Vitamin B1 is also known as thiamin or thiamine – the ‘e’ was officially dropped when it was realised that vitamin B1 was not an amine as originally thought. Vitamin B1 offers many health benefits and, as it is water-soluble, is readily lost via the kidneys. A regular dietary supply of vitamin B1 is therefore essential. Low vitamin B1 intakes can lead to deficiency symptoms within as little as one month.
Vitamin B1 Benefits
Vitamin B1 plays a central role in metabolism as it is needed for the production of energy from glucose. Without vitamin B1, an enzyme called pyruvate dehydrogenase cannot process a substance called pyruvate which is formed when glucose is broken down to release energy (glycolysis). In general, the more carbohydrate you eat, the more thiamin you need.
Vitamin B1 is also involved in the synthesis of some amino acids, and for the secretion of insulin hormone from pancreatic beta-cells. Vitamin B1 is also needed for nerve cell stimulation and mood regulation.
Within the EU, the European Food Safety Authority has authorised health claims that vitamin B1 contributes to:
- Normal energy-yielding metabolism
- Normal functioning of the nervous system
- Normal psychological function
- Normal function of the heart.
Food Sources of Vitamin B1
Thiamin is obtained from:
- Unrefined wholegrains, especially oatmeal
- Meats – especially pork which provides around 1mg thiamin per 100g
- Fruit, nuts and vegetables
- Dairy products
- Pulses and soy flour
- Yeast extract
Thiamin is readily lost during food processing. If sulphur dioxide is added to meat mince to preserve its colour, the meat will lose 90% of its thiamin content within two days. Similarly, sulphites added to processed potatoes to maintain their whiteness quickly lose half their thiamin content.
During baking and toasting, bread loses a third of its vitamin B1, and if baking powder is added, losses increase to 50%.
Foods that are boiled also lose half their thiamin content into the water. Roasting meat at 200 degrees C reduces its vitamin B1 content by 20%, while freezing meat reduces its B1 content by up to 50%.
Vitamin B1 deficiency
Lack of vitamin B1 interferes with cell metabolism so that glucose is not processed properly. This causes lactic acid to build up in a similar way to when cells do not receive sufficient oxygen. Muscle cells which have a high energy requirement, such as heart muscle cells, are particularly affected by vitamin B1 deficiency.
Thiamin deficiency is common in under-developed countries where polished white rice is a dietary staple rather than brown rice. In some parts of Indonesia, for example, as many as two out of three people are affected by a lack of vitamin B1.
In developed countries, people over the age of 55 are most at risk of thiamin deficiency – partly due to low dietary intakes and partly due to reduced absorption of B vitamins from the intestines.
Thiamin deficiency can also develop as result of taking diuretics so that more vitamin B1 is lost via the kidneys. Other causes of thiamin deficiency include excessive vomiting during pregnancy, stress, which depletes thiamin stores, and high intakes of alcohol, which interfere with thiamin metabolism.
Recently, it was also recognised that thiamin deficiency affects between 15% and 29% of obese people seeking bariatric surgery, as people who are overweight have a greater metabolic need for thiamin. After bariatric surgery, malabsorption can also lead to thiamin deficiency.
Symptoms that may be due to thiamin deficiency include:
- loss of appetite
- loss of concentration
Severe vitamin B1 deficiency leads to a condition known as beriberi, which derives from the Sinhalese term for extreme weakness.
Dry beriberi produces weakness, numbness and pins and needles in the limbs, while wet beri-beri is associated with severe fluid retention.
Symptoms that may be due to major thiamin deficiency include:
- poor memory
- muscle weakness and stiffness
- nerve tingling, burning and numbness
- progressive paralysis
Two forms of brain damage are also recognised as a result of severe vitamin B1 deficiency, Wernicke’s encephalopathy and Korsakoff syndrome.
Vitamin B1 and tiredness
Some older people experiencing fatigue and loss of appetite may have low intakes of vitamin B1 and vitamin B complex supplements can improve general well-being. In one trial, taking 10 mg thiamin per day helped people over the age of 65 to enjoy better quality sleep, increased energy levels and lower blood pressure than those taking a placebo.
Vitamin B1 and mood
Vitamin B1 promotes calmness, clear-headedness, self-confidence and can lift your mood. People with low levels of thiamin are more likely to feel depressed than those with higher levels. A study involving women with low thiamin status and poor mood showed significant improvements after taking thiamin supplements for 3 months. When 120 young women took either 50mg vitamin B1 or placebo every day for 2 months, those taking the vitamin B1 tablets felt significantly more clearheaded, composed and energetic, and had faster reaction times than those taking placebo.
In a recent study involving people who were prescribed antidepressant drugs in hospital, the addition of vitamin B1 to their treatment improved the rate at which they responded to treatment. Improvements in mood were seen within 6 weeks and no adverse side effects were reported.
Vitamin B1 and painful periods
A trial involving 556 teenage girls with painful periods found that taking vitamin B1 (100mg) per day for 3 months fully alleviated symptoms in 87% and improved pain in 8% with only 5% showing no response.
Vitamin B1 and PMS
When 80 students with pre-menstrual syndrome were asked to take either vitamin B1 or placebo, those taking the vitamin B1 supplements showed a 35% reduction in emotional symptoms and a 21% reduction in physical symptoms. The response in those taking vitamin B1 was significantly greater than in the placebo group.
Vitamin B1 and arterial disease
Vitamin B1 appears to have a protective effect against hardening and furring up of the arteries (atherosclerosis), especially in people with type 2 diabetes, and can improve the ability of blood vessels to dilate.
Vitamin B1 and heart failure
Lack of thiamin may be an unrecognised contributor to heart failure, with some studies finding that as many as 91% of people with heart failure being affected.
Vitamin B1 dose
Requirements increase during pregnancy and lactation.
The average diet supplies 1.5 mg vitamin B1 per day.
Thiamin is included in almost all multivitamins and minerals and in high dose Vitamin B Complex supplements.
Doses provided in supplements range from the RDA of 1.1mg up to 100mg.
Vitamin B1 safety
The European Food Safety Authority felt unable to determine a tolerable upper intake level for long-term use from supplements due to lack of data, as excess is rapidly cleared from the body via the kidneys producing a very low risk of adverse effects.
For guidance purposes, the UK Expert Group on Vitamins and Minerals suggested that, based on one study, an upper tolerable level of 100 mg/day of supplemental thiamin would not be expected to cause adverse effects.
Do You Need A Multivitamin? My Quick Nutrition guide (46 pages) is currently free via this link
My Essential Guide to Vitamins, Minerals and Herbal Supplements offers a complete overview of each vitamin, mineral, dietary oils and herbal remedy.
Image credits: ivanna_grigorova/shutterstock