Vitamin B1

Vitamin B1, also called thiamine, belongs to the category of water-soluble vitamins (i.e. they dissolve well in water and other aqueous solutions) and is part of group B.

Together with other vitamins of this group, in particular vitamin B2 (riboflavin), B3 (niacin or PP) and B5 (pantothenic acid) and B6 (pyridoxine), it takes part in the metabolism of carbohydrates, fats and proteins, resulting in an essential coenzyme for the reactions that allow the production of energy and for the normal functioning of different organs and systems.

Vitamin B1 also has a key role in supporting neuronal function, both central and peripheral, proving necessary for the correct transmission of nerve stimuli from the brain and spinal cord to the various parts of the body (and vice versa) and for numerous brain functions, such as memorization, concentration.

Sometimes, insomnia can also be caused by a relative deficiency of vitamin B1 and other B vitamins.

In addition, vitamin B1 is essential for the proper functioning of the heart and muscles.

Thiamine, on the other hand, is not directly involved in skin health, for which other B vitamins such as riboflavin, pantothenic acid and niacin are valuable.

Food sources of thiamine

Vitamin B1 is widely distributed in nature and, in general, following a varied and balanced diet for quantity and quality of food consumed, you should not encounter great difficulties in meeting the daily nutritional needs.

However, Western dietary habits can prevent this result due to the prevalent consumption of refined grains and their derivatives, simple sugars, cooked and/or processed foods in various ways at an industrial level.

The most important sources of vitamin B1 are whole grains and products derived from their flours (pasta, rice, bread and bakery products of various kinds, but always wholemeal), wheat germ, brewer’s yeast and pork, followed by sea and freshwater fish (tuna, trout, etc.) and other fish products (mussels, etc.).

Thiamine is also present, albeit in smaller quantities, in some legumes (chickpeas, white beans, Spanish beans), beef liver and meat in general, orange juice, sunflower seeds and yogurt.

On the contrary, milk, as well as eggs, has a fairly low vitamin B1 content, which is further (and substantially) reduced by pasteurization and boiling, while fruits and vegetables are almost devoid of it, especially if they are not consumed raw.

Vitamin B1, like other thermolabile vitamins, fears high temperatures and being water-soluble is dispersed in the cooking water of food, from which it can be recovered only if it is used as a broth (vegetable or meat).

Conversely, thiamine is not affected by freezing: from this point of view, therefore, frozen foods starting from the raw product can be considered nutritionally superimposable to the same fresh products.

For several years now, the vitamin B1 content of many commonly consumed foods has increased thanks to fortification procedures. Among the main foods enriched with vitamin B1 are cereal flours and products derived from them, milk, yogurt, rice, bread, breakfast cereals, as well as some fruit juices.

In cases where it is not possible to ensure an adequate supply of thiamine through food, for example due to increased needs or health problems that prevent adequate nutrition, it is possible to resort to multivitamin and mineral supplements or only B vitamins or thiamine alone.

Vitamin B1 metabolism

After being ingested with food or through food supplements, vitamin B1 is rapidly absorbed in the small intestine, transformed into free thiamine by removal of the phosphate group, introduced into the blood and distributed to the various organs and systems.

The main storage site of thiamine is the liver, which however contains very limited quantities and insufficient to meet the needs in the absence of a constant dietary intake at adequate levels.

Some bacteria present in the endogenous intestinal microflora are able to produce vitamin B1, but it is not known whether this source affects daily nutritional intake and to what extent.

Vitamin B1 is intensively used by the body, especially during periods of considerable physical and intellectual effort, when the diet is rich in carbohydrates, in case of high consumption of alcoholic beverages and if you are heavy smokers.

It is eliminated through the kidneys in the urine like other water-soluble vitamins (for example, vitamin C), and is poorly accumulated.

The elimination of vitamin B1 can be favored by the intake of certain drugs: a phenomenon that should be taken into account in case of prolonged therapies and possibly to be compensated with targeted supplements to avoid encountering more or less significant and harmful deficits.

Among the medicines known to alter the metabolism of thiamine should be remembered some diuretics, used in those suffering from hypertension or heart failure, and some chemotherapeutic agents.

On the contrary, the intake of vitamin B1, even at high doses, has never given rise to significant interactions with pharmacological therapies taken simultaneously, thus making it possible and safe to supplement thiamine possibly necessary even in people suffering from acute or chronic diseases.

How much thiamine does the body need?

Vitamin B1 is essential at all stages of life to support energy metabolism, nerve, cardiac and muscle function.

During fetal life and in the first 6 months of life, the baby’s vitamin B1 needs are met by maternal supply: during pregnancy, through maternal-fetal blood circulation; in the neonatal period, through breastfeeding (or balanced milk formulas, containing all the essential macro and micronutrients).

According to the recommendations of the Italian Society of Human Nutrition (SINU) the recommended intake levels of thiamine correspond to:

• 0.3 mg daily between month 6 and 12
• 0.4 mg/day in children between 1 and 3 years
• 0.5 mg/day between 4 and 6 years
• 0.8 mg/day between 7 and 10 years

Up to this point, the recommended intake levels for vitamin B1 are the same for males and females.

After puberty, however, although further increasing in both sexes,the requirement becomes slightly higher in males than in females, i.e. respectively 1.1 mg/day vs 1.0 mg/day between 11 and 14 years and 1.2 mg/day vs 1.1 mg/day from 15 years onwards. The only exception concerns the period of pregnancy, since the nutritional needs of the fetus raise the woman’s thiamine requirement to 1.4 mg per day.

Some of the circumstances in which the dietary intake of thiamine may be insufficient and worthy of targeted supplementation are pregnancy and lactation and periods of intense physical exercise, especially when associated with a diet rich in carbohydrates, since vitamin B1 is used in metabolic reactions that transform glucose into energy.

Deficiency

In addition to insufficient dietary intake, vitamin B1 deficiency conditions can result from a reduction in intestinal absorption or an increase in its loss in the urine.

The first possibility may be related to a syndrome of intestinal malabsorption, diarrhea, the intake of drugs that alter intestinal transit and the balance of endogenous microflora (laxatives, antibiotics, etc.), alcohol abuse, the outcome of intestinal resections or bariatric surgery for the treatment of severe obesity or the presence of diseases such as HIV/AIDS and hyperthyroidism.

The increased urinary excretion, on the other hand, is mostly due to the aforementioned intake of diuretic drugs.

Among the symptoms that may indicate an initial vitamin B1 deficiency are loss of appetite, fatigue and difficulty concentrating and memorizing.

If the deficiency is significant enough, nausea and vomiting, generalized muscle weakness, mental confusion, impaired intellectual performance and cardiovascular changes (in particular, dilated cardiomyopathy) may occur.

Severe thiamine deficiency today is extremely rare in Western countries and, more generally, in contexts characterized by acceptable nutritional standards. However, the disease that typically occurs in cases of largely insufficient intake, beriberi, can occasionally affect chronic alcoholics, especially in cases where alcohol intake largely replaces the introduction of food.

Beriberi involves striking symptoms, first of all physical wasting (resulting from the impossibility of eating properly and using glucose to produce energy and support muscle work) and alterations of various types affecting the nervous system, with the onset of peripheral neuropathy, impaired sensitivity, possibilities of movement and reflexes, irritability, nervousness and serious impairment of mental functions (further aggravated by toxic effects of alcohol in alcoholics) .

In the most severe cases and not managed promptly, beriberi can cause conditions of severe heart failure and have lethal outcomes. However, if countered in time through high-dose vitamin B1 supplementation, thiamine deficiency and its organic manifestations can be completely reversed, restoring a condition of well-being.

Overdosage

To date, there have never been reports of adverse reactions caused by acute or chronic intake of excessive amounts of vitamin B1. For this reason, the health institutions that define the nutritional standards of the population have not identified an upper limit of safe dosage for this vitamin.

In all likelihood, the fact that vitamin B1 intoxication is a remote event depends on the brief persistence of this compound in the body after ingestion and its rapid elimination through the urine. Nevertheless, it is always good to avoid taking vitamins and minerals in quantities higher than those that the body needs to work well and stay healthy.