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Ask the Bridge
Is
there a diet that promotes brain health?
“Scientists agree that memory loss often accompanies aging -- one
estimate is that 40 percent of people over the age of 60 experience some
memory loss,” says Roberta Durschlag, a clinical assistant professor
of health sciences at Sargent College of Health and Rehabilitation Sciences.
“However, the realization that many elderly don’t experience
this has led scientists to explore factors that may protect against this
loss. In this regard, nutritional factors have been considered.
“Supplementation with the B vitamins -- folate, B6, and B12 -- has
been suggested to prevent memory loss. This is based on the finding that
deficiencies of these vitamins cause an increase in the blood level of
the chemical homocysteine; in some studies, elevated homocysteine has
been associated with poor recall. There thus exists the exciting possibility
of preventing or treating memory loss with simple vitamin supplementation.
“These studies need to be viewed with caution, as others have found
no association between homocysteine status and cognitive functioning.
Further, no studies have shown that vitamin supplementation can actually
prevent or treat memory loss.
“Antioxidants have also been postulated as preventing the memory
decline that accompanies aging. Dietary antioxidants include vitamins
C and E and the vitamin A precursor beta-carotene. Studies that examined
the association between these antioxidants and memory have been inconsistent;
some have found associations, while others have not. One promising trial,
which was performed on patients with memory impairment, showed supplementation
with large doses of vitamin E slowed the progression of decline. However,
the results of an unrelated study on supplementing with large doses of
vitamin E found that it interferes with some prescription drugs.
“This latter finding emphasizes that when vitamins are supplemented
in large quantities, they are consumed as drugs rather than as vitamins.
Although prescription drugs undergo rigorous testing, high doses of vitamins
do not and side effects are certainly possible.
“Herbs and other types of supplements have also been suggested to
stave off memory loss. As with high-dose vitamin supplementation, no government
testing is required on herbs or supplements to demonstrate their effectiveness
or assess their safety.
“Three supplements that have made claims relating to memory are
DHA, phosphatidylserine, and ginkgo biloba. Well-designed clinical trials
to test the effectiveness of DHA in humans are not available. Trials of
ginkgo biloba have been inconsistent, but even in those where any effect
was seen it was very small. Early studies of phosphatidylserine were promising
but used phosphatidylserine derived from cow brains. As awareness of mad
cow disease increased, trials with soy-derived phosphatidylserine were
implemented. That research is still in the very early stages.
“Although these nutritional strategies are preliminary and controversial,
others are not. Chronic diseases such as heart disease, vascular disease,
high blood pressure, and diabetes can impede memory. Nutritional strategies
for preventing and managing these diseases include maintaining a healthy
weight, eating fruits (two to four servings daily), vegetables (three
to five servings daily), whole grains (six to eleven servings daily),
and low-fat dairy products (two to three servings daily). Beef, poultry,
fish, and beans should be low in fat and limited to two to three servings
a day. Maximum sodium intake should be 2400 mg a day. Finally, since alcohol
is known to damage the brain, men should consume not more than two and
women one serving of alcohol a day.”
"Ask the Bridge" welcomes readers' questions. E-mail bridge@bu.edu or write to "Ask the Bridge," 10 Lenox Street, Brookline, MA 02446.
25
October 2002
Boston University
Office of University Relations