Can a healthy diet reduce Alzheimer’s risk?

Alzheimer’s disease mainly affects older adults. As the average age of many global populations grows, scientists expect case numbers to rise.

Today, an estimated 6.7 million people in the United States and 900,000 people in the United Kingdom are living with Alzheimer’s.

It’s the most common form of dementia, accounting for around 60–80% of dementia cases.

What’s Alzheimer’s?

In brief, Alzheimer’s is caused by damage to nerve cells, or neurons, in the brain.

Experts believe that this damage stems from a buildup of particular proteins within and between neurons. With time, the level of damage increases.

Early symptoms include memory problems, apathy, and depression. 

Current treatments can help slow the progression, but there’s no cure.

Some scientists are designing better treatments, others are exploring the risk factors, and still others are looking at whether our diets play a role.

In this article, we’ll investigate links between nutrition and Alzheimer’s risk. 

A cautionary note

Before jumping in, we need to clarify that scientists are still fleshing out the links between nutrients, dietary patterns, and dementia. 

There’s no set-in-stone, evidence-based anti-Alzheimer’s diet. We’re not there yet.

Still, scientists have much more work to do. In particular, we need longer and larger studies.

Plus, everyone’s different, so a dietary pattern that protects one person might not be as effective for someone else.

Alzheimer’s and nutrition

A recent review of 38 studies, published in 2023, investigated links between Alzheimer’s and nutrition. 

Let’s look at some of the specifics they covered.

Carbs and blood sugar

The review’s authors concluded that a diet high in refined carbs or a high-glycemic index diet is linked to an increased buildup of Alzheimer’s-related proteins in the brain. 

High-glycemic index foods cause your blood sugar levels to rise quickly. This is because they contain carbs that our bodies digest fast. Baguettes, potatoes, and white bread are examples of these foods, and soda also ranks high on the glycemic index.

Interestingly, this gene variant is also linked to an increased risk of developing insulin resistance — the forerunner to type 2 diabetes.

In the U.S., around 20–30% of people have one or two copies of APOE-e4.

The Western diet

The review’s authors observe that the Western diet increases Alzheimer’s risk.

In part, this might be because the diet includes a high percentage of calories from ultra-processed foods. 

And some studies show that consuming more ultra-processed foods is associated with a higher risk of dementia. 

If you’d like to learn more, ZOE has an article on the links between ultra-processed food and brain health as you age.

Omega-3s

A number of studies have investigated whether omega-3 essential fatty acids might reduce the risk of developing Alzheimer’s disease.

The three main types of omega-3s are alpha-linolenic acid (ALA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA). 

ALA comes from plants, and DHA and EPA are mostly found in fatty fish.

The authors of the 2023 review write: “Adequate levels of omega-3 polyunsaturated fatty acids, especially EPA and DHA, are associated with slower rates of cognitive decline and reduced risk of [Alzheimer’s disease].” This is born out by other research.

Meanwhile, some scientists are also investigating whether omega-3 supplements might help reduce symptoms in people with early stage Alzheimer’s. So far, though, the evidence is mixed.

Dietary patterns

Another review, published in 2019, took a slightly different approach. The authors focused on specific dietary patterns and Alzheimer’s risk. They reviewed 26 studies.

Let’s look at some of the dietary patterns they examined.

The Mediterranean diet

The Mediterranean diet generally contains plenty of vegetables, legumes, whole grains, nuts, olives, and olive oil. 

It also includes moderate amounts of fish and fat-free and low-fat dairy products, as well as small amounts of red and processed meats.

The authors of the review conclude that following the Mediterranean diet more closely seems to be linked to a reduced risk of Alzheimer’s.

The review’s authors believe that the Mediterranean diet lowers the risk because it’s linked to reduced inflammation and oxidative stress, both of which are central to Alzheimer’s progression.

The DASH diet

The Dietary Approaches to Stop Hypertension (DASH) diet is low in saturated fats, overall fat, and red and processed meats. It’s rich in fruits, vegetables, whole grains, and low-fat dairy.

Designed more than 20 years ago, the DASH diet effectively reduces high blood pressure.

Again, the review's authors suggest that this is because it reduces inflammation and oxidative stress.

The MIND diet

Thankfully, the Mediterranean-DASH Intervention for Neurodegenerative Delay Diet is tidily abbreviated to the MIND diet.

As the name implies, this dietary pattern has elements of the Mediterranean and DASH diets. 

In particular, it focuses on plant foods linked to dementia prevention, including:

• leafy green vegetables

• other vegetables

• berries

• whole grains

• beans

• nuts

• one glass of wine a day

• olive oil

The MIND diet also contains small amounts of fish and poultry but limits the intake of red meat, sweets, pastries, cheeses, fried food, butter, and margarine.

The link may stem from a reduction of inflammation and oxidative stress and an increased intake of omega-3s, the authors suggest.

What to make of it all

Because there’s no cure for Alzheimer’s, and current treatments are far from perfect, the conclusions of these reviews are good news.

However, the authors of both explain that more research is needed. Drawing solid conclusions will require more investigations into the links between different dietary patterns and Alzheimer’s. 

At ZOE, we know that increasing your intake of plants is likely to have a range of health benefits. The same is true of reducing your intake of ultra-processed foods.

So, if you’re considering changing your diet, upping your plant intake is a safe bet. It’s likely to do your health a favor, and it might reduce your Alzheimer’s risk, too.