Takara Bio is planning to research the use of lesser yam in functional foods, following research that indicates a variety cultivated in Japan has more than 200 times the content of the plant steroid diosgenin than other domestic varieties.
The company investigated the diosgenin content of 80 different kinds of yam are grown in Japan, where the tuber forms part of the staple diet. The dioscorea esculenta variety, which originates from Vietnam and is grown around Okinawa in Japan, was found to have a far superior diosgenin content and also boasts good viscosity and a sweet taste.
Diosgenin has a structure similar to DHEA (dehydroepiandrosterone), which is also derived from yam and sold in dietary supplements in the Unites States. It is thought to play a role in maintaining hormone balance.
Occurring naturally in the blood of young people, levels of DHEA have been shown to peak between the ages of 20 and 30 years, but decrease progressively thereafter. It is known to break down into various sex hormones, including testosterone, which helps build muscle.
Its uses, particularly amongst older Americans, include including maintaining muscle strength and strong bones, boosting immunity, and improving mood and sleep patterns.
DHEA is a $15 million product in the United States and has been on the market for 20 years. It is a common misconception that DHEA is an anabolic steroid, which has led for calls from some quarters for it to be classified as a controlled substance. In fact, it is an adrenal steroid and the US supplements industry has been lobbying hard against legislation that would have it removed from the consumer market.
Takara Bio will be presenting the full results of its research into yam varieties and diosgenin at the 60th Annual Meeting of the Japanese Society of Nutrition and Food Science in Shizuoka at the end of this week.
The Japanese functional foods market is arguably the most developed in the world, as it was the first country to introduce health claims in the 1980s. Ingredient trends see in Japan may take up to three years to be picked up in the US and European markets.
According to industry analyst Paul Yamaguchi, the Japanese nutrition market is valued in the region of US$27 billion, but FOSHU foods (foods for specified health uses) account for only $6 billion of this. Non-FOSHU functional foods account for $11 billion, and dietary supplements around $11 billion too.