Japanese Researchers: Soy Compound Eases Salt's Harm to Blood Pressure and Memory in Mice

Researchers at Fujita Health University in Japan have determined how a soy-derived compound called LPC70 reduces the effects of excessive salt intake on blood pressure and brain function in mice. The study appeared in the journal Neurochemistry International, and its authors suggest the substance could eventually serve as a functional food ingredient. Too much salt is already a major public health concern because of its link to hypertension, but it may also affect memory, thinking and emotional well-being.

What LPC70 is

LPC70 is a form of soy lysolecithin in which lysophosphatidylcholine makes up more than 70% of the phospholipids. Earlier mouse experiments showed it could ease salt-related high blood pressure and cognitive problems, but the mechanisms were unclear. In the new work, a team led by Professor Akihiro Mouri and Dr. Hisayoshi Kubota, with Dr. Kazuhiro Kagotani, examined its effect on prostaglandins. These signaling molecules are made from arachidonic acid and help regulate blood pressure; in the brain they can either protect nerve cells or contribute to harmful processes.

Findings in mice

Mice fed a high-salt diet developed elevated blood pressure, interacted less with other mice and had trouble recognizing objects they had seen before. Their general movement and anxiety-like behavior did not change substantially. When LPC70 was added to their diet, blood pressure improved and the animals performed better on social interaction and object recognition tests.

In the kidneys, the high-salt diet increased expression of COX-2 and the PGE2 receptor EP3, both of which may contribute to hypertension; LPC70 reduced these increases. In the prefrontal cortex, a region important for thinking, memory and social behavior, salt lowered expression of DP1, a PGD2 receptor involved in protective, anti-inflammatory signaling. LPC70 restored it without altering DP2, a receptor linked to potentially harmful effects. Mice on the salty diet also had lower circulating arachidonic acid, yet prostaglandin levels, including PGE2 and PGD2, rose after LPC70.

Limitations

The findings come from animal experiments, so clinical studies are required to establish whether humans would gain the same benefits. The research was funded in part by Tsuji Oil Mills Co., Ltd, a company that develops naturally derived food ingredients, along with several science foundations and Japanese government programs.