The vitamin myth: do you really need a tablet a day to keep the doctor away?
Forget an apple a day, vitamin manufacturers would have you believe it's important to take daily vitamins to boost your health.
And a surprising proportion of Australians do. Data from the last National Health survey (back in 1995) showed that up to 30% of Australians had recently taken vitamin or mineral supplements – mostly for preventive health reasons.
More recently, the 45 and Up study of more than 100,000 Australian adults found that 19% of men and 29% of women reported taking vitamin or mineral supplements.
But most healthy people don't need to take vitamins. A better safeguard for your health would be to spend the money you save from not buying supplements, on buying more vegetables and fruit.
The Australian Guide to Healthy Eating (AGHE) translates the national dietary guidelines into recommended daily food serves to help Australians eat better, without the need for vitamins or mineral supplements.
In a nutshell, the aim is for adults to have a minimum daily intake of:
- two serves of fruit
- four to five serves of vegetables
- four to six serves of wholemeal or wholegrain breads and cereals
- two serves of reduced fat dairy products
- one serve of lean protein
- a small amount of healthy fats.
The problem is, we just don't follow the advice in the dietary guidelines, or eat like the patterns suggested in the AGHE.
The last National Nutrition Survey of dietary intakes in adults (from 1995 – this is currently being updated) found that we had inadequate intakes of vegetables, fruit, wholegrain cereals and dairy products. We also consumed too much fat, especially saturated fat and over a third of our daily energy intake came from energy-dense nutrient-poor foods, aka "junk" foods.
So what do we do: turn to vitamin and mineral supplements to make up the shortfall? Or try harder to encourage Australians to eat better?
I vote for the second approach because taking supplement is not without risks.
Take lung cancer, for example. Epidemiological research indicated that eating more fruit and vegetables was associated with a reduced risk of lung cancer. After this relationship was recognised, a number of clinical trials then gave people supplements of beta-carotene, given it's a major carotenoid (pigment) in vegetables and fruit.
But the supplements had the opposite effect and actually increased the risk of lung cancer in smokers.
Medical problems that arise due to excessive intakes of vitamins and minerals are almost always due to intakes of supplements. To develop toxicity from vitamins in food you'd have to eat excessive amounts of specific foods such as carrots (which could make your skin turn yellow) or liver (vitamin A toxicity would leave you with blurred vision, dizziness, nausea and headaches).
There are, however, people with health conditions or in a particular life stage when they really need vitamins. This includes people with chronic medical problems (such as cystic fibrosis, coeliac disease, pancreatitis), people on restrictive diets to achieve rapid weight loss, those with conditions that interfere with their ability to eat properly.
Women planning a pregnancy also require additional nutrients. Folic acid supplements are strongly recommended in early pregnancy to reduce the risk of having a baby with neural-tube defects such as spina bifida.
Let's leave vitamin supplements to those who need them, and call this myth busted.
Clare Collins is a professor in Nutrition and Dietetics at University of Newcastle.