This article was written by registered dietitian Maeve Hanan
Research is ongoing into the causes of dementia and ways to reduce the risk of developing this condition. Although there’s currently no definite way of preventing dementia, following a healthy lifestyle is associated with a lower risk.
This article will look at whether nutritional factors play a role in dementia prevention.
What is dementia?
Dementia is an umbrella term for impairments related to memory, making decisions and thinking to the point that these can interfere with everyday functioning (1).
There are a number of types of dementia, including (1):
- Alzheimer’s disease — the most common type of dementia, caused by changes in the brain.
- Lewy body dementia — when protein deposits in the brain called Lewy bodies lead to issues with thinking, behaviour, mood and movement.
- Vascular dementia — caused by reduced blood flow to the brain which leads to brain cell damage. This can occur following a stroke or related to small vessel disease.
- Fronto-temporal dementia — a rare form of dementia that can present in mid-life. This impacts the front and sides of the brain leading to changes in language and behaviour.
- Mixed dementia — when more than one type of dementia occurs at the same time. This is most likely to present in those over the age of 80.
Risk factors for dementia include: genetics, age, heart disease and brain injury. Although dementia most commonly occurs in adults over 65, this is not a normal part of the aging process.
A number of anti-inflammatory type diets have been linked with a lower risk of dementia. This may be related to preventing early changes in the brain due to less oxidation and inflammation, optimising gut health or reducing risk factors related to dementia such as diabetes and heart disease.
It’s important to highlight that most of the following research related to diet and dementia risk is observational which can’t demonstrate a clear ‘cause and effect’ link. There are also a number of other limitations with study design in this area, and overall the evidence is weaker for diet as compared with the impact of other factors such as physical activity, managing blood pressure levels, not smoking and social wellbeing (2, 3).
The mediterranean diet
A 3-year brain imaging study involving 70 middle-aged adults found that lower adherence to the Mediterranean diet adherence was associated with markers for Alzheimer’s disease (4). Whereas, higher adherence to this dietary pattern provided an estimated 1.5 to 3.5 years of protection against Alzheimer’s.
In a previous study, the same researchers also found those who followed a Mediterranean diet displayed signs of a healthier brain (thicker cortical brain regions) (5).
Following a Mediterranean diet has also been linked with a lower risk of dementia and cognitive decline in a traditional Greek Mediterranean population (6).
The Mediterranean diet is based on:
- fruit and vegetables
- beans and pulses
- oily fish
- olive oil
- nuts and seeds
- herbs and spices
The MIND diet
The MIND diet (Mediterranean-DASH Intervention for Neurodegenerative Delay) is a combination of the DASH diet for optimising blood pressure with the Mediterranean diet. This was developed relatively recently with the aim of improving brain health and reducing cognitive diseases such as dementia. As well as encouraging traditional Mediterranean foods, this diet specifically limits salt and saturated fat intake.
Following the MIND diet has been associated with a 53% reduced rate of Alzhemiers (7).
A recent systematic review also found the MIND diet to be linked with less cognitive decline as well as improved memory, attention and learning scores (8).
Checkout this article for more information about the MIND diet.
Some specific foods within the Mediterranean and MIND diets have been associated with a lower risk of dementia and improved cognitive health such as:
- fruit, vegetables and legumes (9, 10)
- fish (11, 12)
- olive oil (13)
- nuts (14)
Other dietary sources of antioxidants such as tea and coffee have also been linked with a reduced risk (15).
Other dietary approaches
There’s also ongoing research into other dietary approaches and dimension risk reduction, such as the ketogenic diet and personalised nutrition; but this evidence isn’t currently strong enough to base recommendations on (16, 17).
What about supplements & dementia risk?
A number of different antioxidants such as vitamin E, vitamin C and carotenoids have been linked with a lower dementia risk (18, 19, 20). But evidence is mixed and the jury is still out as to whether taking these in supplement form reduces dementia risk.
Omega-3 fatty acid plays an important role in brain cell function and reducing oxidative stress. Although fish that contain omega 3 (like salmon, mackerel and trout) are thought to be a key part of a healthy diet for dementia risk reduction, research related to omega-3 supplements has been mixed (21, 22).
B-vitamins play important roles in brain and nervous system function. In particular, there’s an association between low vitamin B12, folate (vitamin B 9), vitamin B6 and riboflavin (vitamin B2) levels and cognitive decline (23, 24).
Low vitamin D deficiency has also been linked with a higher risk of dementia (25).
Based on the available research there are currently no public health recommendations that advise taking specific supplements for reducing dementia risk or preventing further cognitive decline (26, 27). However, in the UK and Ireland there is a high risk of vitamin D deficiency, so supplementing with 10 micrograms during autumn and winter is advised to avoid deficiency and support bone, muscle and dental health (28).
Important: Individual advice from a registered dietitian should be sought when considering dietary supplements, as there can be risks related to this, especially when taken in higher doses.
Although the link between diet and dementia risk isn’t currently as strong as some other lifestyle prevention factors, a healthy, anti-inflammatory type diet has been linked with a lower risk of dementia — particularly the Mediterranean and MIND diets.
These dietary patterns which are based on foods like fruit, vegetables, wholegrains, legumes, fish, olive oil and nuts are also very nutritious and linked with a number of other health benefits and supporting overall health.
There’s a possible link between certain supplements and a reduced dementia risk, due to their role in preserving brain health. But the evidence currently isn’t strong enough to recommend any specific supplement for this purpose. So it’s best to focus on a balanced and varied Mediterranean/MIND-style diet.
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Diet and dementia prevention was last modified: September 15th, 2022 by