Diet and dementia
26 April 2021
We've looked at the evidence surrounding the reported benefits of different foods for preventing and delaying dementia.
Almost weekly we see a newspaper headline revealing that eating a certain food could help prevent dementia. We've waded through the evidence to bring you an overview of things you can eat to keep your brain healthy, backed by hard science.
The clearest evidence is that a Mediterranean diet – one rich in vegetables, fresh fruit, grains, unsaturated fat, olive oil, fish and beans – is good for brain health. The most recent findings published in the Alzheimer's and Dementia journal suggest that this type of diet helps lower the risk of memory and thinking issues (cognitive impairment) but does not help slow the decline once these skills are impaired.
Mushrooms: A 2019 study found that people who eat at least two 150g portions of mushrooms per week are less likely to develop mild cognitive impairment (MCI), which is often the precursor to dementia. This is thought to be due to the chemical ergothioneine, which is also found in lower levels in black beans, kidney beans, liver and kidney.
Beetroot: Betanin, found in beetroot as well as certain types of purple cacti and flowers, could help prevent dementia. Protein accumulation into plaques is a marker of Alzheimer's disease – betanin helps stop these proteins clumping together when they come into contact with the naturally occurring metals in the human body. The process is neatly explained by PhD candidate Darrell Cole Cerrato from a chemical perspective, and now evidence from an animal study supports the idea that betanin may slow the progression of Alzheimer's disease.
Eggs: Eggs, dairy and red meat are high in choline, which has been established to be beneficial for the brain. Now, a paper has demonstrated that men who eat lots of these foods are far less likely to develop dementia, due perhaps to their high choline intake. Don't worry if you follow a plant-based diet, as choline can also be found in soy-based products like tofu and soya milk, as well as dark leafy greens and kidney beans.
Turmeric: A spice used widely in Southeast Asian cooking and medicine, turmeric has antiseptic, antibacterial and anti-inflammatory properties and was suggested to help protect the brain from diseases. However, a recent review concluded that turmeric hasn't been proved to be effective against dementia, partially because not much of it actually reaches the brain.
Green and orange vegetables: Carotenoids are a type of chemical found in certain types of foods including dark leafy greens, peas, squash and sprouts. There is a body of evidence that a higher intake of carotenoids (from eating more of these foods) is associated with a lower risk of Alzheimer's disease.
Fish: Fish is a key part of the Mediterranean diet and is high in omega-3, a compound with established benefits for brain health. However, a summary by Alzheimer's Society reported mixed reviews in the benefit of omega-3 or fish for dementia, concluding that omega-3 may help prevent or delay dementia, but does not help once dementia has progressed.
Meat: A recent study of nearly half a million participants found that regularly eating highly processed meats like bacon is associated with an increased risk of dementia. Conversely, the same study found that eating lots of unprocessed red meat like pork or beef was linked to a lower risk of dementia, potentially due to its high iron and protein content. Other sources of iron include beans, nuts, dried fruit and fortified cereals; other sources of protein include dairy products, eggs, broccoli and tofu.
Many of the compounds this blog entry explores are now being investigated further to determine if a medication can be developed that utilises them. Until such a time, the best diet to have is a balanced one filled with a wide variety of foods that each offer a unique benefit to the brain. Steering clear of fatty, sugary, processed, salty foods and replacing them with nuts, fruits and vegetables is always a good idea – but it's also OK to treat yourself every now and then!