These bottles are typical, claiming they
"support healthy brain function" even with no
clinical proof and the meaningless word "support."

Walk the supplement aisle and you'll find ginkgo biloba sitting right next to the word memory. Sometimes on the same line of the same box. The pairing is deliberate.

Read the label and the bottles say something careful. Ginkgo supports healthy brain function. Under a 1994 law called the Dietary Supplement Health and Education Act, that's a structure and function claim. A company doesn't have to convince the FDA of anything before printing one. It's supposed to hold evidence that the statement is truthful and not misleading, and it has to add the small line about how the FDA hasn't evaluated it. Nobody checks first.

What the company can't print is that ginkgo prevents or treats Alzheimer's disease. That's a disease claim, and that takes proof.

So support does the work. It's a word nobody can measure, which means nobody can prove it wrong.

Researchers went ahead and tried anyway.

The biggest attempt was the Ginkgo Evaluation of Memory study, published in the Journal of the American Medical Association in November 2008. Researchers led by Steven DeKosky recruited 3,069 people aged 75 and older, some with normal memory and some with mild cognitive impairment. Half took 120 milligrams of ginkgo twice a day. Half took a placebo. They were followed for a median of six years.

One detail matters. The tablets weren't drugstore capsules. They were EGb 761, the standardized German extract used in most serious ginkgo research, donated by the company that makes it.

Ginkgo did not lower the rate of dementia or Alzheimer's disease in either group. If anything the numbers leaned the wrong way. There were 277 cases of dementia in the ginkgo group and 246 in the placebo group, a gap too small to mean anything, but not the direction anyone was hoping for.

Four years later a French trial called GuidAge published in Lancet Neurology. It followed 2,854 adults over 70 who had gone to their doctors worried about their memory, using the same extract at the same dose for more than five years. Same answer. Long-term ginkgo didn't reduce the risk of progressing to Alzheimer's.

If you're younger and just want sharper recall, a 2012 meta-analysis in Human Psychopharmacology pooled the trials in healthy adults and found no reliable benefit for memory, attention or executive function.

Memory isn't the only thing on the label. Ginkgo gets promoted for tinnitus, high blood pressure, peripheral artery disease, macular degeneration and altitude sickness. None of those uses has convincing evidence behind it either.

So the pills don't do much. There's also the question of what's in them. A Dutch analysis of 29 commercial products found that 25 fell short of the composition expected of the standardized extracts used in clinical research, and most didn't match their own labels. A 2015 chemical analysis found something worse, with products spiked with cheaper flavonoids to make weak extracts look like they met spec. Those samples are old now, and a third-party seal from USP or NSF is about the only check a shopper has.

Now the part the ads never get to.

The National Toxicology Program ran a two-year animal study and found clear evidence of liver cancer in mice, along with weaker signals for thyroid tumors in rats and mice. In 2016 the International Agency for Research on Cancer classified ginkgo extract as possibly carcinogenic to humans, based mostly on those animal results, while stating that the human evidence is inadequate.

European regulators reviewed the same data and reached a different conclusion, deciding the rodent tumors reflect high-dose mechanisms unlikely to apply to people taking approved doses. Both of those things are true at once, which is roughly where the science sits.

Ginkgo may also increase bleeding risk, particularly alongside anticoagulants or antiplatelet drugs, though the clinical evidence is mixed. European guidance suggests stopping it several days before surgery as a precaution, and anyone on blood thinners should raise it with their doctor.

People with epilepsy are told to be careful, since ginkgo has been linked to breakthrough seizures in case reports. There's no good safety data in pregnancy. And ginkgo seeds are not the same thing as leaf extract. The seeds are genuinely toxic, especially to children.

One fair caveat. Everything above is about preventing memory loss in people who don't have dementia. Treating people who already have it is a separate question with a messier answer, and some trials of high-dose extract have shown modest effects. That's a treatment question for a clinician, not a decision to make from a label.

For everyone else, here's where it lands. Two of the largest prevention trials ever run on ginkgo followed nearly 6,000 older adults for five and six years. Neither prevented dementia. Trials in healthy adults haven't turned up reliable memory gains either. More than a decade later, nothing has overturned that. Save your money.

The bottles haven't changed a word.

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6/26/2016
Updated 9/10/2026