More evidence needed to confirm association between Alzheimer’s prevention and supplements like curcumin, green tea, or lion’s mane

Key takeaway

Alzheimer's disease is a progressive neurodegenerative disorder that affects memory, thinking, and behavior. There is no cure and no guaranteed method for preventing the disease, though some research suggests that maintaining healthy lifestyle habits, such as a balanced diet, regular exercise, and avoiding smoking may be associated with a reduced risk of Alzheimer’s disease. Limited evidence from animal studies and small clinical trials with humans has shown certain supplements may be associated with a reduced risk of Alzheimer’s disease, but more evidence is needed to confirm this association.

Reviewed content

Verdict:

Unsupported

Claim:

Three supplements (curcumin, green tea, and lion’s mane) can stop Alzheimer’s disease before it starts

Verdict detail

Inadequate support: There is currently genuine scientific uncertainty as to the effect of supplements such as curcumin, green tea, and lion’s mane on the prevention or progression of Alzheimer’s disease. More evidence is needed from clinical trials in humans to establish whether these associations are causal in nature.

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Full Claim

Three supplements (curcumin, green tea, and lion’s mane) can stop Alzheimer’s disease before it starts

A reel shared on Facebook in late November 2024 claimed that three supplements—curcumin, green tea, and lion’s mane—could “stop Alzheimer’s disease before it starts”. At the time of writing, it had received more than 63,000 interactions. The reel was previously shared on TikTok in December 2023, where it received thousands of interactions.

Robert W. B. Love, the speaker in the reel, described himself as a “neuroscientist [who] specialize[s] in helping people prevent Alzheimer’s disease with science”. In a previous claim review, Science Feedback found that Love doesn’t hold degrees in neuroscience, but rather cognitive psychology.

Notably, these domains differ. Cognitive psychology focuses on human behavior and understanding mental processes such as perception, memory, and decision-making, whereas neuroscience studies the biological mechanisms underlying these processes, such as the anatomy and function of the brain. Psychologists may study the mood and behavioral changes associated with Alzheimer’s disease, but unlike neuroscientists, they don’t study the cause or the mechanisms of the disease, nor do they develop treatments for it.

It’s also important to note that the U.S. Food and Drug Administration (FDA) doesn’t regulate dietary supplements as strictly as prescription drugs, meaning they don’t undergo the same level of pre-market approval or rigorous testing for safety and efficacy.

As we will explain below, there is currently no cure for Alzheimer’s disease. There is also no evidence from studies in humans showing that curcumin, green tea, or lion’s mane can prevent the onset of Alzheimer’s disease.

Is it possible to prevent Alzheimer’s disease?

Alzheimer’s disease is a progressive neurodegenerative disorder that primarily affects memory, thinking, and behavior. The disease often begins with mild memory loss and confusion, but as it progresses, individuals may experience significant cognitive decline, difficulty with daily tasks, and changes in personality. It’s the most common cause of dementia, and there is currently no cure.

Similarly, there is no surefire way to prevent Alzheimer’s disease. Alzheimer’s risk is influenced by a combination of genetic, environmental, and lifestyle factors, and research is ongoing to understand how certain strategies may play a role in reducing the risk of the disease.

Some research suggests that healthy lifestyle choices may reduce the risk of Alzheimer’s, such as maintaining a healthy diet, participating in regular physical activity, avoiding smoking, and staying mentally and socially active^[1]. Maintaining healthy blood pressure and blood sugar levels can help prevent the onset of hypertension and diabetes, which are also both risk factors for Alzheimer’s disease^[2].

Green tea

Green tea is a type of tea made from the leaves of the Camellia sinensis plant. It contains Epigallocatechin gallate (ECGC)^[3], a chemical compound capable of preventing the aggregation of tau protein in test tubes and laboratory cells^[4,5]. This protein is one of the hallmarks of Alzheimer’s and is considered to play a role in the development of the disease. According to the U.S. National Institute on Aging (NIA):

“Neurofibrillary tangles are abnormal accumulations of a protein called tau that collect inside neurons. […] In healthy neurons, tau normally binds to and stabilizes microtubules. In Alzheimer’s disease, however, abnormal chemical changes cause tau to detach from microtubules and stick to other tau molecules, forming threads that eventually join to form tangles inside neurons. These tangles block the neuron’s transport system, which harms the synaptic communication between neurons.”

Thus, some studies have evaluated whether ECGC is capable of disaggregating tau. The hope was that this effect may halt the progression of Alzheimer’s disease. However, the NIA pointed out that “EGCG is not on its own an effective Alzheimer’s treatment because it cannot easily penetrate the brain and binds to many proteins other than tau, weakening its effect.”

One preliminary study of postmortem brain tissue from people who had Alzheimer’s disease used computer simulation to determine whether molecules replicating ECGC could untangle tau fibers, given the limitations of EGCG on its own^[6]. The researchers found that some of the molecules tested did indeed untangle tau fibers, but noted that more research is needed to confirm a causal relationship.

Green tea leaves are also minimally processed and undergo less oxidation than black tea leaves, which helps preserve their natural green color and many of their beneficial compounds such as catechins, a type of polyphenol. Polyphenols are compounds found in plant-based foods that help protect cells from oxidative damage.

Some studies suggest that polyphenols like catechins may help protect the brain from oxidative stress and inflammation, two factors associated with Alzheimer’s disease.

For example, in one small study of 12 older adults with cognitive dysfunction, participants who took green tea powder for three months showed improved cognitive function^[7]. Although the study was not Alzheimer’s specific, it suggested that regular intake of green tea extract could have a protective effect on cognitive function. However, a key limitation of this study is its small sample size, which reduces the generalizability of its findings to a wider population.

Love also referenced an observational study in his reel, which found that “a thousand Japanese people found that those who drank two cups of green tea a day had a 43% reduction in their symptoms of dementia”. This may refer to a 2006 study published in The American Journal of Clinical Nutrition, which did indeed find that drinking more than two cups of green tea per day was associated with a lower prevalence of cognitive impairment^[8].

However, one limitation of this study is that it found an association, rather than a causal relationship, between green tea consumption and reduced cognitive impairment. This is typical of observational studies, which typically require randomized clinical trials to validate associations between variables^[9].

Lion’s mane

Lion’s mane (Hericium erinaceus) is an edible mushroom that was historically used in traditional Chinese medicine. It contains bioactive compounds like hericenones and erinacines that may support nerve growth factor production, which aids in nerve regeneration and cognitive function.

As Science Feedback found in a previous review, some research indeed showed that lion’s mane contains compounds that promote neuron growth and connectivity. However, these studies were conducted in animals^[10,11], which means the results may not translate to humans.

Two small clinical trials in humans did find modest evidence that consuming lion’s mane was associated with cognitive improvement^[12,13]. While these results may be promising, both studies evaluated fewer than 50 participants.

As previously mentioned, stronger conclusions can be drawn from large-scale clinical trials, which can more readily establish whether an association is causal in nature or simply coincidental. This is because large-scale randomized controlled trials randomly assign participants to different groups, which helps to minimize biases and confounding variables, in turn allowing for more reliable conclusions about cause-and-effect relationships.

It’s also worth noting that Science Feedback previously found Love sells a lion’s mane supplement online, which he claims can “help improve brain function”. It’s important to be cautious of individuals who claim to be health experts while selling supplements online as this can represent a conflict of interest.

In this instance, as outlined above, claims of the purported benefits of lion’s mane lack robust clinical evidence from human studies. More evidence is needed to determine whether lion’s mane is an effective treatment specifically for Alzheimer’s disease.

Curcumin

Curcumin, the active compound found in turmeric, exhibits anti-inflammatory and antioxidant properties. Curcumin has indeed shown potential in preventing the accumulation of beta-amyloid protein clumps in cells grown in the laboratory^[14]. These protein clumps “form plaques that disrupt cell function” and are a hallmark of Alzheimer’s disease, according to the NIA.

However, curcumin’s effectiveness in humans is limited by how well the body absorbs it, also known as its bioavailability^[15]. As with green tea and lion’s mane, more research is needed to identify whether it can in fact be an effective treatment for the prevention or progression of Alzheimer’s disease.

Conclusion

While preclinical studies have shown some promising results regarding the potential effects of curcumin, green tea, and lion’s mane in the prevention and progression of Alzheimer’s disease, the available evidence from human clinical trials remains insufficient to support the use of these supplements for preventing or treating dementia.

The few human studies conducted to date generally involved small sample sizes and showed only modest benefits in cognitive improvement. In brief, more robust, large-scale clinical trials are needed before any recommendations can be made regarding the efficacy of green tea, lion’s mane, or curcumin in treating or preventing dementia.

REFERENCES

• 1 – Dhana et al. (2020) Healthy lifestyle and the risk of Alzheimer dementia. Neurology.
• 2 – Livingston et al. (2020) Dementia prevention, intervention, and care: 2020 report of the Lancet Commission. The Lancet.
• 3 – Aboulwafa et al. (2019) A Comprehensive Insight on the Health Benefits and Phytoconstituents of Camellia sinensis and Recent Approaches for Its Quality Control. Antioxidants.
• 4 – Wobst et al. (2014) The green tea polyphenol (−)-epigallocatechin gallate prevents the aggregation of tau protein into toxic oligomers at substoichiometric ratios. Febs Letters.
• 5 – Sonawane et al. (2020). EGCG impedes human Tau aggregation and interacts with Tau. Scientific Reports.
• 6 – Seidler et al. (2022) Structure-based discovery of small molecules that disaggregate Alzheimer’s disease tissue derived tau fibrils in vitro. Nature Communications.
• 7 – Ide et al. (2014) Green Tea Consumption Affects Cognitive Dysfunction in the Elderly: A Pilot Study. Nutrients.
• 8 – Shinichi et al. (2006) Green tea consumption and cognitive function: a cross-sectional study from the Tsurugaya Project. The American Journal of Clinical Nutrition.
• 9 – Dahabreh and Bibbins-Domingo. (2024) Causal Inference About the Effects of Interventions From Observational Studies in Medical Journals. JAMA.
• 10 – Martínez-Mármol et al. (2023) Hericerin derivatives activates a pan-neurotrophic pathway in central hippocampal neurons converging to ERK1/2 signaling enhancing spatial memory. Journal of Neurochemistry.
• 11 – Lee et al. (2014) Protective Effects of Hericium erinaceus Mycelium and Its Isolated Erinacine A against Ischemia-Injury-Induced Neuronal Cell Death via the Inhibition of iNOS/p38 MAPK and Nitrotyrosine. International Journal of Molecular Sciences.
• 12 – Li et al. (2020) Prevention of Early Alzheimer’s Disease by Erinacine A-Enriched Hericium erinaceus Mycelia Pilot Double-Blind Placebo-Controlled Study. Frontiers in Aging Neuroscience.
• 13 – Mori et al. (2008) Improving effects of the mushroom Yamabushitake (Hericium erinaceus) on mild cognitive impairment: a double-blind placebo-controlled clinical trial. Phytotherapy Research.
• 14 – Giri et al. (2004) Curcumin, the active constituent of turmeric, inhibits amyloid peptide-induced cytochemokine gene expression and CCR5-mediated chemotaxis of THP-1 monocytes by modulating early growth response-1 transcription factor. Journal of Neurochemistry.
• 15 – Lopresti AL. (2018) The Problem of Curcumin and Its Bioavailability: Could Its Gastrointestinal Influence Contribute to Its Overall Health-Enhancing Effects? Advances in Nutrition.