Chapter 34
Eat to Your Heart’s Content — Part 5
In the USA, antioxidant supplements account for a big chunk of the total intake, i.e. 54 per cent of vitamin C and 64 per cent of vitamin E. This is where the controversy starts. In laboratory experiments, antioxidants very effectively counteract the effects of free radicals. However, supplements do not have the same beneficial effects on health in humans unless taken as part of a good diet, such as the Mediterranean diet, which naturally contains many antioxidants. The question is, why is natural dietary source so much better than antioxidant supplements?
In one study, which included almost 40,000 healthy women 45 years of age and older, vitamin E supplements did not reduce the risk of heart attack, stroke, cancer, macular degeneration or cataracts. Another large study found no benefit for vitamin C, vitamin E or beta-carotene supplements on heart disease, stroke or diabetes. The Physicians’ Health Study II, which included more than 14,000 male doctors aged 50 or older, found that neither vitamin E nor vitamin C supplements reduced the risk of heart disease, stroke, diabetes, cancer or cataracts. In fact, vitamin E supplements were associated with an increased risk of stroke caused by bleeds in the brain in this study. In a study of more than 35,000 men aged 50 or older selenium and vitamin E supplements, taken alone or together, failed to prevent prostate cancer but rather increased the risk of cancer by 17 per cent.
Chapter 9: Eat to Your Heart’s Content
So, given that good diets contain antioxidants and prevent aforementioned diseases, why are antioxidant supplements not of the same benefit? Some explanations conclude that the beneficial health effects of a diet high in vegetables and fruits or other antioxidant-rich foods may actually be caused by other substances present in the same foods, other dietary factors or other lifestyle choices rather than antioxidants per se. Or it may be that the effects of large doses of antioxidants used in supplementation studies are different to the amounts of antioxidants consumed in foods. Differences in the chemical composition of antioxidants in foods versus those in supplements may also influence their effects. For example, eight chemical forms of vitamin E are present in foods. Vitamin E supplements, on the other hand, typically include only one of these forms. For some diseases, specific antioxidants might be more effective than the ones that have been tested. To prevent eye disease, antioxidants that are present in the eye, such as lutein, are possibly of benefit rather than a broad spectrum of antioxidants. Other posited reasons are that the relationship between free radicals and health is more complex than previously thought. Under some circumstances, free radicals may be beneficial rather than harmful and removing them may be undesirable. Antioxidant supplements may possibly not have been given for a long enough time to prevent chronic diseases. Another likely explanation is that the microbiome that we are about to discuss may be a main mediator in the difference between diet and supplements.
Chapter 9: Eat to Your Heart’s Content
In conclusion, diets high in antioxidants have multiple health benefits but there is insufficient evidence for antioxidant supplements to replace a healthy diet. It is best, where possible, to get antioxidants from foods rather than relying solely on supplements for health benefits. This is of course not something that the market wants to hear and I doubt that things will change, given the high use of antioxidants in US despite a dearth of affirmation. The microbiome, the bacteria in our gut, is one of the most exciting new discoveries in recent medical history. Our body houses trillions of bacteria, viruses and fungi, known as the microbiome. While some bacteria are associated with disease, others – the ‘good’ bacteria – are extremely important for our immune system, heart, weight and many other aspects of health. Most of the microbes that make up our microbiome are found in a ‘pocket’ in the large bowel. Microbes also live on the skin and in other organs such as the vagina – they are in fact everywhere in and on the body. The relationship between our microbiome and the food we eat is complex and important and may well provide valuable information for ageing.
Chapter 9: Eat to Your Heart’s Content
The story starts with the Hadza tribe in Tanzania, East Africa, a hunter-gatherer tribe, living beside Lake Eyasi, with only 1,000 of the tribe in existence today. Unlike Western civilisations, the Hadza have been eating the same diet for thousands of years. To study the gut microbiome, researchers went to live with the tribe to see how different the diet and gut microbiome of the researchers was compared with that of the tribe, postulating that the Hadza microbiome would reflect our gut some hundreds of years ago when diseases such as diabetes and heart disease were so much less common.
The Hadza live surrounded by mud, in grass huts. They hunt the same animals (antelope, wildebeests, baboons and porcupines) and eat the same plants that humans had done for 3 to 4 million years, such as honey, berries, baobao and tubers. They are nomadic and movements are dictated by availability of food. The food is raw and microbial-rich. For example, after a kill the tribe eat the stomach, which is rich in microbia, and squeeze faeces out of the colon, which is then lightly cooked. The Hadza have twice as many microbes as Westerners and do not suffer from Western diseases.
Chapter 9: Eat to Your Heart’s Content
Diversity in microbiome is a good thing. In order for our microbiome to thrive, our diet should be diverse and varied, in turn ensuring that our microbiome is diverse and varied. Researchers noted that it was possible to shift the diversity of gut microbiomes within 72 hours of changing a diet. Faeces are made up of microbes, alive and dead. While living with the Hadza, researchers took samples of their own faeces daily during the stay, which were itemised and examined when they were returned to the laboratory. This showed that, as the researchers ate the Hadza diet, the microbiome became more diverse even within a few days. Wait for it – some researchers also carried out ‘faecal transfers’ with the tribe, transferring, using a turkey baster, the tribe members’ faeces into the researcher’s rectum. This showed that diversity was even more evident after the faecal transfer.
This work has contributed to a wealth of studies that have expanded the possible causal role of the microbiome, not just in diseases such as diabetes, obesity and hypertension, but also in immunity and in brain health. Unfortunately, as we slip back into a Western diet, the microbiome changes back and becomes less diverse. It appears that some of our microbiome has become extinct because of restricted diversity in our diets and researchers postulate that the ‘missing microbes’ may well hold the answer to some of the diseases of ageing.
Chapter 9: Eat to Your Heart’s Content
When we eat, microbes are triggered to attach to the food; they start to break it down, take nutrients and energy from it and produce healthy chemicals, which in turn prevent infections, positively affect mood and suppress allergies. Because microbes are predominantly in the lower gut, fats and refined carbohydrates which are absorbed higher up in the gut don’t get as far as the microbes. Microbes love polyphenols, such as peanuts and seeds, which do reach them in the lower gut. To have a healthy gut, we need diverse microbes and therefore a diverse diet to keep the microbes ‘interested and stimulated’. Foods high in polyphenols are listed in the table opposite. Foods high in fibre are also particularly good for microbial diversity and for increasing the numbers of microbia. High-fibre foods include wholegrain cereals, wholewheat pasta, wholegrain bread, oats, barley and rye, berries, pears, melon, oranges, broccoli, carrots, sweetcorn, pulses, nuts, seeds and potatoes with skin. So there is plenty of choice – but that’s the point; we need all of these to keep our gut interested, stimulated and microbiome rich.
But what has any of this to do with ageing? Plenty, if not everything! The gut microbiome in long-lived persons and centenarians is very diverse. There are specific microbiota associated with longer life that we may be able to manipulate to test whether introduction of these particular microbes can be effective if introduced into the guts of people who do not have a rich and varied microbiome. This research is ongoing. But for you and me now, the message is that long-lived fit, healthy people have very diverse microbiota.