Answering client questions about nutrition and prevention.
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 diet.
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 buster.
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.