet.
One exception is Freelee the Banana Girl, a former bulimic from Adelaide who for the last decade has been eating 90 per cent of her diet as fruit, with the odd cooked vegetable thrown in. She is now an ultra-toned fifty kilos, and according to her website lives in Queensland in a skimpy bikini surrounded by bananas and photographers. She has a popular video showing her eating fifty-one bananas in one day, washed down with coconut milk, which in theory gives her an intake of over 4,000 calories.
Yet despite not limiting her intake of calories she stays slim. She does admit to usually only eating twenty-odd bananas a day, but will have more or other fruits if she feels peckish. She always stays on raw food till 4 p.m., then may have some lightly cooked vegetables for dinner. She has concocted a range of diets and cookbooks and the thirty-bananas-a-day diet is widely promoted, with reports of both spectacular successes and failures.
Before you sign up for her health plan you should know that she also believes that losing your periods from dieting for nine months is good for you, and that fruit not chemotherapy is the treatment for cancer.4 Other fruitarian advocates were the late Steve Jobs, whose company was clearly influenced by his diet, Mahatma Gandhi and reputedly Leonardo da Vinci, though mangoes and bananas may have been hard to get in Renaissance Florence. There are even several ultra-marathon runners who eat only fruit and claim it gives them special powers. But for many, this lifestyle is a modern form of eating disorder.
Juicing and detox miracles
‘I look like I swallowed a sheep.’ It was 2007, and a Sydney stock market trader named Joe Cross looked in the mirror and realised he was very fat. Without further delay he started a juice fast of sixty days. His aim was to lose weight permanently and get rid of an auto-immune disease which made him dependent on medication. ‘I wanted to retake control of my life.’ As a kid he had a big appetite and loved junk foods and sugary drinks, but was sporty and stayed slim. These habits continued into adulthood, and once for a bet he ate eleven Big Macs at a sitting. He regularly had four or five Cokes a day, as well as several beers to chase down his Chinese meal during working lunches. He had an addictive personality and had struggled with alcohol, and like his father he had been a keen gambler.
Over the years he had focused on being wealthy and successful and his weight progressively increased. He had tried all kinds of short diets and fixes before. He was even a fruitarian for a month, before relapsing into his old habits. His 2010 documentary film entitled Fat, Sick, and Nearly Dead was an apt description of his situation. At the age of forty, Joe weighed over 140 kg (308 lb) and was dealing with the rare auto-immune illness, urticarial vasculitis. He was at high risk of heart attacks and diabetes. According to friends, behind the jokey, rich, beer-drinking Australian this was someone on the brink of suicide.
The urticaria had developed ten years earlier out of the blue after a game of golf in California. It is a strange disease in which the small blood vessels overreact to all sorts of stimuli and produce histamine. Even in a large teaching hospital I have seen only a few cases, and it can also cause arthritis. It behaves partly like an allergy and partly like an auto-immune disease. When triggered by changes in heat, touch or even pollution, the skin comes out in big red blotches like nettle stings or horsefly bites.
Sometimes even a handshake could set him off, and the skin would immediately become red and blotchy. The body then reacts by sending fluid through the leaky blood vessels and the skin puffs up as in a major allergic reaction. There is no cure for the disease, although steroids and other immune-suppressants can lessen the symptoms. He was taking cortisone (steroids), which like for most auto-immune conditions helped a lot at first, but longer term it increased his appetite and exacerbated his weight problem (and it has many other side effects).
For sixty days Joe followed his chosen plants-only diet: he juiced for breakfast, lunch and dinner. He often had a fruit mix in the mornings, but his staple, which he called his ‘mean green’ mix, consisted of six kale leaves, one cucumber, four stalks of celery, two green apples, half a lemon and a slice of ginger. He carried his own juicer and generator with him wherever he went. He was not permitted alcohol, tea or coffee and had no other food or drink. The first three days, he said, were very tough, then he settled into it.
He deliberately did all this while travelling across America to see how people would react. He wanted to test his will against the ultimate junk-food country, he said, and be faced with continual temptation.
By the end of Joe Cross’s juicing journey he had lost 37 kg (80 pounds) – that’s around half a kilo a day – and his cholesterol levels had dropped 50 per cent. He said he felt great, pumped full of energy. This healthy glow continued when he started eating solid fruit and vegetables. He was able to gradually tail off, and under supervision his cortisone was stopped and his urticaria didn’t reappear. He also managed to convert to his regime an even more obese truck driver – bizarrely, with the identical rare urticarial condition – whom he met in Arizona and who successfully followed his methods.
Joe Cross and his story have proved inspirational. Many people have tried his method, usually on two- to ten-day juicing fasts, and with differing levels of success. But he had certain little advantages: he was rich and single, could take sixty days off work, and he had a doctor and nutritionist to guide him with his health and his food. He also had a dedicated film crew in tow, although that wasn’t always a help, he said, because he had to sit in the car while they were tucking into a McDonald’s.
Importantly, he had the motivation of his illness and also the film about his personal trial. However, the real test was not whether he could complete the diet, but whether he could maintain his new healthy weight. Five years later things were still looking good. On a super-healthy vegetable diet with intermittent juicing he has managed to keep his weight off and has even lost some more.
Juicing and detoxing have taken off as methods to lose weight and ‘reboot’. There are few or no scientific studies or trials of juicing, and most of the information comes from individual stories and promotional sites on the Web. It is certainly popular, and in many countries sales of expensive juicers and ready-made mixes have shot up. Clearly, large quantities of fresh fruit and vegetables are an ideal source of nutrients, most of which we can’t get from meat and refined carbs. The concept espoused on many nutritional websites is that consuming juice rather than whole foods offers a number of advantages that put your digestive system in a relaxed ‘holiday’ mode. Is this true?
The nutrients are absorbed, we are told, without any effort and this process also gets rid of toxins in some way. These ‘toxins’ are never well defined, but some sites call them acids, dead cells or products of decay. The toxic products apparently accumulate in your cells, to dangerous levels. The ‘mass of dead cells, toxins and acid then spills into your blood’, causing inflammation. This leads to chronic sickness, a weakened immune system and an increase in most known diseases. Help is at hand, though. Juicing with the super-concentrated doses of super-nutrients combined with fasting eliminates your toxins, balances your blood pH and thereby purifies your body.
By now you will have realised that this kind of story which is repeated in many books and on websites is, sadly, complete mumbo-jumbo. The nutrients in fresh juices are of course good for you, but the pseudo-scientific claims widely made for detoxing the body by juice fasting are meaningless to any serious scientist or doctor. The ideas might have resonated in the Middle Ages when purges, leeches and blood-letting were all the rage, but our bodies (outside of sci-fi films) do not build up with excess toxins or spill over with acid or need a regular de-scaling.
Fasting to clean up your microbiome
Many people lose some weight through juicing but this could be another form of fasting. Although fasting has no common definition, it generally means eating or drinking between zero to 30 per cent of normal daily intakes. In 2013 a new fasting-based diet book was released which broke all sales records in the UK. The Fast Diet was championed by British TV presenter Michael Mosley.5 Michael was making a BBC documentary on diets and fasting and tried out different regimes on himself. One of these involved several days of continuous deprivation on just a few hundred calories a day. This pure form of permanent fasting called Caloric Restriction (CR), is only for the ultra-determined. Michael managed it and lost weight, but felt this was too tough physically and psychologically for most people with normal lives.
After discussions with other scientists he tried out a more practical method which cut daily calories down to less than one-third of normal intake (500 calories for women, and 600 calories for men) for only two days a week, with five days normal eating. On the fasting days this could mean having an egg and fruit for breakfast, a handful of nuts and carrots for lunch and fish and vegetables for dinner, with plenty of herbal teas. Michael, although never what we would call fat, found he lost a stone (7 kg) in weight fairly easily over the five weeks and could eat and drink what he liked on non-fasting days. His body fat percentage surprisingly dropped even more rapidly from 27 to 20 per cent.
I tried the diet myself for a couple of weeks, just to assess its practicality. On my busiest days at the hospital, when I had no time to think about meals I found it easy knowing that I could, in theory, eat what I liked the following day. Like others, the next day after fasting I strangely had no extra urge to devour a full English breakfast and felt virtuous and somehow healthier. Michael and his team concluded that the most plausible reason for the extra weight loss and metabolic improvements was the body responding to the short famine by releasing increased amounts of a hormone IGF-1. This hormone is believed to have anti-ageing properties in some animals and generally reduces cellular stress and inflammation. But most of the good evidence of IGF-1’s benefits comes from the extra longevity of worms and flies.6 Results in rodents are less clear and the animals with high levels have early stunted development as well as a lack of energy and sexual interest which only seems worthwhile if you are trying to live for ever.
The results of intermittent fasting appear to be more significant than simply the effect of a reduction in calories. There are no recent long-term studies in humans, but in Spain in 1956 – under General Franco’s regime and before ethics committees existed – a Spanish residential home for the elderly was used for an unrepeatable and little-known study. The home was run by a tough group of nurses from St Joseph’s in Madrid. The 120 long-suffering residents (who were probably not chubby to begin with) were divided into two groups. One group had all their meals unequally distributed so the calories varied on alternate days: one day they got only 900 calories (a litre of milk and fruits), and 2,300 calories the next. The other group got the same average of 1,600 calories every day, which was considered normal for their size and age. After three years of this regime the alternating group had half the rate of death (6 vs. 13) and half the number of days spent in hospital for flu, infections and other problems.7
Humans have, of course, been intermittently fasting for thousands of years – in the name of religion. In fact every major religious group, including Christians, Muslims, Jews, Hindus and Buddhists and many more, have fasting as a part of their culture and discipline. It was clearly hard to start a new religion without some change in diet and a bit of healthy fasting. Most of the religious dietary practices adopted were linked to a potential health benefit, so fasting must have been given the same status.8
Many animals fast naturally in the wild. Hibernating animals such as squirrels have very different seasonal gut microbes when you examine their droppings before or after hibernation, and the change seems to be beneficial. Their levels of diversity are greatest after two weeks of re-feeding in the spring when their healthy butyrate levels go up. Hibernating microbes living off scraps of the gut lining proliferate, and ones that depend on food disappear.9 Burmese pythons grow up to 18 feet long and have a more varied diet than mice and pigs but never know when the next meal will come along. This means they have long fasting periods, which can last over a month, when their stomach shrinks down. Intrepid researchers examined python droppings and found similar microbial changes to the fasting squirrel in the microbe community and then large shifts one or two days after a tasty meal.10 It appears that all animals have this natural relationship with fasting and their microbes.
Experiments on lab mice have shown that if you disrupt their normal nocturnal pattern of eating and make them eat more like humans their gut microbes become less healthy and they lose the natural daily cyclical pattern of change in their microbes. If you then compress all their eating into short 6–8 hour periods with 18-hour gaps between meals, they become even healthier, leaner and resistant even to high-fat diets.11 The major microbe that loves fasting is called Akkermansia and it snacks off our gut lining and cleans it up, strangely improving the diversity of the other species. However, if we go for too long without food the microbe can damage the gut lining and cause problems. In our pilot studies for the American and British gut projects the greatest beneficial microbial changes were seen in the fasting groups with major increases in diversity.
So if fasting short term is good for our microbes, should we be altering our meal times?
A healthy start to the day – or is it?
A popular nutritional assumption has long been that we should eat at regular intervals to avoid metabolic disturbances and compensatory overeating later. Another is that you should space meals out evenly to aid digestion. The idea of deliberately fasting may seem odd to many people, yet most of us fast regularly for 10 to 12 hours overnight without any problems. So why can’t we also fast in the day for more than 4 to 6 hours – without complaining of a ‘hypo’ and reaching for a chocolate biscuit? The dogma in the Anglo-Saxon world about always having to have breakfast to maintain metabolic health and reduce overeating is even stronger. Over a third of the populations of Spain, France and Italy skip breakfast completely although a few people would have a quick espresso at the bus stop. They seem to be quite healthy and may not have much to eat most days until 2 p.m.
The fact is that we have been misled by indoctrination from breakfast cereal companies, compounded by a whole series of poor-quality cross-sectional studies. These reported an association between people who regularly skipped breakfast with obesity, poor glucose control and overeating later in the day.12 The problem with these studies (as we have seen before) is that they are small-scale, cross-sectional associations focusing on the habits of obese patients who were already metabolically abnormal. Two recent studies have accounted for body weight while performing actual trials of a few weeks of skipping breakfast. Both showed no increase in weight or total calories in the breakfast skippers. In fact, there was a slight reduction in total intakes with no change in metabolic rate whether you were fat or lean.13 Evidence that most children suffer from lack of breakfast is equally weak and no proper trials have been done.14 So compulsory breakfast is another diet myth that should be buried.15
Some people still feel they really need their breakfast: this is partly cultural and partly genetic. Our twin studies have shown a clear gene influence on whether you are a morning person or an evening person, and these differences in circadian rhythms undoubtedly affect the times when you prefer to eat.16 We should let our bodies not dogma or guidelines determine our choice of breakfast and mealtimes.
The three-meals-a-day routine is actually a surprisingly modern invention – only coming to the west in the Victorian era. We don’t know for sure but suspect our Palaeolithic ancestors only had one main meal a day. The Greeks, Persians, Romans, and early Jews all ate one big meal per day, usually in the evening to celebrate the day’s work. It wasn’t until the sixteenth century in England that two regular meals became more common, but only for the well off. A contemporary proverb proclaimed this was the healthy new recipe for long life: ‘To rise at six, dine at ten, sup at six and go to bed at ten, makes a man live ten times ten.’ The habit of only two meals a day among even the rich upper classes is made clear by the Countess of Landsfeld, who in 1858 described her companions eating habits: ‘after this meal comes the long fast from nine in the morning till five or six in the afternoon, when dinner is served.’17
The evidence clearly shows that increasing our fasting periods, whether by cutting out or compressing some meals, could actually be better for us – even if we consumed the same number of calories daily. One shorter version of the Spanish nursing home study gave volunteers the same food content and calories either as one giant single meal or as three small divided meals. The study lasted for eight weeks and then after a break the volunteers swapped over to the other regime. There were no significant differences on heart rate, body temperature, or most blood tests. However, the single meal produced more feelings of hunger, slight increases in blood lipids, but significant reductions in body fat and in the stress hormone cortisol.18 So although you may feel hungrier by skipping two meals, there is no evidence it will do you any harm, and it may have even have metabolic benefits for you and your microbes. Their powerful circadian rhythms are important for our immune system and health, and are helped by fasting.
Superfoods and super microbes
‘Superfoods’ form the basis of a massive growth industry. People are willing to pay big money for what they perceive to be the most nutritious ingredients, or for an exotic nut or vegetable that their friends have never heard of, especially if it is reported to have magic healing powers. Of the few superfood studies that make it to bona fide scientific publication, most of the ‘amazing results’ are shown only in test tubes or, if rarely, in rats fed huge amounts of the pure compound. Only a tiny fraction have ever been studied properly in humans, at the correct doses or with normal food – and then only very short term. Commonly cited examples of superfoods are pomegranates, blueberries and the much hyped acai berries with their potential antioxidant properties, and even boring beetroot which apparently alters nitric oxide levels.
Other trendy superfoods are more exotic. They include freshwater Asian marine algae like Chlorella, which is very green and apparently has immune-disease-, diabetes- and cancer-fighting properties and costs ‘only £90’ for enough to last a month. Blue-green algae, like Spirulina (which I was given in the form of a slimy soup recently), is another ‘immune-busting’ superfood with plenty of protein and vitamins. Unfortunately it costs, per gram, thirty times more than meat. Spirulina is formed by groups of microbes that stick together on lakes and are actually a type of ancient bacteria – cyanobacteria. These microbes were responsible for providing the earth’s atmosphere and evolved into chloroplasts in leaves, so we could consider them ancient probiotics. Some of these microbial species that we thought only existed in water we actually found living in the guts of our twins19 This reminds us how much there is still to learn of the microbes we share our bodies with.
Like other bacteria that can produce vitamins, Spirulina produces vitamin K and a form of B12 that has been heavily touted by vegan websites as an alternative to meat. However, there is no evidence that it has the same key properties or benefits as real B12.20 As with seaweed, unless you have the right gut microbes and their 30,000 special enzymes, you will not be able to extract the nutrients from the more exotic marine superfoods.
Superfoods may seem a fun concept, but they are also a marketing con, as virtually every fresh fruit and vegetable is a superfood. They are all packed with hundreds of different chemical compounds that people can dream up long lists of attributes about. Some consider yoghurt, quinoa, eggs and most nuts to be superfoods, and from the earlier chapters of this book we could add traditional cheeses, olive oil and garlic – the potential list is endless. One book on the market lists the latest top 101 superfoods.
What is becoming clear is that many foods don’t work nutritionally as well in isolation as they do when combined together. Spinach and carrots are good examples, as both contain the nutrient carotene that is better absorbed in the presence of the fat in olive oil dressing.21 This is yet another reason, if you still needed any, to avoid reductionism in our food choices. Sporadically feeding yourself large amounts of a few selected ‘superfoods’ is likely to be much less effective than regularly eating a wide variety and diversity of plants and vegetables.
Juicing long term with too much fruit can be dangerous, as it produces large amounts of fructose and calories without enough accompanying fibre, which among other benefits dampens down the speed of the sugar absorption. Dentists have noticed recently increases in new cavities in healthy, over-keen twenty-something juicers. Instead, adding a regular multi-vegetable juice to your diet appears much healthier. It can be prepared cold or briefly heated as soup. Studies have shown that people are more willing to eat a wide variety of vegetables as soup than if served naked on a plate. If the soup is thick and the vegetables only lightly cooked, it also slows down digestion and can send signals of fullness to the brain and lower intestines. The other advantage is that nutrients are not lost in the water, and most people in normal health can eat many more plants as a juice or soup than raw or by traditional cooking. Using juicing machines that preserve the pulp and fibre and so many of the nutrients seems sensible if it doesn’t become an obsession.
Be kind to spinach haters
The average Western diet is deficient in fibre, and in carbohydrates from vegetable and fruit. As a consequence it is likely that the average healthy person is actually abnormal in terms of their gut microbes, as the gut community are being starved of accessible carbohydrates.22 It doesn’t help that many people have strange aversions to many vegetables – we discussed a few cases earlier. One study of babies aged eight to eighteen months found real aversions to touching or eating green plants, similar to the natural aversion to snakes or insects.23
This green aversion manifested, for instance, as a hatred for school spinach, may have an evolutionary basis as a means of stopping children randomly picking up some toxic green plant and eating it. Genes, as always, play a role, and as all parents know, some kids have stronger aversions or food avoidance instincts than others, particularly for new foods. This so-called neophobia often continues into adulthood as fussy eating. Such individuals are less likely than others to try any new food or taste, and end up on more restricted low-nutritional diets. We found in our adult twins a very strong heritable and persistent fussy-eating component.24 Changing the particular food’s physical form by using tricks like juicing may be one way of reducing these aversions; and introducing bright non-green colours could help.
In the modern world we should treat as a superfood any plant or vegetable that assists our microbes in their work. But rather than focusing on single ingredients and spending our twilight years eating Spirulina soup three times a day, we should be thinking more of superfood communities. The wider the range, the better. Whether you achieve this via soups, juices or raw or cooked foods is probably not so crucial. As well as what we eat, the timing and space between meals may be more important for us and our microbes. Gut bacteria along with all animals need to have regular patterns of work and long rest periods to function optimally. As well as the nutrients and polyphenols, many real foods contain fibre that makes them tough to digest and give our microbes a good workout, and this we were told is good for us.