The first symptoms of thiamine deficiency may be fatigue, instability. These may be followed by confusion, loss of memory, depression, clumsiness, insomnia, gastrointestinal disturbances, abdominal pain, constipation, slow heart rate, and burning
chest pains. As the condition progresses, there may be problems of irregular heart rhythm, prickling sensation in the legs, loss of vibratory sensation, and the muscles may become tender and atrophy. The optic nerve may become inflamed and the vision will be affected.
Generally, with low B1 the central nervous system--the brain and nerves--does not function optimally. The gastrointestinal and cardiovascular systems are also influenced greatly. Vitamin B1 levels have been shown to be low in many elderly people, especially those that experience senility, neuroses, and schizophrenia. We might question how much of the degeneration and disease of old age may be a result of withering digestion and assimilation, leading to deficiencies of various vitamins and other necessary nutrients.
Requirements: The RDA for vitamin B1 is about 1.2 mg. per day, or 1.4 mg. during
pregnancy or lactation. Infants need more per body weight though less in total, about 0.5 mg. per day. Thiamine needs are based on many factors; given good health, we need about 0.5 mg. per 1,000 calories consumed, since B1 is required for energy metabolism. So our needs are based on body weight, calorie consumption, and the amount of vitamin B1 synthesized by intestinal bacteria, which can vary greatly from person to person.
Thiamine needs are also increased with higher stress levels, with fever or diarrhea, and during and after surgery. Those who smoke, drink alcohol, consume caffeine or tannin from coffee or tea, or who are pregnant, lactating, or taking birth control pills all need more thiamine, possibly much more than the RDA, for optimum health.
Thiamine is needed in the diet or in supplements daily. There are some stores in the heart, liver, and kidneys; however, these do not last very long. The minimum B1 intake for those who are very healthy is at least 2 mg. per day. A good insurance level of thiamine is probably 10 mg. a day, though even higher levels may be useful in some situations. When we do not eat optimally, have any abusive substance habits (especially alcohol abuse), or are under stress, increased levels of thiamine are recommended. An example is the B complex 50 products--that is, 50 mg. of B1 along with that amount of most of the other B
vitamins--suggested as a daily regimen. The upper intake levels of thiamine should not be much more than 200-300 mg. daily. Often B1, B2 (riboflavin), and B6 (pyridoxine) are formulated together in equal amounts within a B-complex supplement. When people take higher amounts of the B vitamins, many feel a difference in energy and vitality. (Note: Riboflavin taken for any length of time is best limited to 50 mg. daily.)