Inside Yakult's probiotic science culture

In HG Wells’ The War of the Worlds it is not the almighty weapons of humanity that defeated the invading Martians. It is a lack of immunity to the earth’s tiny pathogenic bacteria.

Perhaps the ending would have been unhappier if those war-mongering Martians had fortified themselves with a couple of probiotic yoghurt shots before setting foot on the earth.

“Our body is completely surrounded by bacteria,” explains Dr Satoshi Kudo Yakult Europe’s chief of science, “Because this is the world of bacteria. Good bacteria don’t want to kill us; they give something to the host.”

In an exclusive interview with Stephen Daniells, Dr Kudo explains why the 70 year old philosophy of Yakult’s founding father is more relevant today than ever.

Dr Kudo, a softly spoken man with a kind face and ready smile, added: “The biggest threat to humans today is infectious disease – look at the concerns with swine flu. Think about Spanish flu, or the plague. How many people died?”

Yakult was found over 70 years ago by Dr Minoru Shirota – while working at the Kyoto Imperial University's School of Medicine. He became the first person to successfully culture a strain of lactic acid bacteria with benefits for human health.

“Naturally he thought that if we keep our gut clean, dominated by the friendly bacteria, then infectious disease should be decreased drastically,” said Dr Kudo. “Dr Shirota tried to find relevant strains that could pass through the intestine. That was his idea. And he screened many strains.”

And the one he found now bears his name - Lactobacillus casei strain shirota.

“Maybe this strain is very wonderful and powerful,” said Dr Kudo. “In the old days, it was easy for Dr Shirota to select this as his strain, as his number one. It’s not easy to find a better strain than what we have.”

And according to the company, the 25 million consumers who drink Yakult every day appear to agree. The company now operates in 31 countries across five continents.

“I am sure that a knack of our success was his philosophy: He wanted to save people at an affordable price, and he understood that the gut is the source of health,” said Dr Kudo.

Superman strain?

“If you look at our history and the volume we’ve sold, it is almost uncountable, and no serious cases of adverse events – this is important,” said Dr Kudo. Animal safety studies have backed up these claims, he notes.

“We don’t need to change our strain – it is the safest probiotic and still one of the most popular, maybe number one, so there is no reason,” he adds.

The company is not blinkered to the benefits of the shirota strain, however. In Japan they have a catalogue of other candidate strains, but he notes the company is just holding them. While the shirota strain is the one everyone associated with Yakult, the company did release a bifidobacteria-containing product into the Dutch and Belgian markets. It was not a success and was withdrawn after two years. “The results did not meet our expectations,” he said. “We will of course consider if the circumstances can lead to a relaunch.”

But concentrating on the success of the shirota strain also poses some questions. With potential benefits expanding to ‘beyond the gut’, how then does the company communicate this with consumers?

“Do we say it’s the Superman strain?” asks Dr Kudo. “This is nothing to do with the science, this is more of the commercial issue.”

The health claims issue

Explaining benefits to consumers is one thing, but backing up the claims with science is very much the domain of Dr Kudo. Health claims regulations are also changing the landscape on both sides of the Atlantic for functional foods and dietary supplements.

The European system has caused much concern for many manufacturers, with uncertainty clouding the requirements for the dossiers. “EFSA applied high standards, saying that this is common to US FDA and other systems, and that’s fine,” said Dr Kudo. “We welcome the imposition of high standards, but we definitely need to understand the difference of what the efficacy of a functional food is, and what it is for a drug.

“If they understand these differences, then look at all the scientific papers so that the totality of the evidence is used.

“Placebo controlled is a good experimental design but it is not necessarily always the best one. The totality of the evidence is very important,” he added.

So are we expecting too much from functional foods? “Usually it is very difficult to expect a very sharp or drastic effect for a functional food,” explains Dr Kudo. “What the consumer wants to have is to take it continuously at a moderate one or two serving unit per day, without always knowing or noticing an immediate effect, while their health state is being maintained. This is the objective of functional food.”

“So, to prove the efficacy of functional foods is much more difficult than for a drug,” he said.

Thinking about the future

The list of potential health benefits linked to probiotics continues to bloom with every passing year. Dr Kudo said that initially he was sceptical about “these new functionalities”. That changed when he reviewed a pilot study from Europe looking at the gut-brain axis. “In the old days this was not the target of probiotics,” he said.

“It’s not mysterious that one probiotic strain can influence many health areas, of course not all, but many more than we thought,” said Dr Kudo. “If we stimulate one part it may help obesity, if we stimulate another part it may influence the mental health state. It is no wonder that one strain can influence five ‘beyond the gut’ functions.”

* Dr Satoshi Kudo is leaving as Director of Science for Yakult Europe next week.