Staying healthy in Japan

Health - July 16th, 1982

by Elyse M. Rogers

Salt, Sodium and Soy Sauce

I’ve talked about the prob­lems of salt in the diet before, and explained that it is actually the sodium in table salt (sodium chloride) that is the villain. As foreigners living in Japan, salt is an especially important issue for us because a high salt intake has been linked to hypertension (high blood pressure) and strokes… and Japan leads the world in the incidence of strokes.

Some of you may have read the Mar. 15, 1982, Time Magazine cov­er story about salt, where  it compared a typical U.S. dinner with a Japanese one. The Japanese dinner contained over 4,000 mg of sodium, while the U.S. dinner contained just under 2,000 mg. When you consider that many medical authorities suggest that 2,000 mg per day be your sodium limit, and if you have hyper­tension, 1,000 mg or even 500 mg, you can see that we nor­mally consume a whopping amount of salt in either diet. A teaspoon of table salt, by the way, contains approximate­ly 2,000 mg of sodium.

Because salt and the sodium problem have long been medi­cal interests of mine, I went to a special symposium on the “Relations of Dietary Minerals to Cardiovascular Diseases” that was held in Tokyo, but organized by scientists from North Karelia, Finland. You’re probably wondering what Fin­land has to do with all this, but there is a very logical explanation. The category of “cardiovascular diseases” in­cludes both strokes and heart attacks and, while Japan leads the world in strokes, Finland leads in heart attacks. So both countries have a great deal of interest in any dietary factors which affect the cardiovascular system.

The North Karelia region was chosen for the Finnish study because it has the highest rate of heart attacks in Fin­land. In 1972, there were more than 1,000 severe heart attacks among the approximate­ly 180,000 people in that region.

“The North Karelia Project” was started in 1972 with the aim of preventing or at least decreasing the rate of cardio­vascular disease in that region. The first five-year period of the program ended in 1977 and, after an evaluation, the project was extended until 1982. The results of the community program have been very impressive. From a Finnish government information paper we learn that, “In 1977 there were nearly 20% fewer severe heart attacks than at the out­set of the program [1972]. The number of cerebral strokes fell even more.”

Salt or sodium reduction in the diet was one of the changes in life-style that the project targeted for. This was ac­complished in several ways:

  • Educating the population to the dangers of excess salt.
  • Suggesting less over-all salt usage (i.e. no salt-shakers on the table).
  • Providing commercial food products lower in salt.
  • Introducing a salt sub­stitute—called “New Salt.”

The concept of a new type of salt is a fascinating one. There have been other attempts to replace table salt, but they have failed either because the taste was not really similar or because the product’s safety was questioned. But “New Salt” sounds like it could be a winner. It has a base of table salt, but contains 35% less sodium than pure table salt. The composition of New Salt is as follows:

NaCl (table salt)   65%

KCL (Potassium chloride)   25%

MgCI2.6H20 (or another magnesium salt) 10%

The idea behind this salt substitute is not only sodium reduction. There is scientific evidence suggesting that both potassium and magnesium exert a protective effect against the toxicity of sodium in the body. Studies in Japan have shown a relationship between the acidity of water in Japanese rivers and the distribution of strokes.

In other countries there ap­pears to be this same relation­ship between mineral content of drinking water and cardio­vascular diseases. Drinking hard water, or water with a high concentration of minerals, reduces the chances of cardio­vascular disease; apparently is the high magnesium concentration which provides most of the beneficial effects. Final­ly, growing evidence points to the importance of an appro­priate mineral balance in the body—particularly between so­dium, potassium and magne­sium.

One of the reasons the salt symposium was held in May is that Nissho Iwai (one of Japan’s large trading companies) will be introducing “New Salt” to the Tokyo area very soon. The product should be popular with the Japanese who are becoming aware of the problem of salt in their diet and yet at the same time have a cultural tradition of heavily salted foods such soy sauce, miso soup , pickled vegetables.

For the foreign community, it would be nice to welcome back the salt shaker, but  I’d suggest a bit of caution. There is still limited data on this type of salt substitute and its effects when used heavily. It’s still best to avoid any salt whenever possible, since we know for sure that outright salt reduction does help hypertension. If you have any specific questions or personal medical problems related to salt, you’d be wise to check with your doctor before using the “New Salt” or any salt substitute.