The news today that a TV ad for Danone's Actimel yoghurt has been banned by the UK's advertising watchdog provides a further example of the controversy that has dogged the probiotics sector. Ben Cooper reports on a market that has somehow managed to attract growth and scepticism in equal measure.

As the functional food boom has gathered pace, consumers have become increasingly accustomed to being bombarded with health claims. And arguably no area of the functional market typifies this more than the probiotic category.

However, the volubility of the probiotic sector has been matched by the controversy its claims have attracted, and in recent weeks and days some of those problems appear to have come home to roost.

The news today (14 Oct) that the Advertising Standards Authority, the UK's advertising watchdog, has banned a TV ad for Danone's Actimel yoghurt because the evidence Danone provided did not uphold claims that the product could help protect "normal, healthy school-aged" children against common childhood illnesses, provides another blow to a somewhat beleaguered sector.

Two of the five trials submitted by Danone were carried out on children in India suffering from acute diarrhoea or receiving medication for chronic gastritis-related illnesses. The ASA concluded that neither was suitable for use in support of Danone's claim.

This ruling follows the settlement last month of a 2008 lawsuit against Dannon, Danone's US subsidiary, over the advertising of its Activia and DanActive yoghurts, accusing the company of false advertising in overstating the products' health attributes. Dannon agreed to set up a fund worth US$35m to reimburse consumers and change the labelling and marketing of Activia and DanActive to "increase the visibility of the scientific names of the unique strains of probiotics that are in each of these products".

Last week, the probiotics category received another major setback as the European Food Safety Authority (EFSA) came down particularly heavily on probiotic ingredients in the first phase of the review it is conducting under EU regulation 1924/2006 on nutrition and food health claims.

In total, EFSA issued 523 opinions, only around a third of which were favourable. But for probiotics specifically, the picture was far worse. Of the 180 probiotic cases examined, nine were rejected as having "negative" opinions on their health claims, while a further 105 were "not sufficiently characterised" and had not provided enough evidence of their effects.

Danone and Yakult withdrew their claims before the EFSA evaluation and have since resubmitted them; those results will not be available until next year.

The issue of validating health claims is a sensitive one for many areas of the food market, but arguably there are no categories where it is more pertinent than probiotics.

A newly published just-food report, Global Market Review of Probiotics - Forecasts to 2013, articulates the dilemma this creates for marketers of probiotic products. "Many of the trends currently affecting the global probiotics market are related to the global regulatory environment, which is generally becoming stricter and affecting which health claims manufacturers can make for their products," the report states.

This is reflected in consumer and media scepticism towards the products. While the report points out that around 30% of the global population buys into the probiotic dairy sector on a regular basis, this penetration is particularly high in Asia Pacific countries, notably Japan. The report adds: "Elsewhere, fairly high levels of consumer scepticism still exist regarding the efficacy of probiotics, and this is thought to be holding back the market."

The aftermath of the EFSA announcement last week has also perfectly illustrated the media scepticism towards probiotics. In spite of the fact that the World Health Organization (WHO) defines probiotics as "live micro-organisms which, when consumed in adequate amounts, provide measurable health benefits", the products have found it hard to shrug off a slightly cranky, 'quack-cure' image in the media.

In reporting the EFSA story, an article in the Guardian likened today's functional food boom to the hyperbolic and often totally spurious claims made by food and medicine marketers of the 19th century. Back then, those products capitalised on the gullibility of ill-informed consumers. Last week The Independent wrote: "Thirty million shoppers have swallowed the claims for probiotics as enthusiastically as the sweet fermented milk in the belief that "good bacteria" will defeat "bad bacteria" in epic microscopic battles inside our bodies."

The leading consumer rights group, Which?, also weighed in with a hefty blow against functional food claims following the EFSA ruling. "Clearly many food companies are exploiting people's interest in improving their health, often over-charging them for alleged health benefits which can't be proved," said its chief policy advisor, Sue Davies.

Probiotic health claims have also been questioned by academics. Most recently, the effectiveness and even the safety of probiotics were called into question by Professor Michael Wilson of University College, London.

For all the controversy, the huge success of the probiotics in Japan, where the products were first pioneered, and the growth and potential of the market generally has attracted major food companies into the sector. In addition to Danone, the probiotic market is dominated by a number of multinational dairy operators, such as Nestlé, Yakult Honsha and Müller.

In 2008, the global probiotics sector (including both foodstuffs and supplements) was worth over US$15.7bn, representing over 18% of the global functional foods market. Since 2003, the global probiotics market has more than doubled in value terms, and is currently rising by almost 15% per annum, according to the just-food report.

While the report notes some interesting divergence in the level of consumer acceptance of health claims across different nationalities, with consumers in the Netherlands and the UK for example more distrustful of claims than Scandinavians, it is clear from recent events that consumer confidence is a key issue for probiotics. Recent studies from the European Commission suggest that 77% of European consumers do not trust health and nutrition claims made by food manufacturers on their products.

"The global probiotics market is currently at a strategic turning point," the report states. "The next few years are likely to prove vital, as companies balance the changing regulatory environment with growing consumer awareness of probiotics and technological advancements extending the presence of probiotics into other product sectors."

The report forecasts that the market value will increase by almost 38% between 2008 and 2013, but it also predicts a drop in growth from recent levels over the next couple of years.

Characterised by both growth and controversy, the probiotic sector appears in a way to defy logic, but the events of the past few weeks have suggested the latter still has the potential to undermine the former.