In the 1970s, David Horrobin gave up his job as professor of medicine at Montreal University to introduce the world to the evening primrose. Thousands of women suffering menstrual tension now swear by his oil, and the restorative powers of the gamma-linolenic acid (GLA) it contains. Then came borago officinalis.
Most people use borage for flavouring fruit cocktails or stews. But it is more than twice as rich in GLA as the evening primrose. If it's GLA you're after, borage oil could be your tipple.
Dr Horrobin has responded by accusing rivals promoting it of duping women, selling pigs in pokes and marketing 'unstable and potentially toxic products'. His competitors - Roche Products and Seven Seas - say he is scaremongering and 'mud-slinging' to prop up an ailing business.
Sales of evening primrose oil in the UK are booming, up from pounds 17m in 1991 to pounds 36m last year. The world market is worth pounds 200m. Scotia Pharmaceuticals, which was founded by Dr Horrobin and sells Efamol, once having the market to itself, has seen its share shrink to about a quarter. Borage oil - advertised as 'nature's richest source of GLA' - is partly to blame.
GLA is a fatty acid which some people's bodies are less efficient at producing. There is evidence - disputed - that it may help to alleviate pre-menstrual breast pain and some forms of eczema. What is not disputed is that borage oil contains 25 per cent GLA and evening primrose about 10 per cent. This makes it about 15- 30 per cent cheaper.
Dr Horrobin claims it has been inadequately tested, has the wrong biochemical balance and 'far from being desirable, might actually be dangerous'.
Bent Henriksen, managing director of Pharma Nord, which produces borage-based supplements, said: 'Everybody in the industry thinks he is panicking.'
The industry fears the controversy could damaging the whole market. Its critics hope it will. Dr Thurstan Brewin, chairman of HealthWatch, which monitors alternative medicine, said last week: 'You get thousands of people swearing by something, and everyone thinks there must be something in it, but they are absolutely wrong. It's a psychological effect.'