Mediterranean diet and dementia

The best way to reduce your risk of dementia is to adapt various aspects of your lifestyle, including eating certain foods, taking regular exercise, not smoking, and maintaining normal blood pressure and cholesterol levels.

There is some evidence that eating a Mediterranean-style diet can reduce the risk of developing problems with memory and thinking, and getting some forms of dementia.

Mediterranean diets are traditionally high in fruits, vegetables, legumes and cereals, with moderate consumption of oily fish and dairy, and low in meat, sugar and saturated fat. Most fat in this type of diet comes from olive oil, and alcohol is consumed in moderation with meals. Research in the 1960s showed that men from Mediterranean regions who adhered to traditional diets had lower rates of heart attacks. This prompted continual investigation into the potential health benefits of the diet.

Investigations have shown that this kind of diet is associated with lower levels of stroke, type 2 diabetes, cardiovascular diseases and death from any cause. They have also shown that sticking to the diet more strictly might be associated with slower rates of decline in memory and thinking.

Mediterranean diets and dementia risk

A recent study pulled together all the existing evidence about the Mediterranean diet relating to problems with memory and thinking and dementia, to assess the potential benefits. This type of study is called a systematic review. A systematic review is a good tool for evaluating existing evidence and understanding where a consensus lies, if there is one. A lot of research was not included in this study because it was not stringent enough or it did not look at the diet as a whole. The studies that remained seem to show an association between the Mediterranean diet and lower levels of memory and thinking problems.

Why Mediterranean diets might affect dementia risk

High levels of antioxidants from the high intake of fruits and vegetables may help to protect against some of the damage to brain cells associated with Alzheimer's disease, as well as increasing the levels of proteins in the brain that protect brain cells from this damage. Inflammation in the brain is associated with Alzheimer's disease (although in this context we mean chemical changes within the brain's immune system, rather than swelling). There are suggestions that the diet reduces the signs of this inflammation. The diet is also linked to lower levels of cholesterol, which recent research has suggested may be associated with memory and thinking problems.

Although the evidence from this analysis of multiple studies is very promising, it is worth noting that other recent large studies have not shown similar trends. It is also important to recognise that the studies were observational so they are unable to show any direct cause and effect in the way that a trial might. This means that people who follow Mediterranean diets may lead healthier lifestyles in general, so it may be this – rather than the diet itself – that causes the difference in memory and thinking problems.

For most people, following the Mediterranean diet is a good way to ensure a healthy diet, which may be important for maintaining good brain function.