Next up is one of the B vitamins, Vitamin B1, otherwise known as thiamine. All living things need thiamine. However, plants, bacteria and fungi can produce their own. Animals such as ourselves have to obtain it in our diet. Thiamine was the first water-soluble vitamin discovered. It was first recognized in 1884 when a surgeon general in the Japanese Navy Kanehiro Takaki noticed health benefits when a more varied diet was used on Navy ships instead of just the standard white rice predominant diet. This change in diet helped to alleviate many of the nerve and heart problems seen in the sailors. Unfortunately the Japanese navy did not feel it was worth the expense of the more varied diet.
Thiamine and other B vitamins are important for breaking down starch, sugars and carbohydrates to use as energy and also play a key role in nerve signal transmission. These functions make thiamine important for energy levels, the nervous system, muscle health and the digestive system.
Thiamine is found in a wide variety of foods but the highest concentration is in yeast, pork, and beans. The main source of thiamine in the diet is from grains. However, yet another reason to eat whole grains rather than highly processed ones is that thiamine is mostly found in the outer layers and germ of the grains that are removed during processing. In the US thiamine is added back in to processed flour. Thiamine is not stored by the body so symptoms of thiamine deficiency can form after even short periods of not eating enough (in as little as 2 weeks).
The recommended daily allowance for Thiamine is 1.4 mg. However some studies have shown benefits to higher doses up to 50 mg. It is likely the lower limit for ideal health lies somewhere around 5 mg or greater as it has been observed that the bodies absorption of thiamine decreases above this level. There are no adverse effects to excess thiamine as it is a water-soluble vitamin and excess amounts are easily excreted by the body in the urine.
Thiamine deficiency causes two main well know syndromes. The first one is Beriberi. Dry beriberi is a disease mostly of the peripheral nerves (those nerves further down than the spinal cord). This causes what is called a peripheral neuropathy where these nerves are damaged causing numbness, tingling, weakness, difficulties walking, and abnormalities in the reflexes. Wet beriberi has all of these symptoms from peripheral neuropathy but also leads to heart failure as well. It is called wet because the heart failure leads to a back up of fluid into the lungs and lower extremities causing swelling/edema. When treated the heart failure can improve rapidly but peripheral nerves can regenerate themselves (unlike central nerves like those in the spinal cord and brain) but this process takes months to correct.
Thiamine deficiency causes central nerve problems in the brain as well. In developed countries this usually happens in alcoholics as alcohol interferes with thiamine uptake by the body and displaces food in the diet that is normally the source of thiamine. It causes two conditions referred to as Wernicke encephalopathy and Korsakoff syndrome. But they so commonly happen together that they are often referred to as a blanket term Wernicke-Korsakoff syndrome. The Wernicke encephalopathy is a constellation of problems with eye movements, altered mental status, and difficulties walking. Kosackoff is a thiamine deficiency induced severe impairment in memory. Thiamine deficiency can also lead to visual disturbances.
Thiamine is mostly only used in medical practice whenever a person struggling with alcoholism is admitted to the hospital. They are routinely given thiamine to help prevent Wernicke-Korsakoff syndrome. Other than that thiamine is rarely used in medical practice.
Some studies have looked at the role of thiamine in Alzheimer’s disease. This article described some of the results showing that thiamine supplementation does show benefit in the cognition of those with Alzheimer’s disease. As this study showed there is an issue with many of the studies done with thiamine as they will often use doses as low as 3 mg per day which is likely lower than what the average person should be eating a day. The elderly absorb thiamine even less effectively than younger people so treatment doses should likely be well in excess of 10 mg but studies rarely do this. Giving IV is another option but this limits using the results for the general public as outpatients. However, what studies have been done show little or no benefit and studies looking at thiamine levels in the cerebrospinal fluid (CSF) showed no correlation with the level and risk for Alzheimer’s. Therefore it seems unlikely that thiamine will play a major role in the treatment of Alzheimer’s. However supplementation or increased intake in the diet may help a little. (however studies do show that Vitamin A may play a role in the treatment of Alzheimer’s Dementia. Please see my previous post and this study.)
In heart failure some studies have shown that thiamine deficiency may play a role, which is logical given the known syndrome of wet beriberi. However, even in patients with heart failure due to other reasons such as coronary artery disease these patients often receive a diuretic called lasix to help keep fluid levels low in the body. It has been shown that lasix causes increased excretion of thiamine which leads to low levels further worsening heart failure. Finally this was studied in a well designed but disgracefully small study (9 patients). The study showed a 4% improvement in cardiac function (which in heart failure patients is a lot) with thiamine supplementation. There is also a well-known heart failure in alcoholics called alcoholic cardiomyopathy which could easily at least partially be explained by thiamine deficiency yet few of these patients receive thiamine supplementation at home. And then there is a large group of what we call idiopathic cardiomyopathies where patients have heart failure of unknown cause. Despite not being able to find a cause thiamine deficiency is rarely if ever entertained and thiamine is equally rarely given. Given the data I see no reason why every single hear failure patient shouldn’t be given thiamine supplementation. Many of them are on lasix anyway which deplete thiamine and may further worsen their heart failure. And in a small group we may find that thiamine deficiency was the sole cause of their heart failure and they will be cured. The study to look into the effect of thiamine on heart failure would be easy to do with a randomized controlled trial. However, given thiamine’s almost complete lack of risk for toxicity and being very cheap I see no reason not to give all heart failure patients thiamine now with the data we already have.
Early studies are showing too that thiamine may be especially helpful for diabetics especially in preventing damage to peripheral nerves which can cause a condition called diabetic neuropathy, which causes tingling, pain, or numbness in the toes, feet and legs. This article even lays out how thiamine deficiency may play a key role in the damage to blood vessels that lead to heart disease, eye problems and strokes in diabetics.
This placebo controlled trial showed an improvement in energy levels, mental clarity and response times with thiamine supplementation of 50 mg/day. This was in individuals who at baseline had what was considered adequate thiamine intake and levels.
Thiamine and cancer is being actively investigated. It has been shown that thiamine levels are very low in cancer patients. However, this does NOT mean that thiamine deficiency causes or even increases the risk for cancer. It is entirely possible that the thiamine deficiency is caused by the cancer or is actually part of the body’s defense mechanisms against the cancer. One supporting piece of information for this is the observation in one study that cancer growth actually increased at doses a few times higher than the recommended daily allowance. However it has also been shown that thiamine doses thousands of times higher than the RDA dose actually inhibit cancer growth. This is an ongoing area of investigation and will be very interesting to watch going forward. But given the current data giving thiamine to cancer patients without thiamine deficient symptoms would not be advisable as data to date shows no benefit and possible harm.
Overall with the data we have so far the role of thiamine in heart failure and diabetes should be investigated with larger placebo controlled trials. But given its almost complete lack of toxicity and the data we already have so far likely all patients with heart failure and all diabetics should be on a relatively high does of thiamine (about 50 mg) daily.
Thiamine is a prime example of how vitamins can serve as medicine while being far cheaper and safer than modern pharmaceuticals.
Thiamine and Alzheimer’s http://www.ncbi.nlm.nih.gov/pubmed/22218733
CSF thiamine levels and Alzheimer’s http://www.ncbi.nlm.nih.gov/pubmed/12111441
Vitamin A and Alzheimer’s – http://www.ncbi.nlm.nih.gov/pubmed/22221326
Lasix, heart failure and thiamine – http://www.ncbi.nlm.nih.gov/pubmed/1867241
Small but well designed thiamine study – http://www.ncbi.nlm.nih.gov/pubmed/22057652
Article on thiamine and its role in vascular damage in diabetics – http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3376872/