Alzheimer’s and Diet
Answering client questions about nutrition and prevention.
Aug 15, 2015
It’s never too early to talk about Alzheimer’s disease—even for a
nonmorning person like me. On a misty March morning in New York’s
financial district, I rushed across traffic and made it to the 8:00 am
continental breakfast just in time for the “Role of Nutrition in
Dementia Prevention and Management” conference, which was buzzing with
the world’s foremost nutrition epidemiologists and Alzheimer’s experts.
With new research from twin studies suggesting that modifiable lifestyle
factors could be responsible for 20%–40% of Alzheimer’s disease risk,
primary prevention through sound nutrition was a hot conference topic
(Poirier et al. 2014). As I enjoyed my berry parfait, I heard evidence
that Alzheimer’s may start in the brain 20–30 years before symptoms
appear (Ossenkoppele et al. 2015).
Prevalence of Alzheimer’s and related dementias is rapidly rising and
could reach 135 million worldwide by 2050, according to Alzheimer’s
Disease International (ADI 2013). What should we be telling our clients
who have a family history or are trying to cut their risk? Read on for
current scientific evidence on dietary patterns, dietary fat, and
vitamins that may just help ward off dementia.
Certain dietary patterns appear to protect against cognitive decline.
Historically, the Mediterranean diet and the Dietary Approaches to Stop
Hypertension (DASH) diet have been widely studied for heart disease
prevention, but more recent research has also focused on their ability
to decrease dementia risk. In a prospective study in the American
Journal of Clinical Nutrition, both diets were associated with a
decrease in cognitive decline over an 11-year period (Wengreen et al.
2013). Higher adherence to the Mediterranean diet has also been
associated with lower levels of inflammatory markers and therefore may
decrease oxidative stress in the brain (Singh et al. 2014).
The NYC conference included results of a prospective study evaluating a
new dietary pattern developed to focus on brain health. After reviewing
comprehensive evidence, Martha Clare Morris, ScD, of Rush University
created the Mediterranean-DASH Intervention for Neurodegenerative
Delay—also known as the MIND diet—which uses a three-pronged approach:
- emphasizing plant-based, whole foods, and olive oil as the primary oil
- limiting animal products and saturated fat
promoting one fish meal a week because of the strong link between
omega-3 and brain health (Morris et al. 2015a).
At the conference, Morris presented the impressive results of her
prospective study. She followed 923 people, aged 58–98, over 4.5 years
to see who would develop dementia, and then she compared how closely
they followed the MIND, Mediterranean or DASH diets based on scales of
adherence. The MIND diet was associated with a 53% risk reduction for
those with the strictest diet adherence and a 35% reduced risk for those
with moderate diet adherence. The DASH and Mediterranean diets elicited
significant reductions in cognitive decline only with the highest level
of adherence (Morris et al. 2015a). This is a notable difference: Always
adhering strictly to a new way of eating isn’t easy, so it’s good news
to see that moderate adherence to the MIND diet might be protective.
The MIND diet’s specific recommendations (see the sidebar “MIND Diet
Components”) may explain its effectiveness. As Morris notes, animal
research suggests that leafy greens and berries, in particular, are
protective of the aging brain, and therefore the MIND diet recommends at
least two servings of flavonoid-rich berries and a minimum of six
servings of vitamin-rich leafy greens per week.
The DASH and Mediterranean diets, however, recommend eating a lot of
nonspecific vegetables and fruit, which are still beneficial but may not
be as imperative for brain health. According to Morris, evidence from
the MIND study shows that those who ate the most leafy greens were 11
years younger in cognitive age than those who ate the least. Clients
would benefit from including kale, mustard greens, romaine lettuce,
spinach and other leafy greens on their weekly menus.
Dietary Fat and the Brain
Richard Isaacson, MD, another speaker at the conference, is an
Alzheimer’s prevention doctor who works in New York City. In his talk,
he noted that he advises clients to limit their intake of saturated fat,
which often improves their cholesterol panels. A study exploring
dementia risk in middle-aged people found a 57% higher risk of
developing Alzheimer’s three decades later in those whose cholesterol
levels were over 240 mg/dL (which is considered high) compared with
those whose levels were normal ( 200 mg/dL) (Solomon et al. 2009).
The Therapeutic Lifestyle Changes (TLC) Diet, which can reduce
cholesterol, recommends that no more than 7% of calories come from
saturated fat (NHLBI 2015). Saturated fat mostly comes from animal
sources such as red meat, cheeses and high-fat dairy. Processed,
high-fat grain products are also significant sources. I advise clients
to include more lean meats over red meats, choose fat-free dairy and
limit cheese, which is a large source of saturated fat in the American
The ratio of polyunsaturated fat to saturated fat may also be an
important consideration for long-term brain health. In the Chicago
Health and Aging Project, which examined dietary fat and dementia risk,
those with the highest intake ratio of unsaturated to saturated fat had
a 70% lower risk of developing dementia over 4 years. A decreased risk
was also found with higher intake of monounsaturated fat, which is found
in nuts, seeds, avocado and olive oil (Morris & Tangney 2014).
Replacing a high-saturated-fat steak with a fatty fish such as herring,
halibut, salmon or mackerel could help stave off dementia by increasing
important levels of two essential fatty acids: DHA and EPA. If clients
don’t eat fish, they can obtain another omega-3, alpha-linolenic
acid—which is converted to DHA in small amounts—from ground flax seeds,
chia seeds and walnuts.
Water-soluble B vitamins play a large role in carbohydrate metabolism
and help fuel the brain, which is why B-vitamin deficiencies may
increase the rate of cognitive decline. Deficiency in vitamin B12, which
helps maintain healthy brain and nerve cells, is related to elevated
levels of homocysteine, an inflammatory neurotoxin and independent risk
factor for Alzheimer’s (Seshadri et al. 2002). Deficiency increases with
age due to changes in stomach acid that make it more difficult to absorb
B12 from food sources, such as meats and dairy. Fortified foods and
supplements are better absorbed. At least 6% of people older than 60 are
deficient in vitamin B12, and 20% have very low levels, so having levels
checked by a physician is a smart move (Allen 2009).
Folate also plays a role in homocysteine metabolism. Low levels of the
vitamin are associated with neural-tube defects in newborns and have
also been associated with poorer memory recall, but experts are hesitant
to recommend folate supplementation for brain health. Using NHANES data
from 2007, researchers found the combination of high folate levels with
low B12 levels might actually increase the risk of cognitive impairment.
I recommend food sources to clients to help them meet the folate RDA of
400 micrograms per day (Morris 2012). Folate-rich foods include leafy
green vegetables, such as broccoli, kale and spinach; beans and peas;
citrus fruits; and cantaloupe.
There is conflicting evidence for the role of antioxidants and dementia,
but it is hypothesized that vitamins E and C may work in concert to help
reverse age-related neuronal decline by protecting the brain from
free-radical damage. Vitamin E is fat soluble and found in whole grains,
nuts, seeds and oils, and it is the most powerful antioxidant in the
diet. Water-soluble vitamin C is less potent, but it acts to restore
vitamin E to its active form.
Epidemiologic studies associate higher vitamin E serum levels with
reductions in cognitive decline in older adults (Mangialasche et al.
2013), but not all forms of vitamin E are created equal. The vitamin E
form found in food, gamma-tocopherol, appears to offer the best
protection against oxidative stress, while the form found in
supplements, alpha-tocopherol, has shown no benefit in controlled
trials. There is some evidence that the supplemental form in high doses
may decrease the food form’s effectiveness (Morris et al. 2015b).
According to NHANES data, 93% of the population is deficient in vitamin
E from food sources (Fulgoni et al. 2011), so adding wheat germ to
cereal and a handful of nuts to leafy green salads is more advisable
than taking supplements to meet vitamin E needs.
Vitamin D and Multivitamins
Vitamin D is the class valedictorian of the supplement aisle and with
good reason. Research is finding a multitude of benefits from adequate
vitamin D status, but food sources of the vitamin are scarce. Animal
studies have demonstrated that supplementation with vitamin D may
reverse age-related inflammatory changes in the brain by enhancing
growth of the hippocampus, the area of the brain most affected by
Alzheimer’s (Moore et al. 2005). Results from an intervention study of
older adults indicate that supplementation with 800 IU of vitamin D
daily helped to improve cognitive function over a 16-month period
(Annweiler et al. 2012a). In another study of dietary vitamin D intake,
women who consumed 10 mcg more of vitamin D per day, the amount found in
one 4-ounce serving of cooked salmon, had a significantly lower risk of
developing dementia after a 7-year period than study subjects who
consumed less vitamin D (Annweiler et al. 2012b).
In a recent international recommendation article on vitamin D and
cognition, consensus was that low vitamin D levels should be checked and
supplemented, and food sources high in vitamin D—such as salmon,
fortified orange juice and low-fat dairy—should be frequently included
in the diet (Annweiler et al. 2015). Encouraging clients to have their
levels checked is a good practice.
When it comes to multivitamin use, there is no clear answer. Higher
intake of copper from supplements has been correlated with increased
risk of dementia equivalent to up to 19 years of aging. Excessive intake
of iron may also contribute to cognitive problems. Multivitamins should
contain only vitamins and no minerals to decrease cognitive decline
(Barnard et al. 2014).
Keeping Clients Informed
As experts continue to work hard to discover new evidence about
Alzheimer’s, we should inform our clients about current research while
keeping in mind that our understanding of primary prevention is
evolving. We don’t yet have all the answers, but following a MIND,
Mediterranean or DASH-type dietary pattern that emphasizes berries,
leafy greens, and vitamin- and mineral-rich whole foods, and having a
physician check your levels of vitamin B12 and D shouldn’t be a brain
Joanna Morris, MS, RDN, LDN, is a wellness-focused dietitian, health
coach and freelance writer in the Baltimore–Washington DC area. Her
health philosophy stresses the importance of a whole-foods, plant-based
diet and a varied fitness regimen that includes a focus on stress
reduction through mind-body work.