Kennedy said that while there have been lots of animal studies on food allergies, there has been a dearth of human studies, including research that looks at whether allergies are caused by aluminum-containing vaccines.

"It's pretty easy to figure this out, and we will figure it out," Kennedy said at the Washington event held by the Food Allergy Fund.

A number of vaccines contain aluminum salts as adjuvants, or ingredients that help trigger a stronger immune response.

The Centers for Disease Control and Prevention says on its website that aluminum salts "have been used safely in vaccines for more than 70 years," although it notes that a study from CDC researchers and other scientists in 2022 found a possible link between exposure to aluminum from vaccines and the development of asthma.

A study based on surveys from mothers of homeschooled children, published in 2017, found that vaccinated children were more likely to have allergies than unvaccinated children.

President Donald Trump said in September that the government was removing aluminum from vaccines. No official steps have been taken, but the panel that advises the CDC on vaccines recently said it would analyze the safety of vaccine ingredients such as aluminum, and plans to discuss in a December meeting "adjuvants and contaminants."

Some experts believe the rise in allergies to peanuts and other substances over the years stems from avoidance of those substances. The American Academy of Pediatrics in 2000 said parents should not expose children to peanuts until they turn 3 years old. Peanut allergies have dropped since those recommendations were reversed, a recent study found.

Kennedy said he does not think the spike in food allergies is due to avoidance, citing that his own home was filled with peanut products, yet five of his children still developed allergies, and that countries where peanut butter was introduced did not see large increases in peanut allergies.