Ongoing low-grade inflammation is a key contributor to many chronic illnesses including heart disease, type 2 diabetes, inflammatory bowel disease, arthritis and depression. Cognitive decline and dementia are also tied to chronic inflammation.
Plenty of evidence suggests that certain foods and nutrients dampen inflammation in the body. Indeed, diets plentiful in anti-inflammatory ingredients have been shown to guard against a number of inflammation-related diseases.
Only a few studies, however, have investigated the link between the inflammatory potential of one’s diet and dementia risk.
Now, new findings add to growing evidence that an anti-inflammatory diet protects later-life cognitive health. They also suggest that the higher a diet’s inflammatory potential, the greater the risk of dementia.
“Inflammaging” and cognitive decline
After about age 40, the immune system begins to age. A hallmark feature of immune aging is an increased production of inflammatory immune compounds, which contributes to prolonged inflammation.
This process, called inflammaging, is thought to accelerate the aging process and increase the risk of age-related chronic disease. Brain-wise, inflammaging has been linked to cognitive impairment, vascular dementia and Alzheimer’s disease.
While inflammation is an age-related process, other contributors include environmental and lifestyle factors (for example, cigarette smoke, sedentary lifestyle, unhealthy diet, stress, poor sleep) and genetics.
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The latest findings
The research, published online this month in the journal Neurology, involved 1,059 adults, average age 73, who were enrolled in an ongoing investigation of diet and cognitive dysfunction in the Greek population.
Participants, free of dementia at the study’s onset, were followed for three years and evaluated for dementia using standard diagnostic criteria. The researchers also assessed the inflammatory potential of each participant’s diet using a tool called the Dietary Inflammatory Index (DII).
The DII is a scoring system based on 45 inflammation-promoting and anti-inflammatory food components. Diets are scored on a continuum from maximally inflammatory to maximally anti-inflammatory; a higher score indicates a more inflammatory diet and a lower score indicates a more anti-inflammatory diet.
The researchers found that each one-point increase in DII score was associated with a 21 per cent increase in dementia risk.
Participants whose diets had the highest dietary inflammatory scores were three times more likely to develop dementia over the study period than participants whose diets had the lowest inflammatory scores.
To arrive at these results, the researchers controlled for other factors associated with dementia risk, including age, sex and education.
This study was observational so it does not prove that eating an anti-inflammatory diet prevents dementia. The study was also relatively short in duration, so longer studies are needed.
Still, its findings support existing evidence that diet plays a key role in counteracting chronic inflammation and, in so doing, may be an important tool for preventing cognitive decline and dementia.
The diet-inflammation link
A diet high in calories, refined starchy foods, added sugars and unhealthy fats may cause or worsen inflammation by increasing the production of free radicals, unstable oxygen molecules that damage cells.
Consuming too much linoleic acid, an omega-6 fatty acid found in certain vegetable oils (such as soy and corn), can signal the production of inflammatory compounds in the body.
A low fibre diet may also contribute to inflammation by shrinking the diversity of beneficial microbes that reside in our gut. Fibre feeds and promotes a healthy gut microbiome.
What is an anti-inflammatory diet?
There is no single anti-inflammatory diet. Many well-researched traditional dietary patterns are anti-inflammatory such as the Mediterranean, Nordic and Okinawan diets.
The DASH diet is anti-inflammatory eating pattern, too. (DASH stands for Dietary Approaches to Stop Hypertension.) So are vegetarian and vegan diets that are based on whole foods.
An anti-inflammatory diet combines a variety of foods that provide vitamins, minerals, fibre, antioxidants and phytochemicals, all of which work together to prevent or inhibit inflammation.
Eat a variety of anti-inflammatory foods each day including colourful fruits and vegetables (dark green, bright orange, purple/blue), whole grains, pulses, nuts and seeds. Cook mainly with unsaturated oils such as olive oil, avocado oil, canola oil and grapeseed oil.
Include fatty fish like salmon, trout or sardines in your weekly diet for anti-inflammatory omega-3 fats. Flavour foods with herbs and spices, which provide anti-inflammatory polyphenols, instead of salt.
Limit your intake of foods that have a higher inflammatory potential such as red and processed meats, refined grains, sugary desserts and beverages, butter and fried foods.
Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan. Follow her on Twitter @LeslieBeckRD
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Leslie Beck