Why vitamins are hard to swallow

Many of us take vitamins as a quick fix for good health. But a range of studies show that some supplements are useless – and could actually harm us. So should we stop popping pills? By Dan Roberts

(Alamy)

The recent country-wide demonstrations against homeopathy, in which sceptics staged mass "overdoses" of homeopathic remedies, illustrated the bitter divide between those who believe in this complementary medicine and critics who dismiss it as quackery. Homeopathic practitioners argue that their remedies are effective, despite overwhelming scientific evidence to the contrary. And sceptics, pointing to this evidence, retort that homeopathy is a waste of both private and public money and can be downright dangerous, if used to treat a life-threatening condition like cardiovascular disease.

At the same time, a similar debate has been simmering away about another branch of complementary medicine: the multibillion-pound nutritional supplement industry involving major high street names. Concerns about the safety and efficacy of these supplements are not new. Back in April 2008, the Cochrane Collaboration – a highly respected international organisation that provides systematic, unbiased reviews of medical literature – looked at 67 randomised trials involving around 232,000 participants. The review found that, far from boosting health and preventing disease, as their manufacturers claimed, there was no evidence that antioxidant supplements prevented a range of diseases, including gastrointestinal, cardiovascular and neurological conditions. Worse still, the researchers found that taking the antioxidants vitamin A, beta-carotene and vitamin E may increase your risk of mortality.

Goran Bjelakovic, a medical researcher at Copenhagen University and lead author of the Cochrane review, warns that antioxidants should be treated as medicinal products. "For many years, scientists have been concerned about the possible harm caused by antioxidants," he says. "There are still gaps in our knowledge of the mechanisms of bioavailability, biotransformation and action of antioxidant supplements. Data on adverse events of antioxidant supplements are still limited and under-reported. But consumers presume these supplements are safe and use them without their doctors' supervision."

Last November, a study by researchers from Haukeland University Hospital in Bergen, Norway, found that patients with heart disease had an increased risk of cancer and death from any cause if they had received treatment with folic acid and vitamin B12. The findings are especially revealing because foods are not fortified with folic acid in Norway (unlike in countries including the US, where flour and grain products contain added folic acid to reduce birth defects). The Norwegian team argues that more research is needed into this area, but the results do throw into question the wisdom of taking supplements without a clear understanding of their potential side effects.

Meanwhile, some experts argue that taking the type of "synthetic" supplements commonly sold on the high street is, at best, ineffective and, at worst, harmful to the body. "A number of studies have shown that taking supplements increases your risk of mortality," says Dr Rajendra Sharma, medical director of London's Diagnostic Clinic and a specialist in integrated medicine. "That was confusing to me as a physician, because there are hundreds of studies showing the benefits of antioxidants in reducing the risk of cardiovascular disease and cancer. So I decided to look into the evidence more closely and realised that the antioxidants carrying a health risk were pharmaceutical-grade, or 'isolate' supplements."

Dr Sharma argues that these supplements are manufactured by pharmaceutical companies and bear little resemblance to the natural vitamins and minerals found in fruit, vegetables and other foods. "So the Cochrane Review, which found that vitamin E may increase the risk of mortality, was not talking about vitamin E found in its natural state," he says. "The component in those supplements was alpha-tocopherol, which is just one part of eight different components found in naturally occurring vitamin E." These other components include flavonoids and carotenoids, found in carrots, sweet potatoes, spinach, kale and tomatoes. Without them, says Dr Sharma, the body cannot successfully absorb the isolate vitamin. "This creates a deficiency in vitamin E, an antioxidant that destroys the free-radical cells which cause cancer," he says. Dr Sharma is not against supplements per se; he just thinks we should take them with care and under medical guidance. He also recommends eschewing isolate supplements for a more natural alternative. "I strongly believe that people should only take natural 'food-state' vitamins and minerals – I think going out and buying vitamin C, in isolate form, from, say, a chemist, is actually dangerous."

This is a bold claim, which we will return to shortly. But proof of the supplements industry's fallibility came last year, when hundreds of products were quietly removed from the shelves of UK shops. This under-reported event resulted from a Food Supplements Directive brought into force by the European Commission in 2002, but which only took effect at the end of 2009 because of legal challenges from the health food industry. Nina Papadoulaki, EC spokesperson for health, explains the reasoning behind this mass product cull. "Vitamins and minerals are essential nutrients, but in some cases excessive intake can lead to adverse health effects," she says. "Therefore the Food Supplements Directive foresees the setting of maximum amounts of vitamins and minerals present in these supplements."

In addition to capping the dosage levels of supplements, the European Food Safety Authority drew up a "positive list" of vitamins and minerals deemed non-hazardous to health. Any nutrient not on the list is now banned from sale, including six minerals (tin, silicon, nickel, boron, cobalt, and vanadium) that had been used in food supplements on sale in the UK for many years.

This is worrying enough, but critics of pharmaceutical supplements want the EC to go further, banning the synthetically manufactured vitamins they regard as harmful. Among their number is Amanda Williams, managing director of Cytoplan, a UK distributor of the "food-state" supplements advocated by Dr Sharma. Why does she consider these to be superior? "Our philosophy is that the body is designed to utilise nutrients from food and not from chemicals," says Williams. "Food-state products are beneficially combined with a food base in which that nutrient would naturally be found. This means that the nutrient complex contains all the other food factors necessary for absorption and utilisation in the body. For example, with vitamin C, it is believed that the flavonoids which are always combined with it in nature are predominantly responsible for the absorption, retention and useful metabolism of the vitamin."

Williams adds that research shows when vitamin C is ingested as pure ascorbic acid – the chemically isolated form of the vitamin – it is rapidly excreted by the body, because it is perceived to be a toxic substance. She also argues that the average daily diet is woefully lacking in the most basic nutrients. "We are lucky to get half the nutrition our parents and grandparents did in the Fifties and Sixties," she says. "We eat far more processed food and Government data shows that young males, for example, only eat 1.3 portions of fruit and vegetables per day rather than the Government-recommended five a day."

According to Williams, we need supplements to bridge this "nutrition gap". Sara Stanner, from the British Nutrition Foundation, disagrees. "The reason nutritionists bang on about eating foods rather than supplements is that when you eat a food you consume a massive matrix of nutrients, some of which you can isolate and put into supplements and some you can't. The latter tend to be bioactive substances like phytonutrients, found in fruits, vegetables and grains."

This does seem to support the food-state argument, but Stanner says it's far from simple. "With milk, for example, you will absorb more vitamin A because it also contains fat. But that's not true of all foods. I'm also concerned that people might think by taking one of these supplements they don't need to worry about their diet, which is not the case."

Stanner also argues that taking any supplement might overload you with a particular nutrient. "If someone's taking a vitamin supplement and getting that vitamin from their diet, they could end up with a huge dose that's actually detrimental to health. Generally, we're best off eating a rich and varied diet – if we eat healthily, most of us are meeting our nutrient needs," she says.

The debate about whether we should take supplements and if we do, what kind, rumbles on. But it's clear that far from being a benign health booster, supplements need to be taken with extreme caution. Before you down a vitamin pill – especially a high-potency one – follow the tried-and-tested route of asking your GP if it's safe.

The Diagnostic Clinic: 020 7009 4650; Thediagnosticclinic.com

Cytoplan: 01684 310099; Cytoplan.co.uk

British Nutrition Foundation: 020 7404 6504; Nutrition.org.uk

Food Standards Authority: 020 7276 8829; Food.gov.uk

Safe supplements: The healthy options

* Vitamin D is a vital nutrient that helps regulate the amount of calcium and phosphate in the body, which in turn keeps bones and teeth healthy. It has also been linked with a stronger immune system and lower risks of illnesses like diabetes, heart and kidney disease, high blood pressure and cancer. It's found in oily fish, eggs and fortified foods such as margarine and breakfast cereals. But we get most of our vitamin D from sunlight on our skin, because it forms under the skin in reaction to this light. An increasing body of evidence shows that many Britons are deficient in vitamin D, especially during the winter.

* There is some debate about how beneficial vitamin D really is (a major study is currently under way in the US which should provide conclusive answers) and whether healthier people simply have high vitamin D because they exercise outdoors and lead a healthy lifestyle. But current Food Standards Agency advice is that older people, vegetarians, those of Asian origin or who are pregnant or breastfeeding should take 10 micrograms a day.

* Omega-3 fatty acids are thought to help protect against coronary heart disease. These are found in vegetable oils like linseed, flaxseed, walnut and rapeseed, but recent evidence suggests that they may not have the same benefits as those found in oily fish. The FSA recommends eating two portions of fish, one of which should be an oily fish such as sardines, mackerel or salmon, each week. If you're not a fan of fish, you may need a fish-oil supplement – the daily dosage depends on a number of factors, so always consult your GP first.