Aluminum is an element abundantly present in the earth. It occurs naturally in food and water and is widely used in products ranging from cans and cookware to medications and cosmetics. Some observational studies suggested a link between brain levels of aluminum and Alzheimer's disease . Since the association was found, many studies have investigated whether aluminum increases the risk for Alzheimer's. The findings are far from clear.
Several meta-analyses examined the association between aluminum levels in drinking water and dementia risk, and the evidence is mixed and inconclusive . The only high-quality study involved almost 4,000 older adults in southwest France (the PAQUID study; ). It found that levels of aluminum consumption in drinking water in excess of 0.1 mg/day were associated with a doubling of dementia risk and a 3-fold increase in Alzheimer's risk . For reference, the 2016 NYC Drinking Water Quality Report (PDF) states that the concentration of aluminum in NYC drinking water ranged from 0.006-0.057 mg/liter (average, 0.02 mg/liter). Of the remaining 13 moderate quality studies, 6 found an association between higher aluminum levels in drinking water and increased dementia risk [7-11], 4 found no associations [12-14], and 1 found a protective effect of higher soil levels of aluminum . Other elements present in drinking water, such as fluoride, copper, zinc, or iron, could also affect cognitive function and the results of these studies .
Some antacids contain high levels of aluminum, as aluminum hydroxide reduces stomach acidity. Among medications, antacids and anti-ulceratives contain the highest levels of aluminum (35-208 mg/dose for antacids and 35-1450 mg/dose for anti-ulceratives) , though aluminum-free options exist (e.g., Rolaids, Tums). A very large meta-analysis of 9 observational studies including more than 6,000 people reported that regular antacid use was not associated with Alzheimer's disease . Even when the analysis was confined to people who used antacids regularly for over 6 months, there was no association with Alzheimer's. Studies with longer follow-up may be needed to definitively exclude the association between antacid use and dementia risk.
Aluminum salts in antiperspirants dissolve into the skin's surface and form a temporary barrier within sweat ducts, which stops the flow of sweat to the skin's surface. No studies have directly examined the link between aluminum-containing antiperspirant use and Alzheimer's risk. However, a few studies have evaluated the link between antiperspirant use and breast cancer. Two studies found no increase in breast cancer risk , but one other study reported that patients who used antiperspirant products more frequently and longer on shaved underarms were diagnosed with breast cancer at an earlier age . Studies show that aluminum salts in antiperspirants are poorly absorbed by the body, and the little that is absorbed is flushed out by the kidneys . However, if you regularly shave with a razor, aluminum may be more readily absorbed via small nicks and abrasions. To limit potential risks, avoid application of antiperspirants shortly after shaving and limit excessive use.
A meta-analysis of 3 observational studies including more than 1,000 people reported that occupational aluminum dust exposure was not associated with Alzheimer's . However, further studies that precisely ascertain aluminum exposure are needed. In a more recent 2016 meta-analysis including 4 studies, the relationship between aluminum exposure and dementia was mixed due to the studies being too small .
There is no consistent or compelling evidence to associate aluminum with Alzheimer's disease. Although a few studies have found associations between aluminum levels and Alzheimer's risk, many others found no such associations. Due to the inconclusive nature of the findings, it may be advisable to limit excessive exposure.
Yuko Hara, PhD, is Director of Aging and Alzheimer's Prevention at the Alzheimer's Drug Discovery Foundation. Dr. Hara was previously an Assistant Professor in Neuroscience at the Icahn School of Medicine at Mount Sinai, where she remains an adjunct faculty member. Her research focused on brain aging, specifically how estrogens and reproductive aging influence the aging brain's synapses and mitochondria. She earned a doctorate in neurology and neuroscience at Weill Graduate School of Medical Sciences of Cornell University and a bachelor's degree in biology from Cornell University, with additional study at Keio University in Japan. Dr. Hara has authored numerous peer-reviewed publications, including articles in PNAS and Journal of Neuroscience.
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