Expert Nutrition

(Vitamin B2)

Riboflavin also known as vitamin B2 has an essential role in the metabolism of carbohydrates, fats and proteins, and in the maintaining of healthy mucous membranes (such as the lining of the mouth). After absorption into the body riboflavin must be converted through the addition of phosphate into its active form. Once activated riboflavin is then one of two important coenzymes which work as oxidising agents to power every metabolising cell within the body.

A deficiency in riboflavin does present with some clinical symptoms, however it is not believed to cause any specific diseases and is normally seen with and can often contribute to other B vitamin deficiency disorders, in particular niacin deficiency.

Riboflavin is present in most foods although the best sources include vegemite, milk, dairy products, eggs, liver, kidney and fortified breakfast cereals. Riboflavin is susceptible to destruction in the presence of UV rays from the sun and therefore if foods containing riboflavin such as dairy products are exposed to UV light then the content of riboflavin can be significantly reduced.

Why do vitamin supplements make my urine bright yellow?

If you were to over consume riboflavin, there is a very low chance it will cause toxicity. Research suggests that the intestines cannot absorb any more than about 25mg in a single dose. Additionally as a water soluble vitamin any excess is usually excreted in our urine. It is the excess riboflavin that is responsible for the bright yellow colour that is usually noted by people who take a vitamin supplement.

A recent re-evaluation of dietary requirements for all vitamins and minerals was published by the National Health and Medical Research Council. The dietary recommendations for Riboflavin from this publication are summarised below

Recommended Dietary Intakes for Riboflavin

Please refer to the following definitions when interpreting these recommendations:

RDI-Recommended Daily Intake
The average daily intake level that is sufficient to meet the nutritional requirements of nearly all (97-98%) health individuals in a particular life stage and gender group.

AI-Adequate Intake (used when an RDI cannot be determined)
The average daily nutrient intake level based on observed or experimentally-determined approximations or estimates of nutrient intake by a group (or groups) of apparently healthy people that are assumed to be adequate.

UL-Upper Limit of Intake
The highest average daily nutrient intake level likely to pose no adverse health effects to almost all individuals in the general population. As intake increases above the UL, the potential risk of adverse effects increases.


0-6 months0.3 mg/day
7-12 months 0.4 mg/day

Children and AdolescentsRDI
1-3 years 0.5 mg/day
4-8 years 0.6 mg/day

9-13 years 0.9 mg/day
14-18 years 1.2 mg/day

9-13 years 0.9 mg/day
14-18 years 1.1 mg/day

19-30 years 1.2 mg/day
31-50 years 1.2 mg/day
51-70 years 1.2 mg/day
>70 years 1.2 mg/day

19-30 years 1.1 mg/day
31-50 years 1.1 mg/day
51-70 years 1.1 mg/day
>70 years 1.1 mg/day

14-18 years 1.4 mg/day
19-30 years 1.4 mg/day
31-50 years 1.4 mg/day

14-18 years 1.4 mg/day
19-30 years 1.4 mg/day
31-50 years 1.4 mg/day

The upper level of intake cannot be estimated. There are no adverse events that have been associated with riboflavin consumption as food or supplements and as such the safe upper level of intake cannot be set.

Source: National Health and Medical Research Council. Nutrient Reference Values for Australia and New Zealand. Department of Health and Ageing, Canberra 2006, copyright Commonwealth of Australia reproduced by permission.

Riboflavin back to Vitamins

1. Stanton R. Foods that harm, foods that heal: An A-Z guide to safe and healthy eating. Readers Digest; 2006, pp378-382.
2. The Merck Manual of Medical Information 2nd Ed. Beers, M.H., Fletcher, A. J., Jones T. J., Porter, R., Berkwits, M., et al., editors. Pocket Books Reference; 2003
3. Wahlqvist, M.L., et al. Australia and New Zealand: Food and Nutrition. 2nd Ed. Allen and Unwin, Sydney; 2002, pp 252-254
4. Mann, J., Truswell, S. Essentials of Human Nutrition. Oxford Medical Publications, New York. 2000; pp 200-201.
5. National Health and Medical Research Council. Nutrient Reference Values for Australia and New Zealand. Australian Department of Health and Ageing; 2006 pp 73-78.

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