Forget everything you think you know – we uncover the truth on what you should and shouldn’t be taking
It seems every week there’s a new headline declaring vitamin and mineral supplements are either vital for health, or a complete waste of money. But what’s the truth? Around 10 million people in the UK take them – they can’t all be wrong can they? “Vitamin and mineral supplements may be useful but they should not be taken as an excuse to avoid eating a balanced diet including fruit and vegetables,” says nutritionist James Collier. Common sense, most will agree. So where’s the harm in popping pills if the jury’s still out? Well, it comes in the form of the combinations you may be taking, and even the foods you take them with. “For example,” says James, “calcium can inhibit the absorption of iron supplements, so avoid taking these two together. Also, don’t take iron tablets with dairy products like cheese or yoghurt as these are rich in calcium.
“Iron and zinc absorption are also impaired by phytic acid which is found in oats, rice, wheat and some seeds, so avoid taking your iron and zinc at the same time as these foods.
“However, vitamin C boosts iron and zinc absorption, so take them with vitamin C supplements or with foods rich in the vitamin, like citrus fruits, fresh greens, berries and potatoes.
“Vitamin D and calcium work well together for bone health; and it’s also worth looking at vitamin K2 supplements for healthy bones.
“High doses of the retinol form of vitamin A may reduce vitamin K absorption, but the amounts in typical multivit formulas will not have much effect. All the B vitamins (thiamin, riboflavin, niacin, pantothenic acid, vitamin B6, biotin, folic acid, choline and cyanocobalamin) work synergistically and are ideal in a single supplement,” he explains.
So we know what works with what, but what about overdoing it – can too many vitamins or combinations be toxic to the body? Could we, in supplementing to improve our health, be inadvertently poisoning ourselves? Sure, it is possible, but unlikely, says Dr Carel Le Roux, professor in metabolic medicine at Imperial College, London and nutrition advisory board member for global nutrition brand Herbalife: “For the fat soluble vitamins such as A, D, E and K toxicity can ensue, but this only happens at very high levels which are difficult to achieve with a balanced diet together with sensible supplementation.
“In general the body is extremely robust and can handle most combinations of vitamins and minerals. Water soluble vitamins especially such as the vitamin Bs and C can easily be excreted if excessive amount are consumed. The body is also good at storing vitamins and minerals for use in periods of reduced supply. This ensures that blood or even cellular levels of the vitamins and minerals are very rarely low. In the small number of patients where the vitamin and mineral levels become low this means that there is not only a deficiency in the blood, but most likely a body wide deficiency. In these cases very specific supplementation under medical supervision is required to quickly and safely rectify the situation.”
You should aim to take your supplements with food – this is particularly important for the fat-soluble vitamins A, D, E and K, which are only absorbed with fat and then stored in the fat cells until they are needed. But there are certain foodsupp combos that should be avoided, as nutritional medicine expert Dr Sarah Brewer explains: “Polyphenols in tea and coffee (like tannins and chlorogenic acid) bind to iron and other minerals and reduce their absorption. In fact, coffee can reduce iron absorption by up to 80 percent if drunk within an hour of a meal. These beverages also reduce the bioavailability of other minerals such as zinc, magnesium and calcium. In general, drink water with meals and wash down supplements (and medications) with water or orange juice, unless you’re otherwise instructed by a professional.
“Bran and phytates (found in unleavened wheat bread) bind minerals in the gut so they remain unabsorbed,” she explains. “This can reduce uptake of iron by as much as 65 percent, as well as reducing absorption of zinc, calcium and manganese. This problem does not occur with leavened (yeast-raised) bread, as yeast enzymes break down phytates so mineral-binding does not occur.
However, high-fibre diets, which speed the passage of food through the bowels, will reduce the amount of minerals absorbed, especially calcium. If you are following a high-fibre diet, ensure you obtain enough calcium from milk and dairy products, broccoli, nuts, seeds and pulses,” she says. And if you are taking pharmaceutical drugs, you could be depleting your body of vital nutrients: “If you are taking long-term antibiotics (for acne, for example) you will benefit from increasing your intake of vitamin K (found in cauliflower, broccoli, dark green leafy vegetables and fermented foods such as soybean natto). Antibiotics interfere with the action of vitamin K in the body, and also kill probiotic bacteria in the large intestine that produce vitamin K so that levels needed for healthy blood clotting are reduced. Tetracycline antibiotics also bind to calcium found in dairy products. This can decrease the absorption of both the antibiotic and calcium,” says Sarah.
And if you thought taking pills for indigestion would be helping your gut, think again: “Antacids and acidsuppressing drugs lower the level of acidity in your stomach. This can affect the solubility of minerals such as calcium, iron, magnesium, zinc and phosphate and reduce their uptake further down the gut,” says Sarah. “Absorption of vitamin B12 may also be affected.”
“ACE inhibitors used to treat high blood pressure or heart failure appear to deplete zinc levels and can lead to a deficiency. It is therefore a good idea for people taking it long-term to increase their intake of zinc-rich foods such as red meat, seafood (especially oysters), offal, whole grains (processing removes most of the mineral zinc) and pulses,” says Sarah.
“Aspirin increases the loss of both vitamin C and zinc in urine. Those on long-term aspirin therapy might benefit from taking supplements providing vitamin C and zinc daily. Non-acidic forms of vitamin C (e.g. ester C) will reduce the risk of acid indigestion).
“Oral contraceptives appear to deplete the body’s stores of vitamins C, B group including folic acid, magnesium and manganese, but on the flip side, may lead to increased levels of iron, and vitamin A. The clinical importance of this is unclear, but an appropriate folic acid and B group supplement may be sensible.
“Statins taken to lower cholesterol level switch off production of co-enzyme Q10, and this may contribute to some of the muscle side effects that can result from treatment. A supplement (like ubiquinol 100mg) may help to overcome this. Levels of vitamins D and E are also lowered by statin therapy and a multivitamin may be a good idea.”
And if you are in any way unsure, Sarah’s final piece of advice is to make sure you read the smallprint: “If you are taking any conventional or traditional herbal medicine, always read the patient information leaflet provided before taking any supplements to check there are no known contraindications to taking them together.”
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