Supplements Studied for Age-Related Memory Decline: Ginkgo and Omega-3

Ginkgo biloba and omega-3 fatty acids are two of the most widely purchased supplements marketed toward memory and cognitive aging, yet the research behind each tells a more complicated story than most product labels suggest. This guide summarizes what the NIH Office of Dietary Supplements and the National Center for Complementary and Integrative Health actually report, so you can have a more informed conversation with your clinician.

Please note that dietary supplements are not intended to diagnose, treat, cure, or prevent any disease, and these statements have not been evaluated by the FDA.

Ginkgo Biloba

What It Is

Ginkgo biloba is a tree native to China. Extracts made from its leaves contain two main groups of plant compounds: flavonoids and terpene lactones. Supplement manufacturers market these compounds for cognitive support and circulation. Ginkgo has a long history of use in traditional practice for circulation-related complaints, though the NIH notes this history does not constitute conclusive modern evidence of benefit.

Is There a Recommended Intake?

According to the NIH Office of Dietary Supplements, no adult target intake and no upper intake limit have been established for ginkgo biloba. There is no Recommended Dietary Allowance, Adequate Intake, or Tolerable Upper Intake Level for this supplement. Always ask a clinician or pharmacist about an appropriate amount for your individual situation.

What the Evidence Shows

The NIH grades the evidence for ginkgo's most commonly claimed uses as follows:

• Preventing dementia or cognitive decline in older adults: Insufficient evidence. This is among the most studied claims, but research has not established a benefit.
• Improving cognitive performance in healthy people: Insufficient evidence. The NIH states that the effect of ginkgo on cognition in healthy people is uncertain.
• Relieving symptoms of existing dementia: Limited evidence. Some studies suggest a possible effect, but the body of research is not strong enough to draw firm conclusions.
• Heart disease, high blood pressure, tinnitus, or multiple sclerosis: Insufficient evidence for each of these uses.
• Anxiety, PMS, schizophrenia, vertigo, or stroke rehabilitation: Insufficient evidence for each of these uses.

Safety and Side Effects

Ginkgo leaf extract is considered likely safe for most adults when taken orally in moderate amounts. Studies lasting as long as six years have documented safe use in adults, according to the NIH. Common side effects include dizziness, gastrointestinal symptoms, and headache.

One safety concern worth knowing: ginkgo may increase bleeding risk. For this reason, the NIH advises caution in certain groups. Ginkgo may be unsafe during pregnancy because it might cause early labor or increased bleeding during delivery. Safety during breastfeeding has not been well established.

Drug Interactions

Ginkgo may interact with anticoagulant and antiplatelet drugs. The NIH specifically names warfarin as an example, noting that ginkgo may increase the risk of bleeding in people taking these medicines. Ginkgo may also interact with other medications. The National Center for Complementary and Integrative Health advises consulting a health care provider before combining ginkgo with any medication.

Omega-3 Fatty Acids (EPA and DHA)

What They Are

Omega-3 fatty acids are a family of polyunsaturated fats. The three most relevant to human health are alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). ALA is found mainly in plant oils, while EPA and DHA come primarily from fatty fish and fish oil supplements. DHA is especially concentrated in the brain, retina, and sperm, where it serves as a structural component of cell membrane phospholipids. Omega-3s also serve as a source of energy and act as precursors to eicosanoids, signaling molecules involved in cardiovascular, pulmonary, immune, and endocrine functions.

Reference Intakes

According to the NIH Office of Dietary Supplements, the Institute of Medicine set an Adequate Intake (AI) for ALA because the available data were insufficient to establish an Estimated Average Requirement or a full Recommended Dietary Allowance. The AI for ALA is 1.6 grams per day for men and 1.1 grams per day for women ages 19 to 50. No intake recommendation has been established specifically for EPA or DHA. No Tolerable Upper Intake Level has been set for any omega-3. The FDA specifies that dietary supplement labels should not recommend a daily intake of EPA and DHA higher than 2 grams from supplements. Talk with a clinician or pharmacist before choosing a specific product or amount.

What the Evidence Shows

The NIH grades the evidence for omega-3 fatty acids across several areas:

• Structural role in cell membranes, with DHA concentrated in the brain and retina: Strong evidence. This is a well-established physiological function.
• ALA as an essential fatty acid that must come from the diet: Strong evidence.
• Lowering elevated triglyceride levels with EPA and DHA supplements: Moderate evidence.
• Reducing the risk of most cardiovascular events in the general population: Limited evidence.
• Preventing cognitive decline, dementia, or Alzheimer disease: Insufficient evidence. Despite DHA's known concentration in the brain, research has not established that taking omega-3 supplements prevents cognitive decline.
• Improving infant neurodevelopment or visual development through DHA supplementation during pregnancy or infancy: Insufficient evidence.
• Slowing age-related macular degeneration: Insufficient evidence.
• Relieving symptoms of rheumatoid arthritis: Limited evidence.

Safety and Side Effects

Omega-3s from food and supplements are generally regarded as safe, and no upper intake limit has been set. Side effects from supplements are usually mild and may include an unpleasant taste, bad breath, bad-smelling sweat, headache, heartburn, nausea, stomach discomfort, or diarrhea.

Drug Interactions

Because omega-3s can reduce platelet aggregation and prolong bleeding time, combining them with anticoagulant or antiplatelet medications (such as warfarin, aspirin, or clopidogrel) or other blood-thinning herbs may theoretically increase bleeding risk. Clinical trials have generally shown that any prolongation of bleeding time did not exceed normal limits or cause clinically significant bleeding, but the NIH recommends periodic monitoring. High doses, roughly 900 mg per day of EPA plus 600 mg per day of DHA or more for several weeks, may suppress inflammatory immune responses and reduce immune function. Prescription high-dose omega-3 products used to lower triglycerides are drug-strength doses and should be taken only under medical supervision.

Key Takeaways

• Neither ginkgo nor omega-3 supplements has sufficient evidence to support a claim that they prevent cognitive decline or dementia in older adults, according to the NIH.
• DHA has a well-established structural role in the brain, but a physiological role does not automatically mean a supplement will slow or prevent age-related memory changes.
• Both supplements carry interactions with blood-thinning medications. Talk with a doctor before combining either with any prescription or over-the-counter drug.
• No standard dosing targets have been set for ginkgo. The only established reference value for omega-3s is an AI for ALA. Consult a clinician or pharmacist for personal guidance.

Sources

• NIH National Center for Complementary and Integrative Health: nccih.nih.gov/health/ginkgo
• NIH Office of Dietary Supplements, Omega-3 Fatty Acids fact sheet: ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional/
• NIH Office of Dietary Supplements, Consumer fact sheet: ods.od.nih.gov/factsheets/Omega3FattyAcids-Consumer/
• NCCIH Omega-3 Supplements overview: nccih.nih.gov/health/omega3-supplements-what-you-need-to-know
• National Academies of Sciences, Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids: nap.nationalacademies.org/catalog/10490
• ClinicalTrials.gov, Ginkgo Evaluation of Memory study: clinicaltrials.gov/study/NCT00010803