Supplements are worth more than $26.9 billion to the US economy. But new research suggests taking high doses of certain supplements could actually do more harm than good.
Accumulating evidence suggests that calcium supplements, widely used to prevent and treat osteoporosis (despite generally disappointing results on fracture rates), may actually increase the risk of heart attack and stroke. High doses of calcium are also a risk factor for kidney stones. On the other hand, calcium intake via a high calcium diet helps to lower blood pressure and may cut the risk of colorectal cancer.
Food sources include dairy products and fortified alternatives, tofu made with calcium sulphate, nuts, seeds, dried fruit, legumes and Asian greens.
A major antioxidant in the body, vitamin E supplements are used in the hope to prevent cancer and cardiovascular disease. However, high doses may increase the risk of cancer, heart failure and early death. A trial of more than 35,000 healthy men found that the risk of prostate cancer increased by 17 per cent in those who took a daily dose of 400 international units (IU) of vitamin E. But getting this vitamin from foods is not harmful. Frequent use of nuts, for example, is consistently associated with fewer heart attacks.
Food sources include nuts, seeds and vegetable oils like sunflower.
Because it has been shown to reduce the risk of neural tube defects in babies, folic acid fortification of food has become common. Yet concerns exist about supplementing everyone with this vitamin. High doses appear to increase colon polyps (a precursor to cancer) and are linked directly with cancers of the breast, prostate and colon. Folic acid supplements can also mask vitamin B12 deficiency. However, naturally folate-rich foods protect against chronic diseases.
Food sources include green leafy vegetables, legumes, fruits such as oranges and strawberries, and juices.
Supplements are not magic bullets. Either too little or too much of a nutrient can be harmful, particularly if it is taken in an isolated form. The safest way to guard against ill health is to base your diet on a diverse range of nutrient-rich foods.