Vitamin B2 is also known as riboflavin. Vitamin B2 is needed to drive energy production in cells and its main benefits relate to overcoming tiredness and fatigue, and preventing migraine and pre-menstrual syndrome.
Vitamin B2 benefits
Vitamin B2 acts as a building block to produce a vital factor (flavin adenine dinucleotide, or FAD) which plays a key role in the metabolism of proteins, fats and carbohydrate. Your cells use vitamin B2 to generate energy in a metabolic pathway known as Krebb’s Cycle, or the Citric Acid Cycle. Riboflavin is also needed for the secretion of insulin hormone from the pancreas, for the production of thyroid hormones, and is also involved in immunity and the production of antibodies and red blood cells. As an antioxidant, it helps to protect against premature ageing, and helps to maintain the integrity of hair, skin, mucous membranes and nails.
Within the EU, the European Food Safety Authority has authorised health claims that riboflavin contributes to:
- Normal energy-yielding metabolism
- Normal functioning of the nervous system
- The maintenance of normal mucous membranes
- The maintenance of normal red blood cells
- The maintenance of normal skin
- The maintenance of normal vision
- The normal metabolism of iron
- The protection of cells from oxidative stress
- The reduction of tiredness and fatigue.
Food Sources of vitamin B2
As riboflavin is essential for all cells to generate energy, it is found in all cell-based animal and plant foods, although only yeast and liver provide more than 2mg per 100g. Sources include:
- yeast extract
- offal (liver, kidney, heart)
- lean meats
- wholegrain cereals
- dairy products
- egg white and fish roe
- green leafy vegetables.
Vitamin B2 is readily lost during cooking, and when boiling or steaming vegetables is responsible for colouring the cooking water yellow. You can reclaim some of this lost riboflavin by using the water to make sauces, gravy and soups.
Vitamin B2 is readily deactivated by both heat and cold. Milk loses 20% of its vitamin B2 content during pasteurisation, for example, and what remains is further reduced by 90% after just two hours of sun exposure – one reason why milk is now mostly sold in cartons rather than bottles. Boiling milk also reduces its vitamin B2 content by up to 25%, while freezing meat halves its vitamin B2 content.
Vitamin B2 deficiency
Severe lack of vitamin B2 (ariboflavinosis) is rare in western countries, but is occasionally diagnosed in vulnerable groups such as the elderly and people with anorexia or alcohol dependency. Worldwide, children in developing countries are most at risk of B2 deficiency.
Because vitamin B2 is needed to secrete insulin in response to rising blood glucose levels, it has been suggested that lack of vitamin B2, or abnormal vitamin B2 metabolism, increases the risk of type 2 diabetes, although this needs further investigation.
Symptoms that may be due to vitamin B2 deficiency:
- tired, sensitive, gritty, blood-shot eyes
- sensitivity to bright light
- mouth ulcers, sores and cracks at the corner of the mouth (angular cheilosis)
- sore throat and tongue
- scaly eczema-like skin rash, especially on the face and nose
Symptoms that may be due to a severe lack of vitamin B2:
- muscle weakness and trembling
- dull, oily hair and hair loss
- split or brittle nails
- poor concentration and memory
- poor glucose tolerance.
Vitamin B2 and migraine
Data from 11 study suggest that taking vitamin B2 supplements can prevent migraine attacks in adults, although they appear to be less effective for children.
In one study, the frequency of migraine attacks and the number of headache days per month was reduced by at least half in around 60% of those taking a supplement providing 400mg riboflavin daily. In those taking placebo, only 15% achieved a similar result.
Vitamin B2 and PMS
A study that followed 1057 women for ten years found those with the highest dietary intakes of vitamin B2 were 35% less likely to develop premenstrual syndrome (PMS) than those with low intakes.
Vitamin B2 is also needed to convert vitamin B6 into its active form, and to support its benefits in PMS. Because of this, riboflavin is often included in nutritional supplements designed to improve the symptoms of pre-menstrual syndrome. It is also helpful for reducing menstruation-associated migraine attacks.
Vitamin B2 and homocysteine
Vitamin B2 helps to lower blood levels of homocysteine – a harmful amino acid that is linked with hardening of the arteries. This action is usually of lesser importance than that of vitamin B6, vitamin B12 and folate, but becomes important in some people who have inherited reduced activity of an enzyme (MTHFR) needed for normal homocysteine metabolism.
Vitamin B2 and pregnancy
Vitamin B2 may provide some protection during early pregnancy against a type of developmental abnormality called a neural tube defect which includes spina bifida and hydrocephalus. Vitamin B2 is usually included in multivitamins designed for pregnancy, along with folic acid and vitamin B12.
Vitamin B2 and cataracts
Vitamin B2 is needed for an antioxidant enzyme in the eye (glutathione reductase) to work properly and protect the lens from oxidation reactions that trigger cataracts. People with good intakes of vitamin B2 are around a third less likely to develop lens opacities that affect vision than those with low intakes.
Vitamin B2 dose
Requirements increase during pregnancy and lactation.
The average diet supplies 2.3mg vitamin B2 per day for men and 1.8 mg per day for women.
In general, people who are physically active need more vitamin B2 than people with a sedentary lifestyle.
The amount of vitamin B2 included in supplements ranges from the RDA of 1.1mg up to 400mg. These higher doses of 100mg and 400mg vitmain B2 were used in clinical trials to treat migraine.
Vitamin B2 safety
High doses of vitamin B2 will colour your urine bright yellow, but this is harmless. Vitamin B2 is one of the safest vitamins to take, and the European Food Safety Authority felt unable to set a tolerable upper intake level for long-term use from supplements due to lack of evidence that any dose was harmful. This is because excess vitamin B2 is rapidly cleared from the body via the kidneys, producing a very low risk of adverse effects.
For guidance purposes only, the UK Expert Group on Vitamins and Minerals suggested that an upper tolerable intake of 40 mg riboflavin/day in addition to food intakes, would be unlikely to result in adverse effects. However, higher doses of up to 400mg per day have been used in clinical trials with no adverse effects. If in doubt, seek advice from your doctor or a pharmacist.
Very high intakes may cause skin itching, numbness and pins and needles.
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