Monday, June 08, 2009

Probiotic supplements have 'no proven benefit for healthy people'

Good to see some reasonable skepticism

Probiotic drinks are of no benefit to healthy people and may harm those with low immune systems, a leading microbiologist has warned. Michael Wilson, Professor of Microbiology at University College London, said there were some cases when topping up on "good bacteria" could help recovery from illness, but understanding of the supplements is "shaky" and needs a more robust scientific investigation.

"There are certain instances when probiotics are useful but the problem is there's no regulation," Prof Wilson said. "They are regarded as food supplements not medicinal products – anyone can get a suspension of bacteria and market it as a probiotic," said Prof Wilson, speaking at the Cheltenham Science Festival. "With medicinal treatments, the pharmaceutical industry makes sure the things they produce are safe."

He said that there was some "instinctive sense" that adding to the gut flora will help with adverse events. In recent years, probiotics have been promoted as a healthy food supplements, in the form of yoghurts, drinks and capsules, and the market is worth an estimated £200 million in Britain.

Clinical trials have shown that eating live bacteria can help sufferers of certain illnesses, such as antibiotic-associated diarrhoea, and there is evidence they can help women who have recently given birth to lose weight. However, according to Prof Wilson, for people with compromised immune systems, increasing the bacterial load could lead to health problems.

"No bacterium is totally innocuous. If you are healthy there is probably no harm in taking probiotics, but there is also no benefit. But to increase the bacterial burden if you are immuno-compromised is asking for trouble," he said.

A spokesman for Yakult, one of the leading probiotic brands, disputed Prof Wilson's warning. "We have 75 years of studies, carried out by independent scientific research bodies in the UK, Europe and Japan, including human trials, which have all demonstrated the health benefits of supporting the gut flora with Yakult."

A spokesman for Danone, the company which produces Actimel and Activia probiotic yoghurts, added: "The efficacy of these products has been shown in many studies and the results have been published in highly reputed scientific journals. "Most recently an independent study, published in the British Medical Journal, showed a significant reduction in the incidence of C difficile-associated diarrhoea in hospitalised patients who drank Actimel twice a day."


There's more to breastfeeding than meets the eye

ANIMAL milk production was biochemist Peter Hartmann's specialty as a young scientist, but when Britain joined the common market in the early 1970s and European dairy products displaced Australian ones, his funding collapsed and he began applying his knowledge to humans. At the University of Western Australia, he focused instead on that "incredible organ", the lactating breast. "At that time, breastfeeding was at the lowest point ever in Australia, it wasn't seen as the 'in' thing to do research on," Hartmann says.

Last month, it was announced that Hartmann, with computer expert and UWA pro vice-chancellor (research and research training), Robyn Owens, had been awarded the $160,000 British Rank Prize for nutrition. Hartmann's desire to work out a simple, effective way of measuring breast volume, and then milk volume within the breast, was facilitated by Owens's expertise in adapting computer technology called "Moire topography". This method involves projecting stripes on to a breast and measuring the distortions caused by the shape of the breast, which allows calculation of volume.

"One of the stories here is that cross-disciplinary collaboration is very powerful. In WA, these collaborations are easier because you can be at an institution within 10 or 15 minutes," Hartmann says. This teamwork made possible a world of discoveries about breastfeeding. These ranged from basic research such as establishing that humans lactate differently from dairy cows and laboratory animals, [Another example of the often-poor generalizability from animal models] to present work growing breast tissue from stem cells produced in milk.

And while it was already relatively simple to work out how much milk a baby was receiving at each feed - by weighing the infant before and after - that gave no clue about how much each breast was producing, and the capacity of each breast. "One of the things our research clearly showed was that the baby was choosing how much milk to take at each feed, so we could say a baby's appetite varied, they were not always 'clearing their plates'," Hartmann says.

It transpired that the more the baby drained from a breast, the more the breast produced. And that breasts operated independently of each other. One might be very full for one feed and the other much less so, but the position could be reversed from feed to feed. It was also possible to work out how empty a breast was by the amount of fat in the milk. If the milk produced was fatty, the breast was giving up its last reserves.

There is much more to do and know, Hartmann says. "We don't have any (medical) specialty in looking at this important function, so if you have a problem and go to your GP and he can't help, there's nowhere else to go."


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