Sensationalist stories about how cooking with aluminum foil will give you Alzheimer’s rely on a number of untested assumptions that sometimes strain credulity.

For decades, scientists have alleged a connection between aluminum and Alzheimer’s disease, and it has been a long-standing debate within the scientific community.

The specific claim of cooking with aluminum foil often pops up in viral news stories, like the one published on clickbait site awm.com (“Doctors Now Have Warning: If You Use Aluminum Foil, Stop It Or Face Deadly Consequences”) which made this argument:

Simply put, if you cook with aluminum foil, you are playing with your health. The first thing you need to know is that aluminum is bad for your brain. It is a neurotoxic heavy metal that has been linked to Alzheimer’s disease for years.

This claim rests on three assertions. First, that cooking with aluminum foil will liberate aluminum and be transferred to your food in a form that can be ingested; second, that this aluminum will reach your brain in concentrations high enough to be significant; and third, that high concentrations of aluminum in your brain put you at increased risk of Alzheimer’s.

Will cooking with aluminum foil liberate aluminum? Yes, acids typically dissolve metals, and aluminum is no exception. A 2012 study published in the International Journal of Electrochemical Science that is often cited in viral news stories because of its more alarmist claims about Alzheimer’s, investigated how much was liberated by cooking food in foil. Not surprisingly, they found that it varied depending on things like temperature and acidity, but that aluminum did, in fact, leach into food:

Aluminum foil used in cooking provides an easy channel for the metal to enter the human body. The increase in cooking temperature causes more leaching. The leaching is also highly dependent on the pH value of the food solution, salt, and spices added to the food solutions.

How much of that leached aluminum would stay in your body? Not much. Most research on the topic agrees that it’s much less than 1%. A 2011 report in the journal Neuroscience stated that “healthy humans and laboratory rats absorb between 0.06% and 0.4% of ingested Al”.

Could that ~0.4% of leached aluminum make it to your brain? Based on studies that directly injected rats with high doses of aluminum, the answer is yes, but not much. According to the World Health Organization, once the aluminum does make it into your bloodstream, a very small percentage (of an already small percentage of ingested aluminum) actually ends up in your brain:

Approximately 60, 25, 10, 3 and 1% of the aluminium body burden is in the bone, lung, muscle, liver and brain, respectively.

Ultimately, the amount of aluminum you would need to eat on a regular basis to get a buildup in the brain is unrealistically large. But, for the sake of argument, let’s say you do get some of that leached aluminum in your brain. Will it increase your risk factor for Alzheimer’s?

The debate about the connection between aluminum and Alzheimer’s has gone on for decades, originally inspiredby the observation that the brains of Alzheimer’s patients had high concentrations of aluminum compounds and that a major symptom of the disease is the buildup of plaque that contains aluminum compounds.

At the moment the field remains mixed on the role of aluminum as a possible risk factor for Alzheimer’s. Both the Alzheimer’s Society of Canada and the international Alzheimer’s Association’s official stance is that aluminum is not a risk factor for the disease. A 2008 CDC toxicology report describes the scientific consensus in this way:

Although a possible association was proposed over 40 years ago, this association is still highly controversial and there is little consensus regarding current evidence. A number of studies have found weak associations between living in areas with elevated aluminum levels in drinking water and an increased risk (or prevalence) of Alzheimer’s disease; other studies have not found significant associations.

In contrast, no significant associations have been found between tea consumption or antacid use and the risk of Alzheimer’s disease; although the levels of aluminum in tea and antacids are very high compared to drinking water, aluminum from these sources is poorly absorbed. The available data do not suggest that aluminum is a causative agent of Alzheimer’s disease; however, it is possible that it may play a role in the disease development.

More recent studies have come to light that may end up re-invigorating the debate, but both the connection to Alzheimer’s and its mechanism for causing the disease are far from settled science. That being said, it’s incredibly unlikely you are exposing your brain to high concentrations of aluminum by cooking with aluminum foil in the first place.