From the archives: Cognitive decline starts early, so the sooner we stave off the damage through healthy eating and exercise, the better.
Question: I’m in my 40s and have many older relatives who have dealt with dementia in their later years. Are there particular diets or foods that can reduce the risk of dementia?
Answer:
Forgetting where I’ve put my sunglasses, whether I’ve closed the garage door or what I’ve entered a room to do – I want to think my lack of attention causes these problems rather than the early onset of memory problems. But several recent studies have found our cognitive abilities slowly and steadily decline from our 20s onwards.
Indeed, our fluid cognitive abilities slowly recede between the ages of 20 and 80. Fluid cognitive abilities are the types of skills we use to read a map, make decisions such as planning a holiday and learn how to use a new smartphone. So, yes, managing that new smartphone does get more challenging in later years.
Then there’s memory – why can I still remember my childhood phone number but can’t memorise the cellphone numbers of my immediate family? A study published in the British Medical Journal found that mental processing skills, such as memory, decline in our 40s. Researchers can also spot signs of Alzheimer’s disease in people 10 years before they develop symptoms. So, destructive changes to the brain can be well under way before age 60.
If cognitive decline begins at a relatively young age, and destructive brain changes occur in early middle age, then efforts to stave off damage to our brain must likewise start sooner. And although there is no sure-fire way to prevent dementia, living a healthy, active lifestyle may help, says Alzheimers New Zealand.
Looking after our heart and blood-supply system is essential, as cardiovascular risk factors such as high blood pressure, high cholesterol levels and diabetes increase the risk of dementia. And the status of these risk factors in mid-life appears to be more critical than in older age.
So, taking steps to improve your cardiovascular health will most likely also reduce your risk of dementia. A 2016 review of evidence concluded that sticking to a Mediterranean-style diet may protect against cognitive decline and dementia.
What’s more, nutrition is known to regulate the immune system and may therefore influence the neuroinflammatory processes involved in developing Alzheimer’s disease. A review published in 2019 in the journal Current Nutrition Reports found that anti-inflammatory dietary patterns such as the Mediterranean diet and the Dash diet (Dietary Approaches to Stop Hypertension) may protect our brain.
A traditional Mediterranean dietary pattern contained olive oil, a plentiful supply of vegetables, fruit, nuts and seeds, beans, legumes and wholegrains, fish and seafood, and a limited intake of other meats and dairy.
Several dietary components, such as antioxidants and polyphenols and the omega-3 fatty acids in fish, may help inhibit inflammation in the brain associated with Alzheimer’s. For example, a US study found people who ate fish weekly had a reduced risk of cognitive decline. In addition, MRI scans revealed less deterioration of brain cells in areas associated with Alzheimer’s among regular fish eaters.
Massey University also did a clinical trial with the omega-3 fatty acid docosahexaenoic acid (DHA), in which 176 healthy adults aged 18-45 were randomly assigned 1.16g a day of DHA or a placebo. The supplementation improved memory and speed of memory in young adults whose regular diet was low in DHA.
However, modifying your overall dietary pattern to include certain foods is better than focusing on one or two nutrients. To more closely align your food intake with a traditional Mediterranean diet, eat more plant-based foods, then fine-tune the quality and quantities of other foods, as follows:
* Aim for at least 4 tablespoons of extra virgin olive oil daily as your central added fat.
* Enjoy a variety of vegetables with every meal – three servings is a bare minimum; five or more a day is better.
* Include at least 2-3 legume meals a week: add beans, lentils or chickpeas to casseroles, soups and salads.
* Eat three or more servings of fresh fruit daily.
* Eat at least 2-3 servings of fish a week, especially oily fish rich in long-chain omega-3 fats. Tinned fish is a convenient, cost-effective option if fresh fish isn’t accessible or affordable.
* Limit meat (beef, lamb, pork and chicken) to small, lean portions and consume less often. A traditional Mediterranean diet contained just 250g of meat a week.
* Snack on a small handful of tree nuts or peanuts – the Heart Foundation recommends eating 30g daily.
* Opt for wholegrain bread and cereals, including brown rice and wholegrain pasta.
* Choose 2-3 servings of low-fat dairy products a day – yoghurt, cheese and milk were a traditional part of many Mediterranean diets.
* Consume wine in moderation, if at all – traditional Mediterranean diets for men contained just one 100ml glass of wine a day. There is certainly no evidence that non-drinkers should start drinking.
* Limit soft drinks, commercial baked goods, sweets and pastries for special occasions rather than daily consumption.
This article is from the NZ Listener’s archives and was first published in its October 9, 2021, edition.
