To understand what thiamin does in your body, consider the word that describes thiamin deficiency: beriberi. This East Asian word means, literally, "I can’t, I can’t," and people with beriberi can’t do a lot. They’re tired, weak, and uninterested in things, especially food. They may have numb or burning feet, leg cramps, and sometimes mental confusion and an enlarged heart. Recurrent canker sores may also be a tipoff to thiamin deficiency. A study by Israeli researchers found that 70 percent of people with that problem had low blood levels of thiamin, compared to only 4 percent of people who did not have canker sores.
Like the other B vitamins, thiamin is involved in energy metabolism. "That means it helps you to derive energy from the calories you get from food," explains Joanne Curran-Celentano, R.D., Ph.D., associate professor of nutrition and food sciences at the University of New Hampshire in Durham. "It helps to break down the molecules in foods and either rearrange them into a form your body can use for energy or store them for later use as energy."
Thiamin interacts with several enzymes, the biochemical spark plugs that get chemical reactions going in your body. "Several of the enzymes involved in the process of breaking down carbohydrates for energy require thiamin," Dr. Curran-Celentano explains. The fatigue associated with thiamin deficiency is, figuratively, the equivalent of a clogged carburetor. You may have a full tank, but none of the gasoline is being burned to run the engine.
Brain Gain
Thiamin’s ability to make energy available for the body has ramifications for the brain.
"If you dramatically reduce thiamin intake, you reduce the ability of the brain to use glucose (blood sugar). If you reduce that, you have impaired mental function," says Gary Gibson, Ph.D., professor of neuroscience at the Burke Medical Research Institute of Weill Medical College of Cornell University in White Plains, New York. Unlike other body parts, which can switch to other fuels if they need to, the brain uses glucose pretty much exclusively, Dr. Gibson explains.
Thiamin is also very important in the synthesis of critical neurotransmitters in the brain, including one involved in memory and performance—acetylcholine. "We know that thiamin-deficient animals don’t make much acetylcholine and that this lowers their ability to remember and respond," Dr. Gibson says. "So we believe that high levels of acetylcholine are important for proper brain function."
Just how much of a role thiamin plays in human mental performance has yet to be determined. In one study, though, young women with no signs of deficiency who took 50 milligrams of thiamin a day for two months reported feeling more clear-headed, composed, and energetic than those who weren’t getting the supplements. Those taking the extra thiamin also had faster reaction times on tests than those without supplementation.
In other studies, thiamin deficiency has been found to cause mood changes, vague feelings of uneasiness, fear, disorderly thinking, and other signs of mental depression—symptoms that researchers say often affect memory, Dr. Gibson says.
SUPPLEMENTSNAPSHOT
| Thiamin Also known as: Vitamin B1. May help: Beriberi, Wernicke-Korsakoff syndrome, and canker sores. Daily Value: 1.5 milligrams. Special instructions: For best absorption, don’t take with alcohol, tea, or coffee. Who’s at risk for deficiency: Alcoholics, the elderly, strict dieters, and people who are critically ill. Good food sources: Baker’s and brewer’s yeast, lean pork and ham, legumes, nuts, and whole-grain or enriched breads and cereals. Cautions and possible side effects: No known problems from oral doses. |
Thiamin deficiency clearly plays a role in the mental deterioration associated with alcoholism, since alcohol causes thiamin to be excreted faster, and many alcoholics don’t get much of the vitamin because they eat poorly. Some alcoholics develop a condition called Wernicke- Korsakoff syndrome, which is characterized by the inability to form new memories, poorly organized retrieval of old memories, apathy, and emotional blandness.
Thiamin supplementation corrects this condition if it’s caught before permanent nerve damage occurs.
An Alzheimer’s Link?
In some ways, brain problems resulting from thiamin deficiency are similar to those seen with Alzheimer’s disease, Dr. Gibson says. In both cases, he notes, there’s degeneration of the nerves in some areas, and when this occurs, there’s an accumulation of a protein that plays an important role in the development of Alzheimer’s.
The only currently approved Alzheimer’s drug, tacrine (Cognex), works in the cholinergic system, a body-wide system of nerve-cell receptors that are found in the brain, heart, and intestines and that respond to the body’s release of acetylcholine. Thiamin is also needed to make the cholinergic system function.
Thiamin supplementation has been tried in patients with Alzheimer’s, although without much success. Japanese researchers are continuing to study a fat-soluble form of thiamin—one that gets into the brain more easily than regular thiamin—in the treatment of Alzheimer’s disease. "It’s hard to draw any conclusions at this point, or to make recommendations," Dr. Gibson says. "We are simply trying to find out more about thiamin’s basic functions in the brain."
In the United States, thiamin is one of the vitamins found in fortified flour and cereals, so deficiency is not common, Dr. Curran-Celantano says.
The Daily Value is 1.5 milligrams. Men typically get about 1.75 milligrams, and women get 1.05 milligrams. Deficiency is most likely to occur in people who abuse alcohol or who live mostly on empty calories, such as soda and sweets. Others who may develop deficiency-related health problems include older people in nursing homes and hospitals, people who are very ill, and strict dieters.
