As books that give answers go, there’s one classic that often gets overlooked – the dictionary. So next time you’re wondering whether a £10 tub of the latest miracle food can really stave off cancer, diabetes and heart disease, and get rid of a podgy belly in time for summer, run your finger down to the word “miracle” where you will find this definition: “an extraordinary and wondrous event” – so far so good – “that cannot be explained by natural or scientific laws”.
“Whether it’s coconut oil, chia seeds or apple cider vinegar,” says Duane Mellor, an assistant professor in dietetics at the University of Nottingham and a spokesperson for the British Dietetic Association, “there is no scientific evidence to suggest that if you top up your diet with any ‘miracle’ or special food that you’ll get any of the promised effects. The idea is almost entirely a marketing vehicle, but when people read claims online, they start to think differently and can start believing it.” One of the reasons people might believe the hype is because as with any good miracle – or magic trick – the success lies in smoke and mirrors. With miracle foods, while the magical health food salesman is conjuring a few extra coins out of our pockets, we’re left bamboozled by scientific terminology.
“Many products tend to be accompanied by all sorts of horrendous scientific jargon, like ‘maintains cognitive function’,” says Mellor, “which are watery, scientific-style claims that people tend to read as being something meaningful to human health. Then there’s antioxidants and free radicals, which are some of the most feared and misunderstood words used.”
Free radicals are unstable elements that come spinning off any oxygen-using chemical reaction in the body. They are unstable because they are missing an electron and, in a bid to restabilise themselves, they steal an electron from elsewhere. This could be from the fats in cell membranes or from your DNA. The damage they do when bullying other elements into handing over an electron is called oxidative stress, and this can be associated with heart disease, cancer and diabetes.
Free radicals, however, are also involved in beneficial processes. They help to destroy invading bacteria and play a part in cell communication. To limit their role to only those things that benefit us, our bodies make things called antioxidants that, much like people standing outside nightclubs handing out hugs and hot chocolate to pacify drunken revellers, provide free radicals with the electrons they need so they don’t cause damage elsewhere.
“But if you look at the antioxidants circulating in our bodies,” says Mellor, “by far the most common are the ones we make ourselves – glutathione and uric acid – followed by vitamins A, C and E, which we get from normal food anyway. Many of the antioxidants in things like chia seeds are there to stop the plant oils going rancid, or to protect them from sunlight damage, and may not be that available to our bodies anyway. So although the EFSA [European Food Safety Authority] allows manufacturers to claim that their products are rich in antioxidants – because they are – manufacturers are not allowed to claim any health benefits. If you look carefully, it’s sort of legalese what they end up claiming.”
Even when used as supplements, antioxidants don’t seem to provide any benefit. A large study published in the New England Journal of Medicine that followed nearly 10,000 people over an average of four-and-a-half years showed no benefit from vitamin E supplements in the prevention of heart disease. Studies for other antioxidant supplements have been equally discouraging.
Part of this confusion is because diet is complex. It’s tough to tease apart the contribution of individual components because the nutrients in many foods become available to us only when eaten as part of a wider diet: studies have shown that only when we cook carrots can their beta-carotene become more available and; the lycopene in tomatoes is most readily available when they are eaten with oil.
But what about all the other vague claims about foods that can help you lose weight, or support a healthy immune function, or lead to a healthy heart? They all sound good and sort of make sense, don’t they? According to Ali Khavandi, a cardiologist at the Royal United Hospital in Bath, these claims are vague for a reason – they are based on experiments carried out on animals or on human cells in a lab. They have not been shown to have any effect on people, and until such effectiveness is shown, he says, we should stay open-minded but cautious about exaggerated claims.
“As doctors I think we’ve taken our eyes off the prize,” he says of the importance of a healthy diet in avoiding the major chronic diseases such as heart disease and diabetes. “For the past few years, at least for heart doctors, I think we’ve been more interested in the sexier side of preventing disease – new drugs, stents, and operation techniques – and we’ve left the diet arena a little unmanned. It’s now been populated by unqualified people and celebrity health gurus spreading misinformation. As doctors I think we have an obligation to reassert an authoritative voice when it comes to healthy eating.”
Yanking the spotlight back from celebrities and fad food products might be a difficult task. “The problem,” says Khavandi, “is that the message we try to get across – which is based on proper, robust evidence that has been shown time and time again – is not very interesting to people. They have heard it all before.”
The messages he is talking about include the fact that fruit and vegetables are good for you. As are wholegrain cereals and nuts. For fats, which you need, choose unsaturated fats such as olive oil and those directly taken from marine sources such as oily fish. Neutral foods, he says, are saturated fats like butter or coconut oil and unprocessed red meats – eat these in moderation and they’re unlikely to do any harm. Stay away from excess white-flour products, processed meats, and trans fats such as vegetable oils and palm oils found in fast foods.
Simple enough advice on the face of it, but with sensationalised articles emerging daily about the benefits or dangers of specific foods, people get confused and lose sight of the simple messages. A complication nowhere more true than with cancer.
“There is certainly no such thing as an anti-cancer diet,” says Justin Stebbing, a consultant oncologist and professor of cancer medicine and oncology at Imperial College London. “But I have patients asking me things about these foods all the time.” He puts a finger on why cancer-busting food is such an appealing concept. “As a patient, disease makes you lose control. People immediately want to regain that control and a very easy way for them to do that is by diet, and they can get all sorts of things off the internet. We should understand that the internet is a double-edged sword and if we’re looking for information we should go to reputable sites.”
Such sites, says Stebbing, are NHS Choices, Cancer Research UK, Diabetes UK and the British Heart Foundation, which all give clear, evidence-based dietary recommendations. Duane Mellor has another simple rule of thumb for distinguishing cherrypicked claims from bona fide scientific evidence. “The EFSA is very clear – and very strict – about what health messages it allows companies to use in the marketing,” he says.
“If you see a claim on a blog, and if it’s persuasive and looks good, ask yourself why has the company not used it in their marketing? If the product really did prevent cancer or heart disease, do you not think it’d be plastered all over the packaging?”
No comments:
Post a Comment