It was nice to see a positive story on vitamins published last month. An American study reported that older people with "mild cognitive impairment" (forgetting names, that sort of thing) did better when taking B vitamins. Specifically they looked at levels of homocysteine and the B vitamins known to affect it.

Homocysteine is one of those molecules that show how complicated nutrition is, and how difficult it can be to get a clear picture. Having a raised homocysteine level is linked to a long list of diseases including autism arthritis, heart disease and Alzheimer's. But is it a cause of these, or just a marker for something else? (that is the story with cholesterol of course.) Anyway it is clear that decent doses of vitamins B6, B12 and folic acid lower homocysteine and also lower the risk of all those diseases.

Vitamin B12 on its own can make a difference in many diseases. We at the BSEM (British Society for Ecological Medicine) have been working closely with the Pernicious Anaemia Society (www.pernicious-anaemia-society.org). Their 3000 members have taught us that personal requirements for B12 vary enormously, and are impossible to predict (blood tests are no help). Some people do fine with an injection every 3 months (the standard NHS treatment), while some need injections weekly, or even more. Tablets hardly work at all, while lozenges that are dissolved under the tongue work for some people but not others.

I've been giving B12 by lozenge and by injection for 25 years now, and I have only once seen an adverse reaction that caused us to stop treatment. Mind you it can sometimes give you pink urine as the red vitamin overflows through the kidneys. This is completely harmless but can be alarming if you're not forewarned.