According to research, the main cause of dementia is damage to brain cells. Damaged cells cannot send signals and communicate with each other, disrupting cognitive processes such as thinking and emotional regulation. Because the brain has many distinct regions each with its own specific function (e.g., memory, judgment, movement, etc.), dementia symptoms vary depending on which brain region's cells are damaged.
Multiple risk factors are said to contribute to the development of dementia. A study published in the journal Nutrients noted that while some factors, such as genetics, advanced age and family history, cannot be modified, other factors are modifiable. In 2017, a panel of experts identified nine modifiable risk factors of dementia, namely, depression, diabetes, hearing impairment, hypertension, low social contact, obesity, physical inactivity, poor education and smoking.
In 2020, experts updated this list to include air pollution, excessive alcohol consumption and traumatic brain injury. But more recently, researchers have begun exploring the role of diet and nutrient deficiencies in triggering the development of dementia. Subsequently, experts have begun to recognize the importance of nutrient supplementation as a possible solution to prevent cognitive decline. (Related: Dementia or something else? See which health conditions that are often mistaken for the degenerative disease.)
Link between nutrition and dementia
Preclinical studies have shown that certain nutrients can help modulate brain aging. Some of the most important brain nutrients identified by researchers include B vitamins (B6, B9 and B12), vitamin D, omega-3 fatty acids and plant-derived nutrients (phytonutrients) with antioxidant properties, such as carotenoids and polyphenols. Because nutrients normally interact with other nutrients inside the body, multiple-nutrient supplementation, particularly of the aforementioned nutrients, appear to work significantly better than single-nutrient supplementation.
In a new study published in the journal Alzheimer's & Dementia, a team of American and Dutch researchers attempted to shed more light on the "complex interactions between multiple-nutrient suboptimal statuses and cognitive aging." To achieve their objective, they developed a nutrient status index that includes three nutrient biomarkers, namely, homocysteine (for vitamins B6, B9 and B12), vitamin D and omega-3 fatty acids. They then associated this index with the incidence of dementia in the Framingham Heart Study Offspring cohort, a prospective community-based cohort.
Among the 968 study participants, the researchers reported that 79 developed dementia over a median follow-up of 15.5 years. They also found that concurrent nutrient deficiencies are associated with dementia risk. Participants with a higher index, which meant suboptimal homocysteine, vitamin D and omega-3 status, had a higher risk of developing dementia than participants with a lower index. A combined suboptimal status for B vitamins, vitamin D and omega-3s was also associated with a four-fold increase in dementia risk. (Related: Research shows Lion’s mane mushroom can combat dementia and cognitive decline.)
In addition, the researchers found that being a carrier of the APOE ?4 allele, the strongest genetic risk factor for Alzheimer's disease, influenced the association between nutrient status index and dementia risk. They noted that while being a smoker and having diabetes doubled the dementia risk of participants, having the APOE ?4 allele tripled their risk. Prompted by these findings, the researchers emphasized the importance of dietary interventions coupled with dietary supplementation to address nutrient deficiencies and lower one's risk of developing dementia.
Nutrients for a healthy brain
As mentioned in the study, having healthy levels of B vitamins, vitamin D and omega-3 fatty acids is important for maintaining healthy brain functions as you age. This is because these nutrients play distinctive roles in the process of brain aging. Brain aging, according to studies, occurs through multiple, dynamically interacting mechanisms that require the involvement of the abovementioned nutrients.
Vitamin D is an important nutrient not just for supporting brain health but also for maintaining strong bones and teeth and a robust immune system. Research suggests that vitamin D promotes healthy brain aging because it helps reduce oxidative stress and brain inflammation, regulates calcium homeostasis and suppresses amyloid beta deposition. The deposition of amyloid beta is believed to play a central role in the pathogenesis of Alzheimer's disease.
In a recent study, researchers at Tufts University in Massachusetts looked at four regions of the human brain that are associated with changes linked to Alzheimer's disease. They found that vitamin D is present in all four brain regions and that individuals with high vitamin D concentrations in those regions have better cognitive functions than those with lower concentrations. (Related: Vitamin D supplementation found to prevent decline in memory and learning, research finds.)
Unlike other vitamins, vitamin D is naturally produced by the human body, specifically in the skin, upon exposure to ultraviolet B rays from the sun. To maintain healthy vitamin D levels, experts suggest exposing your skin to the sun for at least 13 minutes around midday every day. You can also include fatty fish (e.g., salmon and sardines) and fish liver oils in your diet as well as egg yolks, cheese and beef liver.
Omega-3 fatty acids are known for their anti-inflammatory properties and their ability to support cardiovascular health. The omega-3s you get from food are actually incorporated into the cell membranes of all tissues in your body. Enrichment of these membranes with omega-3s is said to result in better cell signaling or communication, membrane protein function and gene expression.
According to studies, lipids comprise approximately 50 to 60 percent of the brain's weight, and about 35 percent of these lipids are omega-3s. Of the three main types of omega-3s -- docosahexaenoic acid (DHA), alpha-linolenic acid (ALA), and eicosapentaenoic acid (EPA) -- DHA accounts for more than 40 percent of the total omega-3s in brain cells. Omega-3s support healthy cognition by promoting optimal brain cell function and protecting brain cells from neurodegeneration.
The best sources of DHA and EPA are fatty fish like mackerel, salmon, herring, sardines and anchovies. Oysters also contain decent amounts of omega-3s. Plant-based foods like flaxseed, chia seeds, walnuts and soybeans, on the other hand, are excellent sources of ALA. ALA can be converted by the body to DHA. Studies also show that ALA could help protect against Alzheimer's disease by improving blood-brain barrier function.
B vitamins are water-soluble nutrients that play crucial roles in various metabolic processes. Because they cannot be stored by the body, you need to get them daily from the foods you eat. Vitamins B6, B9 and B12, in particular, are involved in the production of chemicals that help regulate brain processes, which is why maintaining healthy levels of these nutrients is extremely important. In fact, having low levels of these vitamins is linked not only to cognitive decline but also to depression.
According to a meta-analysis published in the journal Nutrition Reviews, long-term B vitamin supplementation can help slow cognitive decline among healthy older adults. They also noted that in non-dementia populations, lower vitamin B9 (folate) levels and higher homocysteine levels were associated with higher risks of dementia and cognitive decline. Among adults 50 years and above, higher intake of folate significantly decreased dementia risk, suggesting a potential role for this nutrient in dementia prevention. (Related: Study reveals B VITAMINS may reduce glaucoma risk.)
Vitamin B6 can be found in a variety of foods, such as pork, poultry, peanuts, soybeans, oats, bananas and milk. Vitamin B9 can be found in abundance in dark green leafy vegetables, nuts, beans, peas, seafood, eggs, dairy products, poultry, meat and whole grains. Vitamin B12 can be obtained from organ meats, clams, sardines, beef, milk and dairy products, eggs and oily fish like salmon and trout.
Nutrition plays a huge role in the maintenance of healthy brain functions. For healthy brain aging, eat a well-balanced diet rich in nutritious foods and seek guidance from a health professional about taking dietary supplements to help meet your nutritional needs.
Brain.news has more stories about how to keep your brain healthy.
Watch this video to learn more about dementia risk and cognitive health – issues, solutions and how to prevent brain disorders.
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Sources include:
Alz-Journals.OnlineLibrary.Wiley.com
NutritionSource.HSPH.Harvard.edu
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