people are often frail and suffer from both functional and cognitive impairment. In addition to overall inadequate food intake, several studies have pointed to more specific nutrients and functional decline.
Dietary patterns and nutritional status associated with healthy ageing
Because we eat foods with a variety of macro‐ and micronutrient profiles together rather than single nutrients in isolation, there has been emerging interest in assessing the relationship between dietary patterns in relation to health. Analytical approaches to the study of dietary patterns include index scores, cluster analysis, and factor analysis (principal component analysis). Cluster analysis forces study participants into groupings based on their dietary intake, assuming that each participant belongs to only one pattern. These ‘clusters’ are then tested in relation to outcomes of interest. Index scores quantify individuals based on their adherence to dietary pattern defined a priori (i.e. MeDi diet, DASH, MIND diet). These index scores are then related to outcomes. Factor analysis (principal component analysis [PCA]) is an unbiased and data‐driven approach to identifying dietary patterns in the study population that are distinct from one another and scoring each individual on each of the patterns outlines with PCA. Then each PCA‐derived dietary pattern is associated with outcomes. Several dietary patterns have been developed in the United States and Europe, and many of them have overlapping similarities (summarized in Table 12.1). These methods can also be applied to biochemical indicators of diet (i.e. nutrient biomarkers) with the added benefit of being objective rather than relying on older adults to recall dietary habits that can introduce forms of information bias (i.e. recall and misclassification bias).46 Nutrient biomarkers can also provide some insight into genetic and non‐genetic (i.e. microbiome) impact regardless of self‐reported intake that may have significance to nutrient availability to target tissues (i.e. brain, bone, muscle).
Table 12.1 Dietary and nutrient biomarker patterns associated with cognitive, bone, and muscle health.
| Nutrients | Foods | Cognitive | Bone | Muscle | |
|---|---|---|---|---|---|
| MIND diet29 | Higher intake of vitamin E, folate, flavonoids, carotenoids, dietary fibre, and monounsaturated fats and lower intake of saturated and trans fatty acids | ≥6 serving/wk green leafy vegetables (kale, collards, greens; spinach; lettuce/tossed salad); ≥1 serving/wk green/red peppers, squash, cooked carrots, raw carrots, broccoli, celery, potatoes, peas or lima beans, potatoes, tomatoes, tomato sauce, string beans, beets, corn, zucchini/summer squash/eggplant, coleslaw, potato salad; ≥2 servings/wk of berries (blueberries, blackberries, strawberries); ≥5 servings/wk nuts (walnuts, almonds); olive oil as primary cooing oil <1 tablespoon/day of butter, margarine; <1 serving/wk of cheese; ≥3 servings/day of whole grains; ≥1 meal/wk non‐fried fish; >3 meals/wk of beans (lentils, soybeans); ≥2 meals/wk poultry (not fried) (chicken, turkey); <4 meals/wk of red meat and products (cheeseburger, hamburger, beef tacos/burritos, hot dogs/sausages, roast beef or ham sandwich, salami, bologna, or other deli meat sandwich, beef [steak, roast] or lamb as main dish, pork or ham as main dish, meatballs or meatloaf); <1 time/wk of fast fried foods (French fries, chicken nuggets) <5 servings/wk of pastries and confectionary (biscuit/roll, pop tarts, cake, snack cakes/Twinkies, Danish/sweet rolls/pastry, doughnuts, cookies, brownies, pie, candy bars, other candy, ice cream, pudding, milkshakes/frappes); 1 glass/day of wine | X29,30 | X31 | |
| DASH diet32 | Higher intake of potassium, magnesium, fibre, calcium, monounsaturated fats and protein; low in saturated fats, cholesterol, and sodium. | ≥5 servings/day of fruits and juices; ≥4 servings/day of vegetables; ≥7 servings/day of grains; 2 servings/day of low‐fat dairy; 1 serving/day regular fat dairy; ≥1 serving/day of nuts, seeds, and legumes; ≤0.5 serving/day beef, pork and ham; 0.5 serving/day of poultry; 0.5 serving/day of fish; 2.5 servings/day fat, oils, and salad dressing; <1 serving/day of snacks and confectionary | X33 | X34–36 | |
| MeDi diet37 | High intake of folate, vitamin E, carotenoids, flavonoids, and other antioxidants, dietary fibre, omega‐3 fatty acids; lower intake of saturated fatty acids | Increased consumption of fruits, vegetables, whole grains, and olive oil; everyday consumption of fermented dairy (with lactic acid bacteria such as lactobacillus), nuts, seeds, herbs or spices, plant‐based protein sources (legumes), and seafood rather than red meat; wine in moderation, and daily consumption of herbal infusions (tea) | X38,39 | X 34,40,41 | X40,42 |
| Oregon Brain Aging Study43 | Higher blood levels of B1, B2, B6, folate, B12, C, D, E, omega‐3 fatty acids, carotenoids (lutein and zeaxanthin) associated with superior cognitive function and MRI measures of brain ageing | Lentils, green leafy vegetables, citrus and peppers, fish | X43 | ||
| Tri‐City Study44 | Higher blood levels of vitamin D, carotenoids, and polyunsaturated fatty acids and lower levels of saturated fats associated with less risk of dementia | Fish and green leafy vegetables | X44 | ||
| Multi‐domain Alzheimer prevention trial45 | Higher blood levels of vitamin D and omega‐3 fatty acids and lower levels of homocysteine | Fish and green leafy vegetables | X45 |
Medi‐DASH, Diet Intervention for Neurodegenerative Delay; DASH, Dietary Approaches to Stop Hypertension; MeDi, Mediterranean style diet.
Dietary patterns associated with healthy cognitive ageing
The wave of ageing elders is also placing many more people at risk for cognitive impairment and dementia. It is estimated that 100 million people will have dementia by 2050, and this will cripple a fragile healthcare system where people live for an additional 8‐20 years after the diagnosis requiring caregivers and family support. Thus, prevention strategies are needed to delay onset and maintain independence in older adults. Nutrition may play a significant role in preventing and even managing dementia, including Alzheimer’s disease. An abundance of evidence supports nutrition for the prevention of age‐related cognitive decline and dementia, but there are few specific recommendations due to inconclusive clinical trial results. There have been several interventions testing single or a few nutrients for the prevention of cognitive decline. These include the homocysteine‐lowering B vitamins (B6, B12, and folate), vitamin E (alpha tocopherol), and the omega‐3 fatty acids (docosahexaenoic acid). Next‐generation clinical trials are underway that are more targeted and comprehensive, offering further hope of recommendations in the future (clinicaltrials.gov: NCT01953705, NCT02817074).
Studies of dietary patterns related to age‐related cognitive impairment