The diet that delays dementia, even for those already at risk

Read time: 3 minutes

You might wonder why the experts go on so much about diet as an important factor in dementia prevention. The reasons are very straightforward. As you age, you need your brain to be at peak performance. It needs to be plastic — to be able to adapt to the normal and expected processes of ageing — and you don't want preventable disease getting in the way of that adaptation. Diet can also act like a medication, reducing inflammation in the brain.

You can think about diet in layers when it comes to the brain. The foundation is a diet that prevents your arteries narrowing with atherosclerosis, the cause of heart disease, stroke, and vascular dementia. That means an unprocessed diet with a large variety of vegetables, red meat perhaps once a week, as little processed red meat as possible (bacon, ham and so on), and protein from legumes like chickpeas and lentils, fish and some poultry. The fat should ideally be monounsaturated, preferably from extra virgin olive oil. Keeping salt intake down matters too, and a portion-controlled unprocessed diet helps with that.

The higher the quality of the diet the lower the risk of developing dementia, and if they did develop dementia, it came on later than in those not adhering to a protective diet

The cuisine counts as well. Cooking at moderate heat or slow cooking with herbs and garlic allows the preservation, or even the development, of brain-protective substances in the pot.

The next layer is what observations and some trials of dementia prevention have found: loading that foundation with unsweetened yoghurt, leafy greens like kale, and berries such as strawberries and blueberries further reduces dementia risk. This combination is sometimes called the MIND diet.

Strong support for a high-quality diet has recently come from a Swedish study of nearly 1,900 older people who had no signs of dementia at the start. Researchers assessed their biological risk of developing dementia using blood tests, and then followed them for up to 15 years, tracking how closely their diets adhered to what is known about dementia prevention — particularly through the anti-inflammatory effect. They found that the higher the quality of the diet, the lower the risk of developing dementia over that period. And if participants did develop dementia, it came on later than in those not following a protective diet. This was particularly true for people whose blood tests suggested an elevated risk of dementia to begin with, a finding that gives the dietary message a new dimension — it is not just prevention for the general population, but potentially meaningful protection even for those who may already be on a trajectory toward cognitive decline.

The mechanisms aren't fully understood, but chronic low-grade inflammation appears to be a key pathway. A diet low in inflammatory potential consistently showed the strongest associations, in line with what we know about inflammation as a driver of neurodegeneration.