Beta Carotene Cannot Substitute For Real Vitamin A (Retinol)
The National Academy of Sciences says that Vitamin A exhibits toxicity for a few people at the Lowest Observed Adverse Effect Level of 21,600 IU when taken for long periods of time, so some dietary supplement companies are substituting beta carotene for Vitamin A in their formulas to avoid the possibility of toxicity. This is a scientific mistake and could cause serious health problems as a result of vitamin A deficiency. This is especially critical for pregnant women, because vitamin A deficiency is associated with several critical problems in child-birth.

Beta carotene converts in the body into retinol. However, while it is commonly assumed that the body can convert beta carotene into real retinol Vitamin A "as needed," efficient conversion does not happen adequately for over half the population.

Additionally, the conversion of beta carotene into the retinol form of Vitamin A in the body is not efficient.

While beta carotene had previously been thought to convert at a rate of about 6 to 1 into retinol in the body, current science calculates the conversion to be as little as 29 to 1. (1,2,3,4)

This means that instead of 12,000 IU of beta carotene converting into 2,000 IU of real retinol vitamin A in the body, it would only convert into about 413 IU, far too little to support health.

Since the Daily Value for Vitamin A (retinol) is 5,000 IU per day for women and men, it would take about 145,000 IU of beta carotene per day to produce an RDA amount of retinol in your body -- if beta carotene conversion happens normally in your body. As was stated above, for many people this is not the case.


Problems arise with Vitamin A deficiency, especially for pregnant women and their babies. Vitamin A deficiency is associated with 74 percent more chance of premature deliveries (5) and with more incidence of Chronic Lung Disease and "a lifetime of breathing abnormalities" in the newborn.(6)

The World Health Organization says that pregnant women should take real retinol Vitamin A and the International Vitamin A Consulting Group, who advises the World Health Organization, says that "It is safe to give all fertile women, independent of their Vitamin A status, as much as 10,000 IU [of retinol vitamin A] daily at any time during pregnancy."(7)

While there is a notion that vitamin A can cause birth defects at 10,000 IU per day because one poorly conducted study by Rothman (8) indicated this, the World Health Organization analysed the Rothman study and dismissed it. They said that all other studies had shown the opposite, "“Recent studies strongly suggest that periconceptional supplements of vitamin A that are close to, but less than 10,000 IU/day, and that are given as a component of a multivitamin, are much more likely to be associated with reduced, rather than increased, risk of malformations.”  This means that optimal vitamin A intake can reduce the amount of birth defects, not increase it. (9)

Vitamin A supplementation can also reduce the potential for the childs' potential for infectious mortality within the first year of birth by 64 percent and incidence of pneumonia, the leading cause of child death, by 50 percent.(10)

Click here to read the fully referenced details in a 18-page review of this subject.

Michael Mooney


  1. Solomons NW. Plant sources of proVitamin A and human nutriture: How much is still too little? Nutrition Reviews 1999 Nov;57(11):350-361.
  2. Tang G, and associates. Vitamin A equivalence of beta-carotene in a woman as determined by a stable isotope reference method.  European Journal of Nutrition 2002 Feb;39(1):7-11.
  3. Brubacher GB, and associates. The Vitamin A activity of beta-carotene. International Journal of Vitamin and Nutrition Research 1985;55(1):5-15.
  4. Hickenbottom SJ. Dual isotope test for assessing beta-carotene cleavage to Vitamin A in humans. European Journal of Nutrition 2002
  5. Radhika MS, and associates. Effects of Vitamin A deficiency during pregnancy on maternal and child health. British Journal of Gynecology 2002 Jun;109(6):689-93.
  6. Hustead VA, and associates. Relationship of vitamin A (retinol) status to lung disease in the preterm infant. Journal of Pediatrics 1984 Oct;105(4):610-5.
  7. International Vitamin A Consultative Group. IVACG statement on safe doses of vitamin A during pregnancy and lactation.
  8. Rothman KJ, et al. Teratogenicity of high Vitamin A intake. N Engl J Med (United States), Nov 23 1995, 333(21):1369-1373.
  9. World Health Organization Micronutrient Initiative. Safe vitamin A dosage during pregnancy and lactation. World Health Organization 1998 WHO/Nut/98.4
  10.  Humphrey J, and associates. Neonatal Vitamin A supplementation: effect on development and growth at 3 years of age. American Journal of Clinical Nutrition 1998;68:109-117.