by Gertrud U. Rey
The number of measles cases is steadily increasing across the United States, especially in areas with low vaccination rates. Instead of recommending that children be vaccinated with the measles, mumps, and rubella (MMR) vaccine, US Health and Human Services Secretary Robert F. Kennedy Jr. continues to promote ideas that are rooted in alternative medicine, including the use of vitamin A and cod liver oil to prevent and treat measles. Is there any merit to this recommendation?
Like many of RFK Jr’s health claims, this particular advice is based on a small element of truth, which is why there is so much confusion as to the extent of its usefulness. There is a connection between vitamin A and measles – the question is whether, and in which context, it is clinically meaningful.
Children who are malnourished and have a vitamin A deficiency are at much higher risk of developing severe disease or dying from measles than well-nourished children. Even a healthy child who becomes infected with measles virus can experience a rapid decline in vitamin A levels to below those observed in malnourished children without measles. These observations have inspired multiple randomized, blinded, and placebo-controlled clinical trials, which evaluated the effect of vitamin A treatment in malnourished, vitamin A-deficient children with measles. In each of these trials, children in the experimental group received a high dose of vitamin A on two consecutive days, and the results suggested that recipients of vitamin A were twice as likely to survive as recipients of the placebo control. However, this difference was only statistically significant in children under two years of age.
Based on these findings, the World Health Organization recommends that measles-infected individuals receive one fixed oral dose of vitamin A per day for two days, under the supervision of a doctor. Notably, this recommendation is only valid as a therapeutic treatment in individuals who already have measles, and not as a prophylactic measure to prevent measles. There is no evidence that vitamin A can prevent measles when taken at any dose, in any form, or for any length of time.
Cod liver oil is rich in vitamin A, and is thus often used as a supplementary source of vitamin A. However, non-prescription dietary and vitamin supplements are not regulated by the Food and Drug Administration, so there is no way to ensure that a vitamin A pill or specific liquid volume of cod liver oil actually contains the exact amount of vitamin A claimed on the bottle label. This ambiguity, combined with a general lack of knowledge of how much vitamin A an average person needs, makes it easy for a person to overdose. Unlike other vitamins, which are eliminated in the urine if consumed to excess, vitamin A is fat-soluble and concentrates in the liver. Therefore, long-term and unsupervised high-dose consumption of vitamin A or cod liver oil can lead to vitamin A toxicity, a very serious condition that can cause changes in skin, hair, and vision; and bone problems, seizures, and ultimately, liver failure.
In recent weeks, several unvaccinated children in Texas who were hospitalized for severe measles showed signs of liver damage after undergoing routine lab work. Further inquiry led to the discovery that each of these children had been given high doses of vitamin A with the intent to prevent measles – a strategy that was clearly ineffective in addition to being dangerous. The children are currently undergoing treatment for both the vitamin A toxicity and measles; however, it is difficult to predict the long-term effects of either condition.
Measles is a major cause of childhood morbidity and mortality, and its danger should not be underestimated. Even when measles doesn’t kill, measles encephalitis and pneumonia can cause permanent injury and erase all previous immune memory, putting the person at risk of getting other serious diseases. There is no scientific evidence that any dose of vitamin A or cod liver oil prevents measles, particularly in well-nourished children with normal levels of vitamin A. The only thing that prevents measles is the MMR vaccine, and the evidence that it does so safely and effectively is overwhelming and conclusive.