Not enough is known about long-term safety of "functional foods"

May 18 2007

So-called 'functional foods' need to be systematically monitored because not enough is known about their long-term safety and effectiveness, say a group of scientists writing in the British Medical Journal.

Functional foods are modified foods which claim to improve health, quality of life and/or well-being, for example, yoghurts or margarines which improve the health of your gut or heart.

These foods are rapidly increasing in popularity. Between January and April 2005 200 functional foods were launched onto the market and with a turnover of £316 million in 2005, the active health-drink market is one of the fastest growing in the UK.

Current EU rules focus primarily on evaluating the safety of these foods before they reach the supermarket. As yet, the Dutch scientists say, there are no regulations dealing with aspects which arise after these products have been marketed.

There is “little understanding of the circumstances under which the foods are eaten, whether target groups are reached, and if targeted education programmes or health policies should be recommended. Very little is known about exposure, long term or otherwise, and safety under free conditions of use, and whether and how functional foods interfere with drugs designed for the same target”.

Nynke de Jong and her colleagues from the National Institute for Public Health and the Environment in the Netherlands stress that to date there is no evidence that these foods cause harm, although the data is limited to 5-6 years of use. But they say scientific developments with food and pharmacology are ongoing and so data supported assessments are now possible.

They pay specific attention to the group of products enriched with phytosterol and stanol which work to reduce the amount of ‘bad' cholesterol entering the bloodstream. These are intended for people with mildly elevated cholesterol levels. Within the population as a whole these people are often unaware of their cholesterol level. It therefore follows say the writers that these enriched foods may only be eaten by people with much higher levels of cholesterol, who know they have a problem and are thus more likely to be taking medication as well. This, they say, inherently increases the potential for interactions with the drugs.

They warn “functional foods may influence the effectiveness of drugs and patients' compliance” and list a number of areas which need further study, for example there is some concern that phytosterols could increase fatty deposits in the arteries.

The scientists say a systematic monitoring programme would mean the public could ultimately have access to practical and unbiased information about when, how and if to eat functional foods. They conclude “we need to invest more in finding out what functional foods can contribute to individual and public health in relation to the promises made by manufacturers”.