A new study published in the peer-reviewed journal Neurology suggests that eating more plants can help guard against dementia.Mila Drumeva/iStockPhoto / Getty Images
Diets plentiful in plant-based foods have been tied to several health advantages.
A plant-forward eating pattern has been associated with lower risk of Type 2 diabetes, heart disease, stroke, certain cancers and premature death. It’s also been linked to slower cognitive decline.
Now, a new study published in the peer-reviewed journal Neurology suggests that eating more plants can also help guard against dementia.
There’s one caveat, though.
Simply eating more plant-based foods isn’t enough. The quality of those plant foods matters.
Here’s a breakdown of the study, along with simple ways to add the right plant foods to your diet.
What the research says
The study, published in early April, examined whether the quality of plant‑based diets matters for dementia risk, and if improving – or worsening – plant quality over time influences that risk.
The researchers followed 92,849 U.S. adults, living in California and Hawaii, for nearly 11 years. Participants’ diets were assessed at baseline and again at the end of the follow-up period.
Diets were scored using three plant-based diet indices that distinguish how plant‑based a diet is overall, regardless of quality, how rich it is in high-quality plant foods and how heavily it relies on unhealthy plant foods.
What is a ‘healthy’ vs. ‘unhealthy’ plant-based diet?
High-quality plant foods include whole grains, vegetables, whole fruit, nuts, pulses, vegetable oils, coffee and tea.
In contrast, poor-quality plant-based foods are those high in added sugars, refined (white) grains, fruit juice and potatoes, including fried and processed potatoes.
A smoothie made with frozen berries, spinach and ground flax, for example, would increase a diet’s healthy plant-based index score whereas a bottled smoothie made with fruit juice would move its score in an unhealthy direction.
Diet changes, even later in life, influenced dementia risk
During the follow‑up period, 21,478 participants developed Alzheimer’s disease and related dementias.
Participants whose diets were richest in plant foods overall – regardless of quality – had a 12-per-cent lower risk of developing dementia compared with those who consumed the fewest plant‑based foods.
Those with the highest intake of unhealthy plant‑based foods, however, had a six per cent higher risk of dementia.
Notably, the research found changes in plant‑based diet quality over time – including later in adulthood – were strongly tied to subsequent dementia risk.
Participants whose intake of unhealthy plant‑based foods increased substantially during the study had a 25 per cent higher risk of dementia compared with those whose diets remained relatively stable.
On the other hand, a large decrease in the consumption of unhealthy plant‑based foods was linked to an 11 per cent lower dementia risk.
People who cut back sharply on healthy plant foods over time were 17 per cent more likely to develop dementia.
When the researchers looked at specific foods, a reduced intake of several healthy plant foods – including whole grains, vegetable oils, nuts, tea and coffee – was tied to a greater risk of dementia.
Plant foods high in added sugars were the only unhealthy plant foods consistently associated with a greater risk of dementia. Higher intakes were tied to a 12-per-cent increased risk.
The findings were generally consistent regardless of sex, age, body mass index and genetic risk for Alzheimer’s disease.
The study’s strengths include its large number of participants from diverse racial and ethnic groups and its long-term follow-up.
It looked not only at plant‑based eating, but also at the quality of plant foods and how participants’ diets changed over time.
While the findings suggest important links between plant‑based diet quality and dementia risk, the study was observational and can’t prove cause and effect.
Even so, the results add to previous evidence that diet patterns that emphasize high-quality plant-based foods are associated with better cognitive function.
Simple ways to eat more high-quality plant foods
Healthy plant-based foods supply the brain with vitamins, minerals, antioxidants and anti-inflammatory phytochemicals, which nourish and protect brain cells.
Fibre-rich and nutrient-dense plant foods also support metabolic health, which is closely linked to cognitive health.
Swap white bread, rice or pasta for whole grain versions more often. Add cooked quinoa, bulgur or farro to soups and green salads. Blend dry rolled oats into smoothies.
Stir lentils or white kidney beans into soups and pasta sauces. Toss chickpeas into a Greek salad. Add black beans or pinto beans to tacos, grain bowls and salads.
Set a goal to eat one more vegetables each day. Add baby spinach to scrambled eggs or shredded cabbage into sandwiches and wraps.
Top homemade pizza with baby arugula. Mix pumpkin puree into overnight oats.
Snack on whole fruit instead of granola bars or white crackers. Dip apple or pear slices into Greek yogurt or enjoy them spread with nut butter.
Add toasted nuts or seeds to salads, oatmeal and yogurt. Stir cashews into stir-fries. Blend flax meal, chia seeds or hemp seeds into protein shakes and smoothies.
Use plant-based oils for cooking and salad dressings, such as olive, avocado, peanut, canola or grapeseed oil.
Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan.