Can Your Diet Impact Your Risk for Alzheimer’s Disease?
In recognition of Alzheimer's and Brain Awareness Month we will examine the impact of controllable lifestyle habits such as diet, exercise and cognitive/social stimulation on your risk for Alzheimer’s disease later in life.
Alzheimer's is a progressive disease where brain cells degenerate and die, which destroys memory and other important mental functions. As more and more brain cells die, it leads to significant brain shrinkage.
Initially, one may notice mild confusion and difficulty remembering small things – but over time they may even forget important people in their lives, how to cook, get dressed, or clean and undergo significant personality changes.
Those with Alzheimer’s may experience depression, severe social withdrawal, mood swings, minimized reasoning and planning skills, distrust in others, irritability, changes in sleeping habits and various delusions.
There is still no known cure for the disease - so it is important to understand how to lower your risk from such a sad and destructive ailment. Scientists believe the disease is caused by a combination of genetic, lifestyle and environmental factors that affect the brain over time.
Essentially, most indicators of heart or metabolic disease that have a negative impact on the vascular/nervous systems seem to be associated with an increased risk for Alzheimer’s. This indicates a close connection between cardio-metabolic and neurodegenerative disease.
Dietary Considerations for Alzheimer’s Disease
In the following, we will take a deeper look at the potential impact of dietary measures on Alzheimer’s risk. Research suggests eating certain foods may help keep the brain healthy, while others are detrimental to cognitive health. A diet rich in fruits, vegetables, and whole grains that is also low in poor-quality fat and added sugar can reduce the risk of many chronic diseases, including those which impact the brain.
Scientists have examined many aspects of dietary intake, and the following suggestions from a literature review, including a summary publication from the journal Neurobiology of Aging, may help point individuals in the right direction for reducing their risk for Alzheimer’s disease and boosting their brain health.
Note that much of the science concerning nutrient intake and Alzheimer’s is not yet fully conclusive or understood, but some elements of dietary intake seem to increase one’s risk more than others.
- Minimize saturated and trans fat intake:
- Several investigations, such as the Chicago Health and Aging Project, have indicated up to a 2x increased risk for developing Alzheimer’s disease among individuals who consume the most saturated fat (≥80th percentile).
- Many well-controlled studies concerning cognitive decline have found high saturated fat intake increases the rate of decline with age.
- Other research observation indicate high-fat food may contribute to beta-amyloid production or aggregation in brain tissues.
- Interestingly, in one study, scientists fed rats a “Western” diet high in fats and simple carbohydrates for 90 days. The rats performed significantly worse on memory tests that involve the hippocampus - a part of the brain that plays a major role in learning and memory.
- Sugar and fat should be minimized to reduce the risk for major diseases, including those which impact the brain.
- Focus on plant-based foods:
- Vegetables, legumes, fruits, nuts and whole grains should replace meats and full-fat dairy products as primary staples of the diet as they provide micronutrients (e.g., folate, vitamin B6, vitamin B12) and antioxidant phytochemicals critical to brain health while containing little to no saturated/trans fats.
- The Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet promotes these foods while suggesting a limitation on red meat, butter, pastries, fried foods and high-fat dairy.
- An epidemiological study also reported that people who followed a “Mediterranean diet” had a 28% lower risk of developing mild cognitive impairment (MCI) and a 48% lower risk of progressing from MCI to Alzheimer’s disease. This diet includes vegetables, legumes, fruits, cereals, fish, olive oil, low-to-moderate alcohol, and low amounts of saturated fat, dairy, meat and poultry.
- Plant-based foods in general are associated with a reduced risk of cardiovascular disease, obesity, and type 2 diabetes – all indirectly associated with brain diseases.
- Try to obtain 15mg of vitamin E from whole foods daily:
- Vitamin E from whole foods is preferred over supplements as most do not replicate the range of forms found in natural sources. Healthful food sources include seeds and nuts (highest), spinach, mangoes, peppers and whole grains.
- Note that research does not conclusively suggest that vitamin E directly reduces the risk for Alzheimer’s (especially supplements) or have a preventative function; however, several studies have shown higher intakes of vitamin E from food being associated with a reduced risk for dementia in general.
- It is a powerful antioxidant and healthful dietary element.
- Consider a B12 supplement as you age (>50):
- Vitamin B12 is essential for brain and nervous system health as well as blood cell formation. As mentioned earlier, many plant-based foods are rich in B-vitamins, along with various fortified foods and meats.
- Unfortunately, absorption from these sources is limited in many individuals – hence the recommendation for supplementation. Those who are >50 years old, suffer from reduced stomach acid production, take certain medications, have had gastrointestinal surgery or have Crohn’s/celiac disease cannot absorb B12 effectively.
- Vitamin B12 aids in the regulation of homocysteine - and elevated homocysteine levels are suggested to increase the relative risk for cognitive impairment or dementia, per some studies.
- One systematic literature review of over 43 studies showed an association between low vitamin B12 levels, neurodegenerative disease and cognitive impairment.
- The major consensus is that there is a small subset of dementias that are reversible with vitamin B12 therapy, but vitamin B12 does not improve cognition in patients without pre-existing deficiency. One needs to maintain normal levels as a preventative measure before dementia begins to present itself.
- Scientists agree that more large, well-resourced clinical trials are needed to close the gaps in our current understanding of vitamin B12 insufficiency and neurodegenerative disease.
- Consider avoiding multi-vitamin/mineral supplements with iron and copper:
- If using a multivitamin, choose those without iron and copper if possible, and consume iron supplements only when directed by your physician.
- Iron is essential for formation of hemoglobin, and copper plays an essential role as an enzyme co-factor (energy metabolism and other functions). However, research suggests excessive iron and copper intake may contribute to cognitive problems for some individuals.
- In recent meta-analyses, circulating non-protein-bound copper was associated with Alzheimer's disease risk.
- In the Chicago Health and Aging Project, individuals with a high intake of saturated fat and copper were found to have a theoretical cognitive decline equivalent to 19 additional years of aging.
- Essentially, one should be careful with high intake of most metals that can increase the risk for toxicity and accumulation in certain systems – incidentally promoting unintended changes in physiology. Other aspects of the diet may play a modulating role in the relationship between metals and cognitive effects.
- Consider the controversy surrounding aluminum:
- While aluminum’s role in Alzheimer’s disease remains inconclusive, those who desire to minimize their exposure can avoid the use of some cookware, antacids, baking powder or antiperspirants.
- Some researchers have called for caution, citing aluminum's neurotoxic potential and the fact that aluminum has been demonstrated in the brains of individuals with Alzheimer's disease (even though the data in these early studies is claimed to have been skewed).
- Furthermore, a 2009 study found increased Alzheimer's prevalence in regions of Europe where tap water contained higher aluminum concentrations.
- However, because of the limited number of relevant studies, most experts regard current evidence as insufficient to accuse aluminum as a contributor to Alzheimer's disease risk.
- Antioxidants and glass of red wine won’t hurt:
- Antioxidants combat damage caused by free radicals. With age, it is suggested that free radicals can build up in nerve cells, causing damage that might contribute to Alzheimer’s.
- Some epidemiological and laboratory studies suggest that antioxidants from food or dietary supplements help prevent this oxidative damage, but other studies have shown no effect.
- Vitamin E, vitamin C, B vitamins, ginkgo biloba, and coenzyme Q have all been tested in clinical trials, but none has proven effective in preventing or slowing down Alzheimer’s.
- However, observational studies concerning resveratrol (a compound found in red grapes) have shown that moderate consumption of red wine is associated with a lower incidence of Alzheimer’s disease. Animal studies have also shown resveratrol to reduce beta-amyloid deposits in the brain. Furthermore, a 2017 study published in the Journal of Nueroinflammation found resveratrol to be viable target for treatment or prevention of neurodegenerative disorders.
So, as one can see there are various dietary elements to consider, but there is clearly no one magic food a person can eat to directly lower their risk for Alzheimer’s.
Take Home Message:
In a subsequent Alzheimer's and Brain Awareness Month discussion we will address research on the physical and cognitive activity side of the equation for protecting one’s brain from dementia and Alzheimer’s disease.