Malnutrition may drive onset of disease

By Staff 9 Min Read

  • Malnutrition may drive the onset of Alzheimer’s disease, and the disease’s progression then increases malnutrition, according to a new study from China.
  • The hope is that better addressing people’s nutritive needs will reduce the incidence of Alzheimer’s disease and other dementias.
  • Two diets were investigated in the study: the Mediterranean diet and the MIND diet.

A new study from China investigates the complicated, perhaps bidirectional, relationship between Alzheimer’s disease (AD) and malnutrition.

The study concluded that early identification and dietary intervention of people at nutritional risk or who are malnourished may reduce their chances of developing Alzheimer’s.

Once Alzheimer’s appears, individuals often experience an increasing degree of malnutrition as the disease progresses into a downward spiral as adequate nutrition becomes harder and harder to maintain.

As the world’s population ages, the rate of new cases of age-related dementia has declined in many countries, according to the Lancet Commission’s 2020 report. The report observed that improvements in nutrition, education, healthcare, and lifestyle choices are driving this trend.

The Commission estimated that 12 modifiable factors account for 40% of dementias globally.

These include “less education, hypertension, hearing impairment, smoking, obesity, depression, physical inactivity, diabetes, and low social contact.” The good news is that these are modifiable factors.

Previous research suggests that in people with mild cognitive impairment (MCI), a significant reduction of body mass index (BMI) may be an early indicator of cognitive decline. Another study found that, at each stage of Alzheimer’s, malnutrition becomes more pronounced as evidenced by lower weight, BMI, and lean fat mass, and a higher degree of fat mass.

The new observational study involved 266 individuals in China. Of these, 73 people recruited from the general population were assessed as cognitively healthy. The remainder of the participants were enrolled at the Center for Cognitive Neurology at Beijing Tiantan Hospital. Of these people, 72 had mild cognitive impairment due to Alzheimer’s (AD-MCI), and 121 people had dementia due to Alzheimer’s (AD-D).

The researchers took veinous blood samples from the participants and performed detailed body measurements.

The study is published in Frontiers in Nutrition.

Researchers ranked the quality of study participant’s diets according to their adherence to the Mediterranean (MED) diet and MIND (Mediterranean-DASH diet intervention for neurodegenerative delay) diet. Generally, there was no statistically significant difference in diet scores between the three groups. However, scores were slightly lower for people with AD-Dthan AD-MCI and normal cognition groups.

The study does not report the specific foods that earned participants their rankings.

Neuroscientist Dr. Scott Kaiser, who was not involved in the study, asked if participants earned their scores “on green leafy vegetables, or did they get their points on nuts, or did they get them on olive oil, or did they get them on fish — and what kind of fish?” These, he said, “would all make a big difference.”

“Nutritional studies are really hard to do and clearly there’s a need for more randomized, prospective trials,” he added.

A lower BMI value, smaller calf and hip circumferences, and lower scores in the Mini Nutritional Assessment and Geriatric Nutritional Risk Index scores were associated with Alzheimer’s, as were lower levels of total protein, albumin, globulin, and apolipoprotein A1.

The most accurate predictor of Alzheimer’s was a combination of total protein and albumin levels, combined with calf circumference.

The MNA score was the clearest indicator of the line between Alzheimer’s mild cognitive impairment (AD-MCI) and Alzheimer’s full dementia (AD-D).

Although not discussed in this research, Dr. Kaiser pointed out “a fascinating area of study is the impact of an altered microbiome and how it might impact nutrient uptake and energy balance and factors that impact brain health.”

People who have Alzheimer’s often become more and more malnourished as the disease progresses. It may be that Alzheimer’s causes this, or it may simply be that malnutrition — perhaps a factor in the disease’s initial development — is simply making matters worse over time.

According to Dr. Kaiser, there can be both biological mechanisms and social mechanisms driving the greater prevalence of malnutrition with Alzheimer’s.

Michelle Routhenstein, registered dietician and nutritionist at noted, “Individuals with Alzheimer’s disease are more likely to develop malnutrition due to challenges such as difficulty chewing and swallowing, altered taste and smell perception, forgetting to eat, difficulties in meal preparation, and behavioral symptoms like agitation, or lack of interest in eating that affect eating habits and nutritional intake.”

Referring to the social barriers, said Dr. Kaiser, “If somebody can’t feed themselves, if they’re dependent on somebody else for their nutrition, and if their mechanism to indicate hunger is not working properly, then you’ve got a problem.

The MED and MIND diets are related, in that they are both based on the traditional way of eating in areas around the Mediterranean Sea. Both benefit cardiovascular health and weight loss when combined with a physically active lifestyle and social engagement.

Both the MED and MIND diets have also been linked to cognitive health.

The MED diet emphasizes plant foods such as vegetables, fruits, legumes, and whole grains, which are eaten at meals and as snack foods. In addition, the diet calls for healthy fats such as extra virgin olive oil, as well as a moderate consumption of fish, lesser amounts of meat or eggs, and a general avoidance of processed foods.

The MIND diet is based on the Med diet and the DASH (Dietary Approaches to Stop Hypertension) diet. It focuses specifically on supporting cognitive health.

The diet calls for six or more servings per week of, “Leafy greens, leafy greens, leafy greens, to begin with,” said Dr. Kaiser.

Beyond that, said Routhenstein, the diet recommends “berries, nuts, legumes, whole grains, fish, poultry, and olive oil, while avoiding red meats, butter and margarine, cheese, pastries, and fried or fast foods.”

Routhenstein cited some specific foods that strengthen cognitive reserves in people who wish to avoid dementia or Alzheimer’s-related dementia.

“Blueberries, strawberries, and other berries contain antioxidants and flavonoids that may help improve memory and cognitive function,” she said. Dr. Kaiser lauded the value of colorful fruits and vegetables.

In addition, said Routhenstein, “Sesame seeds, and flaxseeds are rich in healthy fats. Polyphenic compounds, like lignans, that support brain health and may help reduce the risk of cognitive decline.”

The MIND diet calls for three or more servings a day of whole grains, such as, she said, “oats, barley, and quinoa [that] provide a steady supply of energy to the brain and contain nutrients like vitamins B6 and folate, which support cognitive function.”

Dr. Kaiser underscored the value of fish in the MIND diet, especially “fish that’s high in these omega-3 fatty acids, DHA specifically, and that’s in cold water fatty fish. Salmon is a great example.”

Routhenstein cautioned, “It is important to note that these diets need to be well-balanced and implemented appropriately to also address potential muscle loss and tone, which may affect Alzheimer’s disease progression.”

She recommended consulting a registered dietician nutritionist to create a dietary plan that is well-suited for each person.

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