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How safe are your daily supplements?

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  • How safe are your daily supplements?

    Many of us pop vitamin pills in the belief that we are safeguarding our health. But, Chloe Rhodes discovers, some could be doing more harm than good

    Nutritional supplements have come a long way since the cod liver oil and fortified bread of the postwar years. More than 40 per cent of us now pop a pill once a day and the industry is booming. Britons spent about £360million on supplements last year and in America the annual spend was a massive $6billion.

    Last Friday, a report extolled the benefits of a cocktail of vitamins and minerals during pregnancy. We tend to see supplements as a harmless way of making sure we're fully stocked with all the nutrients we need; but a growing body of research is beginning to challenge this view.

    A different study published last week found that about a million women taking calcium supplements to combat osteoporosis were 50 per cent more likely to have a heart attack than those on placebos. Recent US research suggested that men taking multivitamins have a higher risk of advanced prostate cancer, while beta-carotene supplements were linked to an increase in the ominously non-specific "overall risk of dying".

    Patients prescribed supplements on medical grounds must balance these risks with the beneficial impact they might have, but we should all be aware of the risks. Catherine Collins, chief dietician at St George's hospital in London and spokeswoman for the British Dietetic Association, talked me through six of our favourite supplements.

    Vitamin A helps maintain healthy skin and mucus linings, strengthens immunity and prevents night blindness. (RDA 0.7 mg men, 0.6 mg women.)

    Multivitamins are the best-selling supplement and most are rich in Vitamin A. They are prescribed to children with measles and individuals who can't absorb fat as a result of cystic fibrosis, pancreatic disorders or after stomach surgery.

    Risks: "Excess vitamin A can cause problems," says Collins. "The regular use of supplements providing 1,500mcg or above of vitamin A is associated with an increased risk of fracture in elderly women. Too much vitamin A in early pregnancy can damage the foetus, so expectant mothers should avoid supplements.

    "Dietary sources are infinitely preferable - dairy products, fortified margarine, fish oils and liver, a single portion of which a week provides the recommended amount."

    Vitamin D protects against cancer, heart disease, tuberculosis and diabetes. It helps regulate the amount of calcium and phosphate in the body to keep bones and teeth healthy. Supplements are prescribed to anyone with a vitamin D deficiency, which is on the rise in Britain's ethnic minorities and causes rickets. (RDA 10 micrograms if you need a top up.)

    Risks: "This is the one supplement I do recommend (along with folic acid for mothers-to-be). Older people who are housebound and Asian women who cover up their skin when outside are unlikely to be able to get enough vitamin D from their diet and should take a supplement. Pregnant or breastfeeding women should also take 10 micrograms (0.01 mg) a day.

    "Vitamin D is created in the body when the skin is exposed to sunlight so I send my children out in the sun for 15 minutes before putting on sun screen. Food sources include oily fish and eggs."

    The Department of Health offers free drops containing vitamin D to children up to the age of four.

    Manganese is a trace element that helps make and activate an antioxidant enzyme in the body called superoxide dismutase. It is prescribed for diabetes, epilepsy, high cholesterol, Parkinson's disease, rheumatoid arthritis, and schizophrenia. (RDA from dietary sources.)

    Risks: "High levels can result in heavy metal poisoning," warns Collins. "I had a patient who was admitted to hospital unable to breathe. He had been paralysed in an accident some years previously and was fed with artificial feeds but was taking a manganese 'tonic'. He'd been ingesting several times the RDA each day and blood tests revealed he had heavy metal poisoning usually seen only in the steel industry. Anyone taking a combination of supplements should be wary of inadvertently exceeding the safe dose.

    "Tea is the biggest source for most people and nuts, bread, peas and runner beans are also rich in it."

    Magnesium helps turn food into energy and supports bone health. Supplements are prescribed for people with conditions that cause excessive loss of magnesium, such as severe diarrhoea and chronic or severe vomiting. (RDA 300mg men, 270mg women.)

    Risks: "Consuming high levels is easy if you combine supplements and too much can cause severe diarrhoea. I had a female patient with ME who had been admitted to hospital for investigation of such profuse diarrhoea that she was having blackouts due to dehydration," says Collins. "She was taking 10 magnesium supplements a day - far more than her body could absorb.

    "It's far better to get what you need from leafy vegetables, nuts, bread, fish, meat and dairy products."

    Beta-carotene is the plant version of vitamin A and performs the same functions. It is prescribed to smokers with elevated levels of free radicals, and is more widely used to enhance general health by boosting antioxidant levels. (RDA just dietary sources.)

    Risks: "This is definitely one to avoid," says Collins. "Two major studies were designed to explore the benefits of beta-carotene on protecting against free radical damage and lung cancer risk in smokers. Both trials were terminated when the group on supplements were found to have a higher diagnosis rate and more aggressive forms of cancer. Supplements are now considered more of a risk than a benefit.

    "A diet rich in yellow fruit such as mango, melon and apricot and leafy green vegetables provides all you need."

    Vitamin C is an antioxidant that helps protect cells and targets damaging free radicals. Supplements are prescribed to smokers and alcoholics and are used to combat colds. (RDA 40mg.)

    Risks: "Vitamin C has low toxicity so it's not as dangerous in high doses as many other supplements, but it can cause diarrhoea at levels of 2,000mg a day, which is less than what many people take to ward off colds," says Collins. "There's also controversy as to whether the breakdown of the excessive vitamin C from a high-level supplement - greater than 1g per day - generates free radicals rather than mopping them up. There are many other beneficial nutrients in vitamin C-rich foods that can't be replicated in a tablet.

    "Foods such as tomatoes, peppers, broccoli, sweet potatoes and oranges may contain the same amount of vitamin C as supplements but they have twice as many benefits."

    How safe are your daily supplements? - Telegraph
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