The Connection between Diet, Inflammation and Brain Health

Recently, the scientific journal Neurology published a new study that illuminated the relationship between diet, inflammation and the aging process—in particular, the risk for development of dementia in older adults. To discuss the implications, Leslie Beck, RD, Medcan’s Director of Food and Nutrition, sat down with Medcan Chair, CEO and Eat Move Think host Shaun Francis. Here’s an edited version of their conversation.

Shaun Francis: Leslie, inflammation has become a hot topic recently. Before we really dive into things, can you start by explaining a bit about inflammation and what it is?

Leslie Beck: Acute inflammation can actually be a good thing, as it is the process that results when the body’s immune system is activated in response to an injury or illness—say, when you catch a cold or get a paper cut. The immune system’s activation helps to heal injury or illness and fight off infection. Once the body heals from the injury or illness, the immune system response should turn off, causing the inflammation to subside. In such cases, the inflammation is short-lived—it’s a healthy response to injury and infection.

Chronic inflammation, however, occurs if the immune system’s response doesn’t subside and inflammation continues. This can silently damage cells and can also increase the risk of illness. This ongoing low-grade inflammation is thought to contribute to the development of many chronic conditions, like coronary heart disease, Type 2 diabetes, inflammatory bowel disease, depression and Alzheimer’s disease.

SF: So what can cause this ongoing inflammation?

LB: Many things contribute to chronic inflammation including stress, poor diet, sedentary lifestyle and cigarette smoking. Certain illnesses can cause chronic inflammation, too.

SF: Now that we have a good handle on what inflammation is, what’s the relationship between inflammation and aging?

LB: Around the age of 40, our immune system begins to age. And one of the key features of immune aging is an increased production of inflammatory compounds, which contributes to prolonged inflammation. This process is called “inflammaging”—and it’s thought to accelerate the aging process and increase the risk of age-related chronic disease. When it comes to our brain health, inflammaging has been linked to cognitive impairment, vascular dementia and Alzheimer’s disease.

SF: Alright, so let’s dive into the details of the Neurology study that illuminated the relationship between diet, inflammation and brain health.

LB: The study was published in November 2021 and investigated the link between the inflammatory potential of diet and the risk for dementia. It was conducted in 1,059 adults, with an average age of 73, living in Greece who did not have dementia at the start of the study. The researchers followed these people for three years, evaluating for dementia using standard diagnostic criteria. They also assessed the participants’ diets using questionnaires. The researchers used that information to calculate the inflammatory potential of their diets with a tool called the Dietary Inflammatory Index (DII).

SF: How does the Dietary Inflammatory Index work?

LB: It’s an online risk calculator, which we actually use with our clients at Medcan. The scoring system is based on 45 inflammation-promoting food components and anti-inflammatory food components. Basically, a high score indicates a more inflammatory diet, whereas a lower score indicates a more anti-inflammatory diet. The tool was developed by researchers at the University of South Carolina and has been used in over 225 scientific papers.

SF: So, what did the study discover?

LB: After the three-year study was complete, the researchers found that the participants whose diets had the highest dietary inflammatory score were three times more likely to develop dementia over the study period compared to participants whose diets had the lowest inflammatory scores. They also found that every one-point increase in the DII score was associated with a 21% increase in dementia risk. These findings really do support existing evidence that diet plays an important role in counteracting inflammation in our body and, in doing so, may help prevent cognitive decline as well as dementia.

SF: So how can our diet cause inflammation in the body?

LB: Our diet works in a few different ways to either promote inflammation or reduce it. For example:

• A diet with too many calories, too many refined grains, too many added sugars and/or too many unhealthy fats can contribute to inflammation by increasing the production of free radicals in our body. Free radicals are unstable oxygen molecules that can damage cells.
• Consuming too many foods that contain a lot of a specific omega-6 fatty acid called linoleic acid, which is high in soybean oil and corn oil (often found in processed foods), can increase the production of inflammatory compounds in your body, particularly if you don’t consume enough anti-inflammatory omega-3s.
• A low-fibre diet can contribute to inflammation by reducing the diversity of beneficial gut microbes. Fibre helps promote a diverse array of gut microbes, which can help play a role in reducing inflammation.

SF: So then, what’s a good anti-inflammatory diet to follow?

LB: There really isn’t one anti-inflammatory diet. It’s your overall pattern of eating that matters. A diet that includes food and food components that reduce inflammation and limits foods that promote inflammation is what’s important. Some examples of dietary patterns to follow would be the Mediterranean diet—which is the most studied—as well as the Nordic diet, the Okinawan diet, the DASH diet, or a vegetarian or vegan diet that’s based on whole foods. The MIND diet (Mediterranean-DASH Intervention for Neurodegenerative Delay) is another great example, especially when it comes to brain health. This dietary pattern is a hybrid of the Mediterranean and DASH diets, plus it also includes specific foods that have been linked optimal brain health in past studies. The MIND diet has been linked to slower cognitive decline and a lower risk of Alzheimer’s disease in older adults. These findings come from observational studies, but the MIND diet is currently being investigated in rigorous randomized controlled trials.

SF: So, what does a MIND diet look like?

LB: For one, it includes lots of leafy greens, like spinach, rapini, kale and Swiss chard, at least six times a week. They’re very high in antioxidants, but one particular antioxidant—lutein—has recently been shown to play an important role in keeping our brains healthy.

Other MIND-diet brain-healthy foods we should be regularly eating include:

• Berries, at least twice a week
• Beans and lentils, at least four times a week
• Whole grains, at least three times a day
• Nuts, at least five times a week
• Fish, at least once a week
• Brain-unhealthy foods to limit include red meat and processed meats, fried and fast-foods, butter and margarine and sweets and pastries.

SF: So where do you suggest starting if you want to eat an anti-inflammatory diet?

LB: 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. Instead of salt, flavour foods with herbs and spices, which provide anti-inflammatory polyphenols.

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.

Learn more about how our nutrition programs can support your overall wellness goals. Book an appointment by getting in touch with us at nutrition@medcan.com or 416.862.1553. Follow Leslie Beck on Twitter @LeslieBeckRD.