14.3: Thiamin

In Chapter 11, we had a peek at the thiamin-deficiency disease beriberi in discussing Eijkman’s discoveries in Indonesia, and Funk’s curative extract of rice polishings. But even before their discoveries, a Japanese Naval physician Kanehiro Takaki had shown he could cure beriberi by diet.

When Commodore Perry opened up Japan in 1854, one result was a new Japanese interest in both overseas commerce and sea-borne defense. Japan began to send ships to sea for long periods. This placed greater emphasis on the more easily preserved foods of their culture, with rice as the staple. Also, the overseas commerce of Japan led to the importation of finely milled rice. In short, the Japanese Navy began to travel longer and to depend more on highly polished grain for nutrition. And they came down with beriberi.

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We get much of our thiamin from enriched grains and the products made from them (e.g., bread, tortillas, pastries) and fortified cereals. Compared to many other vitamins, there aren’t many foods that naturally have much thiamin—pork is one of our richest sources.

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As the work of Eijkman and Funk later indicated, the culprit was the polished rice—the thiamin lost in polishing had provided most of their dietary thiamin. The long time at sea magnified the problem, leading to beriberi.

In 1880, Japan had 4,956 sailors; 1,725 were lost to beriberi. In 1881, government annals show 4,641 naval personnel, with 1,165 lost to beriberi. In 1882, navy personnel totaled 4,769; beriberi losses were 1,929.³

Navy physicians were instructed to look for a microbe, which it was felt must be causing the plague. There was a sense of urgency. Even among the survivors, as many as three-fourths of them were too sick to fulfill their duties.

Takaki noticed that British ships didn’t have this problem. And he observed that one difference between the two navies was their diets. At first, his idea that food played a part was ridiculed and rejected. But, finally, a desperate naval command allowed Takaki to experiment.

Two ships were chosen. One was given the usual rations. The other—since Takaki had no idea just which food made the difference—was outfitted with a duplicate of British provisions, which included oatmeal, vegetables, meats, and condensed milk.

Figure 14-2: B vitamins function as coenzymes in metabolism.

The ship with traditional stores returned with some two-thirds of its men either ill or dead of beriberi. The other ship had only four cases. And after intensive interviews, Takaki learned that these four men had not eaten the unusual and unappetizing British meals, but had secretly lived on their rice.

It wasn’t easy to persuade Japanese sailors to eat Western meals. But word of the results spread fast, and the will to survive was persuasive. In 1884, the first year of Takaki’s experiments, 718 out of 5,638 navy men were taken by beriberi. In 1885, the number of sailors grew to 6,918, with only 41 lost. In 1886, the number of deaths from beriberi fell to three, and reached zero in 1887.³

In 1926, thiamin was isolated from rice polishings and pinpointed as the missing nutrient in beriberi.

Thiamin’s Antivitamin

Some foods contain substances which actually destroy vitamins, or interfere with their use. These substances are known as antivitamins. And in some rare instances, these antivitamins can actually produce deficiencies. For this to happen, usually one must either take in very large quantities of the antivitamin, or very small quantities of the vitamin which it can destroy, or there must be some mixture of these two circumstances.

Thiaminase is thiamin’s antivitamin, an enzyme that breaks apart thiamin. It’s found in certain raw fishes, such as carp or herring, and also in a few shellfish, particularly clams and shrimp. The heat of cooking destroys thiaminase. So the fish must be eaten raw and, ordinarily, must be eaten in large quantity (comprising something like a fifth of the total diet) before thiaminase can do much damage.

One can’t help but wonder if the predilection for raw seafood didn’t have some effect upon the speed and severity with which beriberi took hold among the Japanese sailors. Adding to the force of this speculation is the fact that they apparently got beriberi but not scurvy.

We don’t know what foods were consumed by the Japanese sailors, other than rice. But many foods with vitamin C also have thiamin. So why beriberi without scurvy? We can only speculate.

There was usually some fishing on 19th century naval ships. And fresh, raw fish does have some vitamin C, e.g., 3.5 ounces of Pacific herring has about 3 mg of vitamin C. Eaten in sufficient quantity, it could have been sufficient to prevent scurvy. Herring also contains thiaminase, and perhaps this provided part of the answer.

Teetering on a deficiency of both vitamin C and thiamin, eating enough raw fish may have spared the sailors scurvy but pushed them into beriberi.

The case can’t be proven, but it’s a useful exercise in applied nutrition. It shows that we must always consider the whole diet before making nutritional judgments. And in looking at nutrition in any culture, we must consider habits of food combination and preparation.

Thiamin and Body Chemistry

In our look at the metabolism of the energy-providing nutrients (Chap. 11), we saw that thiamin had a key role as a coenzyme. Without thiamin, our cells have a difficult time taking energy from food. No wonder that beriberi sufferers feel that they have no energy. It isn’t surprising that beriberi means “I cannot.”

Wernicke-Korsakoff Syndrome

Wernicke-Korsakoff syndrome is a degenerative disease of the brain caused by a severe thiamin deficiency. In this country, the most common cause is alcoholism. The body requires thiamin as a coenzyme to deal with alcohol metabolism. There’s none in alcohol, so when alcohol supplies much of one’s daily calories, the rest of the diet often can’t furnish the needed thiamin.

The diets of many alcoholics are often severely deficient in thiamin as well as other nutrients, and chronic alcohol consumption impairs the ability to absorb, store, and use thiamin. Not all alcoholics with severe thiamin deficiency develop this disease, probably because of differences in genetic susceptibility.

The disease is characterized by severe mental confusion and memory loss. Also, many victims walk in an unstable and uncoordinated manner, and develop damage to nerves leading to the eyes—causing a tremor of the eyes or causing them to be fixed in a stare. If the disease is caught early enough, many of the symptoms can be reversed with immediate thiamin treatment.

Considering the cost of hospital treatment for these patients and the cost of nursing-home care for those permanently impaired by this disease, fortifying alcoholic beverages with thiamin as a means of prevention would be cost-effective.

Some Fanciful Claims for Thiamin

Reports of beriberi and its cure are perhaps the oldest sources of the popular idea that vitamins confer extra energy. Again, it must be said that a surplus of a nutrient won’t provide extraordinary capacities for whatever is inhibited by the nutrient deficiency. In this case, extra thiamin won’t provide extra energy. When one understands the role of thiamin coenzymes in energy metabolism, it’s obvious why extra doses are pointless—just as extra sparkplugs won’t make an automobile engine more powerful.

Thiamin is generously incorporated into “tonics” as “energy boosters.” It’s used in vain to better athletic performance. The fact that nerve and muscle impairments result from thiamin insufficiency leads to claims that extra thiamin will strengthen weak muscles for the jogger and relieve pains of rheumatism and migraine headaches. Unfortunately, there’s no scientific basis for these beliefs.