Vitamin A and Measles: What the data show (and how to talk about it)
RFK Jr. and a new form of germ theory denialism
Last week, Secretary Kennedy appeared on national news, linking the recent measles outbreak to poor nutrition and health and emphasizing the role of vitamin A in preventing measles-related deaths.
Did he pull this out of thin air? Not entirely—there are kernels of truth in his claims. However, as he often does, he left out critical context. And when falsehoods spread from one of the country’s highest health offices, it can have real consequences for families trying to make informed, evidence-based decisions.
So, what do we know about vitamin A and measles? Perhaps more importantly, why do some gravitate toward vitamin A over the MMR vaccine?
TLDR: RFK Jr. has vastly overstated vitamin A’s role in measles in a U.S. context, which can have dramatic consequences. The measles vaccine provides by far the best protection. Regardless, understanding why people believe in falsehoods is crucial—it's the key to making real progress in these conversations.
Vitamin A is helpful for children deficient in vitamin A
When it comes to measles, vitamin A is recommended by the World Health Organization (WHO) for people who contract the disease. But there’s a key reason why.
The WHO serves 197 countries, many of which are low- and middle-income nations where vitamin A deficiency is a major public health issue, particularly among children. In these areas, vitamin A deficiency does make measles far more dangerous because it plays a crucial role in immune dysfunction, particularly in T cell responses and antibody production.
Supplementing among deficient children significantly reduces measles mortality:
A meta-analysis of more than 1 million children across 19 countries found that vitamin A supplementation reduces measles-related mortality by 12%.
An analysis of eight randomized controlled trials found no overall mortality reduction from vitamin A. However, in three studies focused on African children under two years old, vitamin A supplementation reduced mortality by 79%.
However—and this is important—context matters.
The U.S. context: Minimal benefit, real risks
Only 0.3% of the U.S. population has a vitamin A deficiency.
While we don’t have large-scale U.S. data because measles is now quite rare thanks to vaccination, smaller studies from other high-income countries with similarly low levels of vitamin A deficiency suggest vitamin A doesn’t make much of a difference for measles:
A study of hospitalized measles patients in Italy found no effect of vitamin A treatment on outcomes.
A study in Japan found that vitamin A supplementation did not reduce pneumonia risk in measles patients, though it did slightly shorten cough and fever duration.
We also have a case study during a huge Samoa measles outbreak. All patients were given vitamin A, but there were still 89 deaths.
There is some data to suggest vitamin A levels may drop during a measles infection, which is partly why physicians in the U.S. often give vitamin A to children with severe measles requiring hospitalization. When administered in controlled doses under the supervision of a doctor, it is a low-risk intervention, which is why many physicians in Texas are likely giving it to hospitalized measles patients right now and why WHO has a sweeping recommendation. But in the U.S., it’s unclear how much it’s really helping.
Why doesn’t everyone just take vitamin A? Because you can overdose on it.
Home supplementation of vitamin A is risky, especially for children. Since vitamin A is a fat-soluble vitamin, excess amounts can’t be easily excreted and can build up to toxic levels. This can lead to liver damage and other serious health issues.
This risk is compounded by the fact that supplements in the U.S. aren’t well regulated. Unlike prescription medications, vitamin A supplements sold at stores like CVS aren’t tested for consistency or purity by the FDA—meaning the actual dose in each pill can vary.
Vitamin A does not prevent measles
Another danger is that parents might misinterpret this information, thinking vitamin A can prevent measles (it can’t), and give it to their children unnecessarily (which can lead to toxicity).
While vitamin A supplements can reduce mortality in measles cases among deficient children, it does not:
Prevent infection
Prevent long-term complications like hearing loss or subacute sclerosing panencephalitis (a rare but fatal brain disease), which measles can cause
The only intervention that prevents measles, full stop, is the measles vaccine.
Behind the rumor: Why people gravitate to vitamins over vaccination
RFK Jr. ’s embrace of vitamin A and his suggestion that poor diet and exercise are to blame for measles complications are no surprise. His views align with a more subtle form of germ theory denialism, outlined in his recent book, which has gained traction in popular culture.
This perspective doesn’t deny the existence of germs outright but argues that people only become vulnerable to infectious diseases when their immune systems are weakened by poor nutrition or environmental toxins. It follows the same logic as the “comorbidity fallacy”—the idea that Covid-19 deaths weren’t truly caused by the virus but rather by underlying health conditions, poor diet, or lack of exercise.
This belief is particularly tricky because underlying health conditions and poor diet can impact immune functioning. A balanced, nutrient-dense diet is one of the best things you can do to support your health. However, diet alone will never fully protect us from every disease. Immunity is complex, relying on a balance of many factors. Even the healthiest person can die from an infectious disease.
Nevertheless, it has become extremely popular because it:
Gives people a sense of control. The fear of an invisible infectious disease is real and powerful, and exposure to germs is often outside our control. The idea that diet and exercise can serve as a personal shield is deeply comforting.
Allows people to bypass the healthcare system. For those who distrust the healthcare system or can’t access it due to lack of insurance (or both), relying on diet and supplements feels like a way to take charge of their health without needing a doctor’s prescription.
Appeals to our love of nature. There are many wonderful things (and medicines) that come from nature, and “natural living” is a value system that many people hold dear.
To effectively communicate about vitamin A and measles, we must recognize that charts and facts alone won’t change minds. While evidence is essential, people’s gravitation towards natural remedies and supplements is often driven by deeply held values, distrust in healthcare, lack of access to reliable healthcare, and the very human desire for control over our health. The vast majority of people truly want what’s best for their children, and if we just throw more facts at them without understanding their motivations, the conversation won’t get very far.
Bottom line
Vitamin A can help treat measles in children who are deficient in vitamin A, but the benefit for children in the U.S. is far less clear. Vaccination is by far the best way to prevent measles, but when chatting about it, remember that facts alone often don’t change minds—acknowledging and connecting over the values underlying people’s health decisions is a better approach.
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Your Local Epidemiologist (YLE) is founded and operated by Dr. Katelyn Jetelina, MPH PhD—an epidemiologist, wife, and mom of two little girls. Dr. Jetelina is also a senior scientific consultant to a number of non-profit organizations. YLE reaches over 340,000 people in over 132 countries with one goal: “Translate” the ever-evolving public health science so that people will be well-equipped to make evidence-based decisions. This newsletter is free to everyone, thanks to the generous support of fellow YLE community members. To support the effort, subscribe or upgrade below:
Kristen Panthagani, MD, PhD, is a resident physician and Yale Emergency Scholar, completing a combined Emergency Medicine residency and research fellowship focusing on health literacy and communication. In her free time, she is the creator of the medical blog You Can Know Things and author of YLE’s section on Health (Mis)communication. You can subscribe to her newsletter or Substack. Views expressed belong to KP, not her employer.
Katelyn, THANK YOU. This may be one of the most important things you can do - provide clear simple factual information, particularly with kindness and compassion. The kernel of truth in his claims is the dangerous part because it can be presented out of context. I'm enormously grateful for your thorough response!
Love, Daniel
RFK Jr. was a huge part of those 89 measles deaths in Samoa. He's part of the Disinformation Dozen. He's 1 of 12 people responsible for more than 60% of health and vaccine disinformation on the internet and social media. He is a known danger to public health and safety and his willingness to peddle lies is the reson he was nominated in the first place. Being the absolute worst person for the job is now the most important job requirement for anyone in this current administration.