Nutrition and Cognitive Decline

What Causes Cognitive Decline and Dementia?

Risk factors include: age, genetics, depression, cardiovascular disease, diabetes, air pollution, traumatic head injury, smoking, excessive alcohol use, diet, and exercise. It is estimated that approximately one third of AD may be attributable to modifiable lifestyle factors.

Currently, there is no cure for dementia, however, evidence suggests that nutrition may help protect against cognitive decline. In fact, the World Health Organization’s International Classification of Diseases states that nutritional deficiencies (among others) are “attributed or assumed to be attributable” to the development of dementia.

For example, low levels of vitamin D, vitamin B6, vitamin B12, and folate have all been linked to an increased risk of dementia. You can get all these vitamins from diet and/or supplementation. However, the research regarding the effectiveness of a vitamin and mineral supplementation intervention in preventing or treating cognitive decline is unclear.


Vitamin and Mineral Supplementation

In 2022, a systematic review of the research investigated whether vitamin supplements could be a solution to preventing dementia and mild cognitive impairment. They found that B-complex vitamins, particularly folic acid, may have a positive effect on delaying and preventing risk of cognitive decline. However, a 2018 Cochrane review found no such association.

Other vitamins included in the above reviews (Ex. vitamin C, vitamin E, vitamin D) did not have enough evidence to recommend supplementation for dementia prevention or treatment. Vitamin D was particularly interesting since a large body of research data exists showing associations between vitamin D status and all-cause dementia.

There are many limitations to the studies included in the two reviews. A more rigorous research methodology will be required to determine the potential benefit of vitamin or mineral supplementation in cognitive decline and dementia.

Generally speaking, dietary intervention or supplementation to ensure optimal levels of the above nutrients is safe and could benefit other areas of health. However, before supplementing, it is advised to speak with your healthcare provider to review potential benefits and risks.

How To Include Vitamin D and B Vitamins In Your Diet

Vitamin D has many other roles in health, and food sources are limited. Therefore, it is still recommended to supplement. For the average healthy adult, supplementation of 1000IU to 2000IU per day, particularly in winter, should be sufficient to prevent deficiency and obtain an overall benefit. Food sources of vitamin D include cod liver oil, salmon, tuna, fortified beverages, sardines, beef liver, egg yolks, and some fortified cereals.

B-vitamins can also be found in many foods including meat, seafood, poultry, eggs, dairy products, legumes, leafy greens, seeds, and fortified foods (Ex. Breakfast cereals and nutritional yeast). Folate (i.e. folic acid) is high in dark leafy greens, beans, peanuts, sunflower seeds, fresh fruit, whole grains, liver, and seafood. Folic acid is the supplement form and is better absorbed than folate. Generally, B-vitamin supplementation is regarded as safe, since they are water-soluble vitamins, and any excess will be excreted in your urine. However, with any supplement, make sure there is a Natural Product Number (NPN), to ensure it has been vetted by Health Canada.

Dietary Patterns: Enter the M.I.N.D. Approach

There are two main evidence-based dietary approaches that often top the list for disease prevention and management; the same is true for prevention and management of cognitive decline. The Mediterranean diet is one, DASH (Dietary Approaches for Stopping Hypertension) is the other. Both have been shown to slow cognitive decline, but neither diet was created specifically in relation to nutrition literature on cognitive decline.

Enter the MIND dietary approach.

MIND (Mediterranean-DASH Intervention for Neurodegenerative Delay) is the combination of DASH and Mediterranean diets that linked nutrition literature on dementia prevention. It was first published in 2015, and while research is ongoing as to the mechanism, it is believed to decrease oxidative stress and inflammation.


MIND encourages all kinds of vegetables, berries, nuts, olive oil, whole grains, fish, beans, poultry, and a moderate amount of wine. It recommends limiting butter, margarine, cheese, red meat, fried food, pastries, and sweets due to the large amounts of saturated and trans fats.

Overall, each dietary approach is similar and a good overall strategy.  Dietary modification and behaviour change, on the other hand, is the tricky part. 

It takes time to find a strategy that includes all the elements that underpin each of the DASH, Mediterranean, and MIND strategies. All encourage a variety of whole foods, a reduction in processed, and an increase in plant-based proteins. They are also pescatarian-leaning, meaning adding more fatty fish to the diet with a goal of 2-3 times per week.

In addition to the diet, other protective lifestyle factors highlighted by Harvard include sleep, moderate alcohol consumption, social contacts, and mental stimulation. These may altogether help to prevent cognitive decline and dementia.

In fact, even hearing loss has been established as a risk factor for dementia, potentially through diversion of cognitive process, social isolation, or potentially an underlying mechanism between both.

More research is needed to understand these complex relationships between genes and environmental factors, but it is clear that a holistic approach to diet and lifestyle has benefits.

Nutrition For Those Living with Dementia

Those who have dementia are at further risk of nutritional problems. Common tasks such as meal preparation, grocery shopping, meal scheduling, as well as appetite can become severely compromised, leading to malnutrition and the development of other health conditions. For example, nutritional intake goes down while requirements for certain nutrients may go up. Malnutrition can then lead to frailty and muscle loss, which can further impair cognition. It is a vicious circle.

According to ESPEN guidelines – in every person with dementia, screening for malnutrition and close monitoring of body weight are recommended. Supplementation of single nutrients is not recommended unless there is a sign of deficiency. In some cases, oral nutrition supplements are recommended to improve nutritional status but not to correct cognitive impairment or prevent cognitive decline.

Furthermore, caregivers themselves are at increased risk of nutritional problems, often as a result of stress and burden.

How we can help?

Both Dietitians at Preventous (Daniel Neuman RD MSc, Britney Lentz RD) are trained in evidence-based nutrition education and counseling. We can help you navigate your diet to be more in alignment with the above strategies and recommendations. If this is something you are interested in learning more about, you can book an appointment or contact Daniel Neuman TD MSC, or Britney Lentz RD here.  

Dan Neuman
Registered Dietitian MSc

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