Review of Dietary Advice on Vitamin A
The Scientific Advisory Committee on Nutrition was asked by the Food Standards Agency to reassess dietary advice on vitamin A from both dietary sources, especially liver, and from the, sometimes excessive, use of nutritional supplements.
The main findings of the report (and referenced documents) are:
- The Safe Upper Level for retinol, set by the EVM in 2003, should remain at 1500 ug/day for adults from all sources, food and supplements, on the basis that higher intakes may increase the risk of bone fracture
- Those who consume liver once/week or more should not take any retinol supplements nor should they increase their intake of liver as a 100 g portion of lamb’s liver will typically contain 25,000 ug of retinol, which is equivalent to one month’s typical intake by an adult
- Confirmation of the FSA recommendation that in pregnancy, because of the potential risk of birth defects due to vitamin A excess, no supplements of retinol should be taken except under medical guidance for the treatment or prevention of deficiency
- The National Diet and Nutrition Surveys of adults and the elderly revealed that many (respectively, 6% and 10 %) have intakes in excess of 1500 ug per day and that many (respectively, 12% and 25%) have a mild to moderate excess of vitamin A in the blood (plasma retinol > 2.5 mmol/l)
- High intakes (>1500 ug/day) of retinol are due entirely to the use of nutritional supplements or as a result of consuming liver which, according to the National Diet and Nutrition Surveys provided respectively on average 20% and 30% of intake in adults and 11% and 50% in the free-living elderly. These percentages may have changed since the surveys were conducted
However the report made no mention of:
- the association of elevated blood retinol level with high alcohol consumption
- the impact of liver and renal disease on retinol status
- the fact that animal liver in the UK has approximately three times the retinol content of
that in the US
The committee also did not recommend establish a reporting system for adverse events but did recommend further research on the relationship between retinol intake and fracture risk. Negotiations are taking place between the FSA and the supplements industry as well as the animal feed industry but the problem of excessively high dose supplements and mild to moderate retinol excess continues for many older people. See The Response of the UK Supplement Industry to Safety Issues
See also http://www.food.gov.uk/multimedia/pdfs/reviewvita.pdf
A revised edition of A Review of Vitamin A presented to the Expert Group on Vitamins and Minerals April 2002 which provides much useful additional material on vitamin A toxicity.