DESPITE the fact that many of us swallow a daily multivitamin pill their long-term effects have been unknown – until now. The first study of its kind suggests taking a daily supplement can lower the risk of developing cancer in men. Regular use for more than a decade has been shown to cut males’ chances of suffering from the disease by eight per cent, according to researchers at Harvard Medical School. And experts believe that the same is likely to be true for women.
But which supplements do we really need and can any be harmful when taken in excess? Here, leading nutritionist and health writer Dr Carina Norris shares her insights into the value of vitamin and mineral supplements. She reveals the truth about which offer the greatest benefits and which we should avoid.
VITAMINS
Vitamin A
This is needed for healthy skin and vision and supports the immune system. It also acts as an antioxidant, protecting our body’s cells from damage. The recommended intake is 700 micrograms a day for men and 600 micrograms for women. But vitamin A is stored in the body, so if you take too much it can accumulate to dangerous levels and cause liver damage. For this reason you need to check all the sources you could be getting vitamin A from, such as a multi-supplement, cod liver oil (very high in vitamin A) and an antioxidant supplement, as well as your diet – if you eat liver, for example.
B vitamins
A group of vitamins that includes B1, B2, B3, B6 and B12 and is involved in the release of energy from food, making blood cells and keeping the nervous system healthy. These are water soluble and aren’t stored in the body. Any excess is flushed out in the form of urine so taking them as part of a multivitamin is not harmful.
Folic acid Another member of the B vitamin group which is vital for pregnant women or those planning a pregnancy as it reduces the risk of neural tube defects such as spina bifida in the baby. There’s also evidence that it might reduce the heart disease risk in the general population. The recommendation is 200 micrograms; double this for women planning a baby and for the first three months of pregnancy. Any excess is flushed out in your urine.
Vitamin C
Vital for a healthy immune system and wound healing, this also helps you to absorb iron from food. However, evidence that it helps prevent colds is inconclusive. The official recommendation is just 60 milligrams but I’d consider this the bare minimum to prevent deficiency and you need more for optimum health. That said, if you eat at least your five a day fruit and veg, you should easily get enough. Any excess will be flushed away in your urine.
Vitamin D
This is vital for healthy bones and teeth as it helps the body absorb and use calcium. But I think we’re going to be hearing a lot more about this vitamin. Studies suggest that low levels could contribute to a variety of conditions, including cancer and Multiple Sclerosis.
We get most of our vitamin D from a reaction caused by the action of sunlight on the skin but research suggests that many of us aren’t getting the optimum exposure due to the pitiful amount of sunshine we get in this country.
There’s no official recommendation for most people, though pregnant and breast-feeding women are advised to take a 10 microgram supplement, as are the elderly.
It’s certainly worth taking a multivitamin containing vitamin D but don’t take to excess. It is stored in the body and can build up to harmful levels.
Vitamin E
It is involved in supporting the immune system and it’s so unlikely that you wouldn’t get enough from a normal diet that there is not even an official recommendation for it.
Vitamin K
This will help the blood to clot and is needed for healthy bones. The best food sources for providing it are eggs, fish oils, dairy products, green leafy vegetables and asparagus. Vitamin K is also produced naturally by harmless bacteria in our gut. Again it’s not a vitamin I’d recommend people taking singly, though it’s useful to find in a multi.
MINERALS
Iron
Needed to make the red blood cells that carry oxygen around the body, and to prevent anaemia. Iron from animal sources (such as lean red meat, oily fish and egg yolks) is much better absorbed than that from vegetarian sources (such as green leafy vegetables, nuts and pulses), though you can enhance absorption by eating your iron-rich foods with vitamin C-rich sources such as tomatoes or a glass of orange juice.
Insufficient iron is one of the commoner nutrient deficiencies. Women who have heavy periods may need a supplement but overdoses are dangerous so if you think you may be anaemic you should see your doctor for a blood test. They can prescribe supplements if necessary.
Vitamins
Calcium
Essential for building and maintaining healthy bones and teeth, this is important to help prevent osteoporosis in later life, especially in women. The best food sources include dairy foods, sardines, salmon and green leafy vegetables.
The recommendation is 700 milligrams for adults but more for breast-feeding women, who need it to produce milk, and teenagers, who are at peak bone-building stage. If you take a supplement, calcium citrate is better absorbed than calcium carbonate.
You need to ensure you’re getting enough vitamin D to help you to absorb your calcium.
Zinc
This is another important immune nutrient and it’s also needed for healthy growth and development, as well as sperm formation in men. There’s some evidence that taking zinc lozenges could help treat colds but most people don’t need to take a supplement as it’s easy to get from the diet.
Magnesium
As well as helping the body deal with stress this aids muscle function and is also needed for healthy bones. Some studies suggest that women suffering from Premenstrual Syndrome have low magnesium levels and that taking a supplement could help. However, you should ask your GP for guidance.
Selenium
A vital booster for protection against heart disease and cancer. Some research suggests that levels of selenium in the soil are decreasing and this could make it harder to get enough of this mineral from food. I certainly wouldn’t recommend individual selenium supplements, though good multivitamins will generally contain it.
Fish oil
This is one of the supplements I take, even though I generally eat oily fish the recommended once a week. There’s strong evidence that the omega-3 essential fatty acids in fish oil can reduce our risk of a range of conditions, most notably heart disease, but also depression, dementia and chronic fatigue syndrome. However, the doses used in these studies were high. I’d suggest taking a fish oil supplement with around 500 to 1000mg omega-3s per day.
Pregnant women need to be more careful about the amount of oily fish they eat, as they can contain low levels of pollutants that could harm the unborn baby.
It’s important to note the difference between cod liver oil and fish oil. Cod liver oil (like all liver) is extremely high in vitamin A and to get any significant benefits for your heart you’d have to take more than would be wise. But if you take fish oil, extracted from the flesh of the fish (not just the liver) you can safely get enough of these beneficial omega-3s.
Fish oil is a supplement where quality and method of production is key. Ensure that the fish used comes from unpolluted seas.
Probiotics and Prebiotics
Probiotic supplements top up the friendly bacteria that inhabit everyone’s gut and can be helpful if you have been taking antibiotics which are designed to kill all bacteria – friendly or not.
Most people take them in the form of little yogurt drinks but you can also buy them in capsules or tablets. Studies have also suggested that they can help in cases of Irritable Bowel Syndrome (IBS). Research is finding more and more things that these beneficial bugs are responsible for.
Prebiotics are “food” for the friendly bacteria and you can buy prebiotic supplements as well as foods fortified with prebiotics.
