The story of a man who ended up needing a liver transplant after taking green tea capsules has brought the topic of dietary supplements back into the news. What are some of the dangers of supplements and what are the health benefits?
When Jim McCants started taking green tea pills he had hoped he was giving his health a shot in the arm.
Instead, it appears the pills caused such serious damage to his liver that it required an urgent transplant.
Experts point out that experiences like that of Mr McCants, are “extremely unusual”.
In the UK, supplements are subject to EU regulations over their safety and the health claims manufacturers make about the products.
Approved supplements bought from reputable businesses are almost always going to be safe, provided the manufacturer’s instructions are followed, doctors say.
But it is wrong to assume that food supplements do not sometimes have the potential to be harmful, says Dr Wayne Carter, from the University of Nottingham.
If you take supplements in quantities above recommended levels there are risks.
While in many cases excess levels of a supplement will be excreted, there is the potential for it to be toxic, particularly to the liver, which detoxifies the substances we consume.
“I think sometimes the idea that people take on board is ‘this is good for me, therefore if I take even more of it, it will be even better’,” Dr Carter says.
Supplements for child health
There are some supplements that are widely acknowledged by experts to be of benefit across the population.
The NHS recommends that women who are thinking of having a baby should have a folic acid supplement, as should any pregnant woman up to week 12 of her pregnancy, to prevent common birth defects in babies.
This includes those who are frail or housebound or usually wear clothes that cover up most of their skin when outdoors.
The rest of the population is advised to consider taking a Vitamin D supplement.
‘Constantly evolving science’
Dr Jacobs said supplements are also important for people with either restricted diets or allergies.
For example, the NHS says vegans might need a vitamin B12 supplement, because it is only found naturally in foods from animal sources.
However, in many other supplements the evidence of there being a benefit for most people is less clear.
For example, the NHS says that most people do not need to take other vitamin supplements and can get all the vitamins and minerals they need, apart from vitamin D, from a balanced diet.
Dr Carter said his own advice would be for people to look at what kind of scientific evidence there was in support of a particular supplement before taking it and check whether there are any warnings.