Common Signs of Vitamin B1 Deficiency – Dr. Joseph Mercola

Thiamine (vitamin B1) is used by nearly all your cells and is essential for several functions in the body. Thiamine is considered an “essential” vitamin because your body can’t produce it on its own; it must be obtained from outside sources; be it diet or supplementation.

Health Benefits of Thiamine

Thiamine’s key health benefits and mechanisms of action include:

Energy production — Thiamine plays a central role in metabolizing glucose to produce energy for the body. It is essential for the proper functioning of the Krebs cycle, a critical energy-producing pathway that converts proteins, fats, and carbohydrates into energy.

Nerve function — Thiamine is sometimes referred to as an “antistress” vitamin for its positive influence on your central nervous system. It aids in the maintenance of healthy nerve cells and supports the proper functioning of your nervous system. Thiamine deficiency has been implicated in amyotrophic lateral sclerosis (ALS), with ALS patients having about 60% lower thiamine levels in their brains and peripheral nervous systems, resulting in severely impaired glucose metabolism.1 There’s also limited evidence suggesting high doses of thiamine and biotin can help reverse the pathology seen in Huntington’s disease, again by restoring glucose metabolism.2

Heart health — Thiamine contributes to the correct functioning of the heart. It is involved in the production of the neurotransmitter acetylcholine, which is used to relay messages between the nerves and muscles and is essential for normal heart function.

Cognitive function — Adequate levels of thiamine are associated with improved cognitive function. It helps in maintaining a healthy brain, particularly in older adults, and can help prevent disorders related to cognitive decline, including Alzheimer’s.3,4 As explained by the Alzheimer’s Association,5 “Thiamine helps brain cells produce energy from sugar. When levels fall too low, brain cells cannot generate enough energy to function properly.” Indeed, impaired glucose metabolism is a known hallmark of Alzheimer’s and other dementias, and researchers have postulated that this reduction in glucose metabolism is caused by a “decline in thiamine-dependent processes.”6

Digestive health — Thiamine assists in the production of hydrochloric acid, which is essential for proper digestion. Adequate thiamine levels ensure efficient digestion of food and absorption of nutrients.

Prevention of diabetes complications — Research suggests thiamine can help prevent complications in people with diabetes by protecting against oxidative stress and possibly improving glucose tolerance.

Immune function — Thiamine is also important for healthy immune function. In addition to nutrients such as zinc and vitamins C and D, it helps protect against infectious respiratory illnesses. Thiamine deficiency syndrome (beriberi) has also been implicated in other types of severe infections and bears many similarities to sepsis. This is one of the reasons why thiamine is such an important part of Dr. Paul Marik’s sepsis treatment.7 Sepsis, in turn, is a major contributor in influenza deaths in general, and a primary cause for COVID-19 deaths specifically.

Thiamine in Alcohol Addiction and Autoimmune Conditions

Thiamine is frequently recommended and given to people struggling with alcohol addiction, as alcohol consumption reduces absorption of the vitamin in your gastrointestinal tract. An estimated 80% of alcoholics are deficient in thiamine and therefore more prone to the side effects and conditions listed above.⁸

Thiamine is also very important for those with autoimmune diseases such as inflammatory bowel disease (IBD) and Hashimoto’s (a thyroid autoimmune disorder).⁹ In case studies,^10,11 thiamine supplementation has been shown to improve fatigue in autoimmune patients in just a few days.

Interestingly, in one of these studies,¹² which looked at patients with IBD, patients responded favorably to supplementation even though they all had “normal” baseline levels.

The authors speculate that thiamine deficiency symptoms in such cases may be related to enzymatic defects or dysfunction of the thiamine transport mechanism (opposed to being an absorption problem), which can be overcome by giving large quantities of thiamine.

Thiamine Deficiency May Be Underestimated

While thiamine deficiency is often the result of alcohol misuse, chronic infections, poor nutrition and/or malabsorption, research suggests vitamin B1 availability has dramatically declined throughout the food chain in recent years,¹³ and that naturally affects your ability to get sufficient thiamine from your diet.

Adult men and women need 1.2 and 1.1 mg respectively each day.¹⁴ If you have symptoms of thiamine deficiency, you may need higher doses.

Considering both plants and wildlife are becoming increasingly thiamine-deficient,¹⁵ it’s logical to suspect that this deficiency is becoming more common in the human population as well. Unfortunately, statistics on thiamine deficiency in the U.S. population are not readily available in a direct, comprehensive format, so it’s hard to assess how widespread it might be.

Considering how crucial thiamine is for health and optimal biological functioning — and the rapid increase in conditions associated with thiamine deficiency — it’s important to evaluate your intake on an individual level. One way to do that would be to use an online nutritional calculator such as Cronometer. Another way to assess your status is by looking for signs and symptoms of deficiency.

Signs and Symptoms of Thiamine Deficiency

Early symptoms of thiamine deficiency include:^16,17

Fatigue/getting easily exhausted, due to its role in glucose metabolism and energy production

Muscle weakness, as thiamine is required for proper contraction and relaxation of muscles

Poor appetite and/or digestive problems, due to its impact on your digestive function

Brain fog, confusion and/or memory problems, as thiamine is essential for healthy brain function and cognition

Mood swings and irritability

Eye-related issues such as sensitivity to light, eye fatigue and involuntary eye movements

Nutrient malabsorption, as thiamine is involved in the absorption of other nutrients

As your deficiency grows more severe, it can progress into one of four types of beriberi:¹⁸

• Paralytic or nervous beriberi (aka “dry beriberi”) — Damage or dysfunction of one or more nerves in your nervous system, resulting in numbness, tingling and/or exaggerated reflexes
• Cardiac (“wet”) beriberi — Neurological and cardiovascular issues, including racing heart rate, enlarged heart, edema, breathing problems and heart failure
• Gastrointestinal beriberi — Nausea, vomiting, abdominal pain and lactic acidosis
• Cerebral beriberi — Wernicke’s encephalopathy, cerebellar dysfunction causing abnormal eye movements, ataxia (lack of muscle coordination) and cognitive impairments. If left untreated, it can progress to Korsakoff’s psychosis, a chronic brain disorder that presents as amnesia, confusion, short-term memory loss, confabulation (fabricated or misinterpreted memories) and in severe cases, seizures

Are You Getting Enough B Vitamins?

If you have any of the signs listed above or discovered that your daily intake is insufficient using Cronometer, the solution is to eat more foods high in thiamine, such as wheatgerm and acorn squash, and/or take a supplement.

Evidence suggests thiamine insufficiency or deficiency can develop in as little as two weeks, as its half-life in your body is only nine to 18 days.¹⁹ Ideally, select a high-quality food-based supplement that contains a broad spectrum of B vitamins to avoid creating an imbalance. The following guidelines can also help protect or improve your thiamine status:

• Eat fermented foods — The entire B group vitamin series is produced within your gut provided you have a healthy gut microbiome. Eating real food, ideally organic, along with fermented foods will provide your microbiome with important fiber and beneficial bacteria to help optimize your internal vitamin B production as well.
• Avoid excessive alcohol consumption, as alcohol inhibits thiamine absorption, and frequent use of diuretics, as they will cause thiamine-loss.
• Avoid sulfite-rich foods and beverages such as nonorganic processed meats, wine and lager, as sulfites have antithiamine effects.
• Correct any suspected magnesium insufficiency or deficiency, as magnesium is required as a cofactor in the conversion of thiamine.

Daily Intake Recommendations

While individual requirements can vary widely, the typical daily intake recommendations for B vitamins are as follows:

Nutrient	Supplement Recommendations
Thiamine (B1)	Adult men and women need 1.2 and 1.1 mg respectively each day.20 If you have symptoms of thiamine deficiency, you may need higher doses. Thiamine is water-soluble and nontoxic, even at very high doses, so you’re unlikely to do harm. Doses between 3 grams and 8 grams per day have been used in the treatment of Alzheimer’s without ill effect.
Riboflavin (B2)	Suggested daily intake is about 1.1 mg for women and 1.3 mg for men.21
Niacin (B3)	The dietary reference intake established by the Food and Nutrition Board ranges from 14 to 18 mg per day for adults. Higher amounts are recommended depending on your condition. For a list of recommended dosages, see the Mayo Clinic’s website.22 I recommend taking 50 mg of niacinamide, a form of B3 that plays a crucial role in energy metabolism, three times a day. Niacinamide is also a precursor to NAD+, which is essential in the conversion of food to energy, maintaining DNA integrity and ensuring proper cell function.
Vitamin B6	Nutritional yeast (not to be confused with Brewer’s yeast or other active yeasts) is an excellent source of B vitamins, especially B6.23 One serving (2 tablespoons) contains nearly 10 mg of vitamin B6, and the daily recommended intake is only 1.3 mg.24
Inositol/Biotin (B8)	B8 is not recognized as an essential nutrient and no recommended daily intake has been set. That said, it’s believed you need about 30 mcg per day.25 Vitamin B8 is sometimes listed as biotin on supplements. Brewer’s yeast is a natural supplemental source.26
Folate (B9)	Folic acid is a synthetic type of B vitamin used in supplements; folate is the natural form found in foods. (Think: Folate comes from foliage, edible leafy plants.) For folic acid to be of use, it must first be activated into its biologically active form (L-5-MTHF). This is the form able to cross the blood-brain barrier to give you the brain benefits noted. Nearly half the population has difficulty converting folic acid into the bioactive form due to a genetic reduction in enzyme activity. For this reason, if you take a B-vitamin supplement, make sure it contains natural folate rather than synthetic folic acid. Nutritional yeast is an excellent source.27 Adults need about 400 mcg of folate per day.28
Vitamin B12	Nutritional yeast seasoning is also high in B12 and is highly recommended for vegetarians and vegans. One serving (2 tablespoons) provides about 67 mcg of natural vitamin B12.29 Sublingual (under-the-tongue) fine mist spray or vitamin B12 injections are also effective, as they allow the large B12 molecule to be absorbed directly into your bloodstream.