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How Vitamin B1 Works


Foods That Contain Vitamin B1
The term "enriched" on food labels means that three B vitamins (thiamin, niacin, and riboflavin) plus one mineral (iron) have been added back to that food to make up for some of the nutrients that were lost during processing. Enriched breads and cereals are, therefore, good sources of thiamin. Pork, oysters, green peas, and lima beans are also good sources. Most other foods contain only very small amounts of thiamin.

A high cooking temperature easily destroys thiamin. As a water-soluble vitamin, thiamin also leaches out of food into cooking water. To preserve the thiamin in foods, cook food over low temperatures in as small an amount of water for the shortest time possible. Steaming and microwaving keep losses to a minimum and often better preserve the natural flavor, too.

Adding baking soda to vegetables to preserve their bright green color destroys their thiamin content.
© 2007 Publications International, Ltd.
Adding baking soda to vegetables to preserve their bright green color
destroys their thiamin content.

To help retain their bright green color, some people add baking soda to vegetables when they cook them. This is not a good idea. Not only does the baking soda make the vegetables lose their shape and consistency, but it destroys the thiamin content. Sulfites, used as preservatives, also destroy thiamin.

Dietary Requirements

The amount of thiamin your body requires depends on the number of calories you eat, particularly the calories you get from carbohydrates. You need 0.5 mg of thiamin for every 1,000 calories (assuming an average intake of carbohydrates). Thiamin intake should be at least 1.0 mg per day even if your total calorie intake is less than 2,000. By increasing your intake of carbohydrates, you also increase your need for thiamin, but your intake of thiamin usually increases, too.

The RDA for thiamin is 1.2 mg for men and 1.1 mg for women until age 50. A pregnant or nursing woman, who needs more calories, requires more thiamin than other women. A varied, well-balanced diet easily supplies the thiamin needed.

This chart lists foods that are good sources of thiamin.

Food Quantity
Thiamin (mg)
Pistachio nuts 1/2 cup
0.54
Watermelon 1 slice 0.39
Filberts or hazelnuts 1/2 cup 0.34
Oatmeal, ready-to-serve 1 cup 0.28
Macaroni, cooked, enriched 1 cup 0.28
Cashews, roasted 1/2 cup 0.28
Peas, green, cooked 1 cup 0.28
Fish 3 ounces 0.27-0.57
Rice, enriched, cooked 1 cup 0.25
Sunflower seeds 1 tablespoon 0.21

Vitamin B1 deficiency causes beriberi, a disease that can be debilitating and even fatal. Keep reading to learn more about vitamin B1 deficiencies.

Thiamin is just one piece of the puzzle when it comes to the nutrients you need for good health. Check out the links below to learn more about these essential vitamins.
  • Vitamin B5, or pantothenic acid, can be found in all living cells and in all foods. Learn about its importance to your diet in How Vitamin B5 Works.
  • Vitamin B6 is actually three substances, pyridoxine, pyridoxamine, and pyridoxal, that work to metabolize protein and amino acids. Read more in How Vitamin B6 Works.
  • In How Biotin Works, learn how biotin acts as a coenzyme in several metabolic reactions, such as the metabolism of fats and carbohydrates.
  • Read How Folate Works to learn about folacin, folic acid, and folate and how a folate deficiency can cause megaloblastic anemia.
  • Vitamin B12, also called cyanocobalamin or cobalamin, is essential because it assists folate in making DNA and RNA. Read more in How Vitamin B12 Works.
  • To learn about the many vitamins in our diet, how much you should be eating, and where to find them, go to our general Vitamins page.
  • If you're looking for the best prices on B vitamins, click here.
This information is solely for informational purposes. IT IS NOT INTENDED TO PROVIDE MEDICAL ADVICE. Neither the Editors of Consumer Guide (R), Publications International, Ltd., the author nor publisher take responsibility for any possible consequences from any treatment, procedure, exercise, dietary modification, action or application of medication which results from reading or following the information contained in this information. The publication of this information does not constitute the practice of medicine, and this information does not replace the advice of your physician or other health care provider. Before undertaking any course of treatment, the reader must seek the advice of their physician or other health care provider.