Diet May Help Lower Genetic Alzheimer’s Risk

Taking care of our brains should be a top health priority. After all, the brain is the master controller of just about everything in our bodies. But as our age increases, so does our brain’s—and the risk of dementia.

Dementia is an umbrella term for the loss of memory and other cognitive abilities that significantly interfere with daily life. Mounting evidence suggests that dementia risk may double from the current 514,000 cases per year to twice that by the year 2060, igniting a sense of urgency in finding ways to protect the brain. 

There is plenty of research suggesting that lifestyle behaviors play a large role in brain health. For example, being sedentary may increase your risk of dementia, while moving your body more often can help mitigate the risk. High sugar intake and missing out on certain nutrients may increase your risk of dementia. Even your social life may influence your brain health, since loneliness has been shown to increase dementia risk.  

But certain aspects of brain health have a strong genetic component, especially where Alzheimer’s disease, a form of dementia, is concerned. Researchers have found over 100 genes that may raise the risk of Alzheimer’s. The most common one and the one that has the strongest impact on risk is the APOE–e4 gene. (Having a first-degree relative—parent or sibling—with Alzheimer’s significantly increases your risk for Alzheimer’s, though that does not guarantee you’ll get it.)

The APOE-e4 gene exacerbates the formation of amyloid-beta plaques in the brain, which have a connection with Alzheimer’s. It’s also strongly linked to poor regulation in lipid metabolism and impaired glucose metabolism in the brain, and glucose is the brain’s favored energy source.

Researchers at Harvard took a closer look at people with a genetic predisposition for Alzheimer’s and whether diet can help buffer your risk. They published their findings in Nature Medicine. Let’s break down their findings.

How Was This Study Conducted?

Researchers drew data from the Nurses’ Health Study (NHS), an American study using female nurses as participants that ran from 1989 to 2023. For this current study, researchers followed over 4,200 women from the NHS with an average age of 57 at baseline; during the follow-up period, 485 women developed dementia. Cognitive function was assessed in a subset of over 1,000 of these women using the standard Telephone Interview for Cognitive Status.

Researchers also performed a replication analysis using almost 1,500 men with an average age of 63 from the Health Professionals Follow-up Study (HPFS); they were followed from 1993 to 2023, during which time 121 dementia cases were identified. A replication analysis is repeating the same study to further validate the findings.  

All participants had blood work performed, from which researchers generated metabolomic data. Metabolomics is the study of metabolites and molecules. 

Participants also completed dietary questionnaires, from which researchers assessed diet quality. In this case, they used the MedDiet Index, which grades participants’ diets based on the inclusion (or absence) of foods that are common in the Mediterranean diet, including fruits, vegetables, whole grains, legumes, nuts, seeds, fish, olive oil and certain dairy products, meat and poultry. They chose the Mediterranean diet because there is evidence that it supports brain health.

What Did This Study Find?

After running statistical analyses, researchers found that individuals with greater long-term adherence to the Mediterranean diet had significantly lower risk of dementia and better cognitive function. This protection was especially noticeable in individuals with varying degrees of genetic susceptibility to Alzheimer’s disease, carrying variants of the APOE-e4 gene. These same results were replicated in the male health professionals group. 

While the Mediterranean diet as a whole was associated with a lower risk, researchers pinpointed a few components that seem to have the greatest influence. This includes fruits, nuts and monounsaturated fats, which are found in olive oil and avocados. 

One limitation of this study is that the participants were mostly highly educated individuals of European ancestry; for this reason, it is unknown if these results extend to other populations. Some of the information was also self-reported, including diet information and diagnoses, which leaves room for bias and misreporting. 

How Does This Apply to Real Life?

We know there is a connection between certain conditions and dementia. For example, we previously reported on a study that suggests that having metabolic syndrome may increase your risk of early-onset dementia by 24%. Having type 2 diabetes also increases your risk.

While genes play a role in health and disease, researchers have found that lifestyle and environment play a much larger role. And while we can’t change our genes, we can engage in lifestyle behaviors that may positively influence our health. For example, regular exercise may reduce the risk of dementia by 41% to 69%. And following the MIND diet, which is a version of the Mediterranean diet, may reduce dementia risk by 25%. 

We also know that reducing visceral (abdominal) fat and lowering cholesterol may reduce dementia risk. These can be accomplished through a balanced and varied diet, engaging in regular exercise, lowering stress and getting plenty of quality sleep. 

If you’re new to the Mediterranean diet, check out our 7-Day Mediterranean Diet Meal Plan for Beginners. If you’re ready to go deeper, try our 30-Day MIND Diet Meal Plan for Cognitive Health.

Our Expert Take

This study suggests that adhering to the Mediterranean diet long-term may significantly reduce the risk of Alzheimer’s in those with a genetic tendency for it. The Mediterranean diet is rich in fiber, antioxidants, healthy fats and lean proteins, from foods like fruits, vegetables, nuts, seeds, legumes, whole grains, seafood and olive oil. Start incorporating more of these foods into your eating pattern. If you need more individualized help, see a registered dietitian, who can help you tailor a plan to your preferences and lifestyle.