Vitamin B6, Magnesium and Autism Ranking: Insufficient/Mixed evidence

Suppliers and Availability


Vitamin and mineral supplements are available from a wide range of suppliers including health food stores, chemists and pharmacies, professional health care providers and online stores. 

If you are contemplating taking any kind of dietary supplement, you should seek advice from a GP, pharmacist or dietitian. The British Dietetic Association has information about qualified dietitians in the UK.


There are no formal, internationally validated registered qualifications for most people who provide dietary supplements.   
However, in the UK, the quality of dietary supplements is regulated by the Medicines and Healthcare Products Regulatory Agency, if they ‘contain a pharmacologically active substance or make medicinal claims (claims to treat or prevent disease, or to interfere with the normal operation of a physiological function of the human body) ...’

In the UK certain supplements are considered to be foods and will therefore be regulated under general food laws by the Food Standards Agency and Department of Health. Others will be regulated as a medicine by the Medicines and Healthcare Regulatory Agency (MHRA).

All herbal medicines placed on the UK market must have a Traditional Herbal Registration (THR) or a marketing authorisation (previously known as a product licence). The MHRA now defines individual herbal medicines as either registered traditional herbal medicines or licensed herbal medicines.

In the USA dietary supplements are not classed as drugs, but the Food and Drug Administration is responsible for taking action against any unsafe dietary supplement product after it reaches the market. 

21 Dec 2018
Last Review
01 Dec 2018
Next Review
01 Dec 2021