March 2016 Issue
The Wonders of Nuts and Seeds
By Carrie Dennett, MPH, RDN, CD
Vol. 18 No. 3 P. 22
Learn about their health benefits and creative ways to incorporate them into clients' favorite meals and snacks.
Nuts and seeds have been part of the human diet since Paleolithic times. A few nuts, such as almonds and walnuts, and seeds, namely flax and chia, get most of the glory, but the fact is each nut and seed brings something beneficial to the table. While exact nutrient compositions vary, nuts and seeds are rich sources of heart-healthy fats, fiber, plant protein, essential vitamins and minerals, and other bioactive compounds, including an array of phytochemicals that appear to have antioxidant and anti-inflammatory properties.
Health Benefits of Nuts
A wealth of data from prospective observational studies and clinical trials suggest that tree nut consumption reduces the risk of several chronic diseases, including cardiovascular disease (CVD), type 2 diabetes, and some forms of cancer. Moreover, there may be benefits for cognitive health. Adding support to these findings is research suggesting that incorporating tree nuts in the diet lowers the risk of conditions that contribute to disease, such as hypertension, high cholesterol, insulin resistance, abdominal obesity, endothelial dysfunction, oxidative stress, and inflammation.1
Various components of nuts, such as heart-healthy monounsaturated and polyunsaturated fats, plant-based protein, fiber, vitamins, minerals, and phytochemicals may work together to offer protection against oxidation, inflammation, cancer, and CVD.2
Recent findings from the PREDIMED trial suggest that a Mediterranean diet that includes one serving of nuts per day protects against heart attack, stroke, or death from other cardiovascular causes in people at high risk due to type 2 diabetes or metabolic syndrome.3 PREDIMED data also suggest that eating more than three servings of nuts per week reduces risk of death from all causes, especially if also following a Mediterranean diet. Subjects who frequently consumed both total nuts and walnuts had a lower rate of death from cancer.4
Data from the Nurses' Health Study and the Health Professionals Follow-up Study also suggest a reduction in total mortality with regular nut consumption. The greatest protection appeared to be from deaths due to cancer, heart disease, and respiratory disease.1,5 In a 15-year prospective study of almost 3,000 subjects published last year, total nut consumption was associated with a decreased risk of overall and vascular-disease mortality, particularly in women.6 A study published last year found similar results among Americans of African and European descent who were in a low socioeconomic bracket, as well as Chinese individuals living in China. This study was notable because most research to date has been among individuals of European descent, especially those of high socioeconomic status.7
Recent meta-analyses have supported a connection between nut consumption and reduced risk of hypertension and heart disease but not type 2 diabetes.8-10 Results from a recent meta-analysis of 354,933 subjects also suggest a dose-dependent protection against overall mortality, including death from CVD and cancer, with the greatest benefit among subjects eating one serving per day.11
The evidence is substantial enough that dietary guidelines in the United States, Canada, and other countries recommend including nuts as part of a healthful diet, and the FDA allows qualified health claims for nuts for the reduction of heart disease. The FDA concluded in 2003 that a 1.5-oz (43 g) serving per day of most nuts as part of a diet low in saturated fat and cholesterol "may reduce the risk of heart disease" and in 2004 that 1.5-oz serving per day of walnuts as part of an isocaloric diet low in saturated fat and cholesterol "may reduce the risk of coronary heart disease."12
Nuts, Calories, and Body Weight
Although nuts and seeds are energy-dense foods, cross-sectional and observational studies have found an inverse association between tree nuts and BMI or weight gain.13,14 National Health and Nutrition Examination Survey (NHANES) data from 2005 through 2010 show that individuals who ate at least 1/4 oz per day of tree nuts had lower weight, BMI, and waist circumference than those who didn't eat nuts.13 This may be because nuts are satiating and some of the calories in nuts are inefficiently absorbed.13
Interestingly, only 6.8% of the NHANES study population consumed tree nuts,13 and calories could be a barrier to increased intake. However, recent studies have discovered that whole walnuts, almonds, and pistachios all have fewer calories than once thought. Almonds have 32% fewer calories, pistachios have 5% fewer calories, and, most recently, walnuts were found to have 21% fewer calories.14-16
"The potential for using this method to investigate the calorie content of walnuts is intriguing," says David J. Baer, PhD, supervisory research physiologist in the Food Components and Health Laboratory at the USDA's Agricultural Research Service. "Given the potential health benefits of consuming walnuts, including the reduced risk for cardiovascular disease, it's worthwhile to understand the calorie content of walnuts in the human diet and potentially reduce the barriers to their consumption."
Even though nut consumption is associated with a healthy BMI, nuts and seeds are energy dense, so patients should be mindful of portion sizes. While the number of nuts per serving varies by type, a typical serving is 1 oz or about 1/4 cup or a small handful (palm of the hand only). Chere Bork, MS, RDN, owner of Savor Your Life Today, Inc (cherebork.com), keeps a 1/4-cup measure by her bag of nuts. Maggie Moon, MS, RDN, author of The Elimination Diet Workbook, keeps measured snack packs of almonds and pistachios in her desk, gym bag, and purse "so that I always have a healthful snack on hand."
Reaping the Rewards
Because nuts and seeds are complex whole foods that vary—sometimes substantially—in their nutrient composition, it may be the interaction between the vitamins, minerals, fatty and amino acids, fiber, and phytochemicals (carotenoids, flavonoids, polyphenols, and phytosterols) that contribute to health. Rather than focus on one nut or seed, encourage clients to include a variety in their diet.2
"I encourage my patients to try a new nut or seed toasted, such as pepitas (pumpkin seeds) or hazelnuts to add to salads, oatmeal, pilafs, quinoa, or other ancient grain dishes," says Judy Simon, MS, RDN, CD, CHES, of Mind Body Nutrition, PLLC in Bellevue, Washington. "They add a nice flavor, texture, and big nutrition boost of nutrition."
Oakland, California-based Jessica Jones, MS, RD, founder of Jessica Jones Nutrition (jessicajonesnutrition.com), says her favorite place to get a dose of nuts and seeds is in a morning smoothie. "Every morning I toss in a spoonful of pumpkin seeds, hemp seeds, and chia seeds to boost my protein, fiber, and omega-3 intake."
Robin Plotkin, RD, LD, the Dallas-based cofounder of blogbrulee.com and CEO and founder of RobinsBite, Inc, points out that nuts and seeds always have a place in a DIY trail mix recipe. "Along with your standard ingredients, toss in pumpkin seeds, sunflower seeds, or flaxseeds—and/or chopped almonds, pistachios, walnuts, or pecans," she says. "Or, if using a prepared trail mix or granola that doesn't include nuts or seeds, add in a tablespoon of your favorite for extra crunch and added nutrition."
The following are some additional highlights of the nutrient content of nuts and seeds and dietitians' favorite tips:
• Almonds are high in monounsaturated fats, which may explain their association with lower LDL cholesterol levels and reduced heart disease risk. The antioxidant function of the vitamin E (37% DV in 1 oz) in almonds along with their magnesium and potassium also may play a role in cardiovascular health. One study found that almonds may reduce LDL as much as statins.17 "For my chocolate lovers, I recommend mixing a tablespoon of almonds with a tablespoon or two of dark chocolate chips for a satisfying, crunchy snack," Jones says.
• Brazil and cashew nuts: Technically a seed, 1 oz of Brazil nuts contains a whopping 767% DV for selenium. That's over the Tolerable Upper Intake Level of 400 mcg. But eating two Brazil nuts per day has been shown to be an effective way to increase blood levels of this antioxidant mineral healthfully.18 Cashews are lower in fat than most nuts and contain anacardic acid, which may improve insulin sensitivity and help prevent chronic inflammation.19,20
• Chia, flax, and hemp seeds: Flaxseeds are an excellent source of the plant-based omega-3 alpha-linolenic acid, but chia seeds are close rivals. Chia seeds win for fiber content (10 g per oz), while hemp wins for protein (9 g per oz). Chia seeds contain respectable amounts of calcium and other minerals important for bone health, as well as several antioxidants. Numerous studies have suggested that flaxseeds have cardiovascular benefits and possibly cancer-preventive effects.21,22 Ground flaxseeds are more digestible than whole, but they have a short shelf life, about six to 16 weeks in the refrigerator or longer term in the freezer. For maximum freshness, buy whole flaxseeds and grind as needed in a clean coffee grinder.
Connecticut-based nutrition consultant Beth Rosen, MS, RD, CDN, owner of Goodness Gracious Living (goodnessgraciousliving.com), refuels with homemade energy bites: "In a bowl, combine 1 cup oats, 1/2 cup unsweetened peanut butter, 1/4 cup chia seeds, 1/4 cup ground flaxseeds, 1/4 cup chopped dried cherries (or your favorite add-in), and 1/3 cup pure maple syrup. Use a tablespoon of the mixture and roll into balls, placing them on a cookie sheet. Freeze for an hour and store either in the freezer or refrigerator for an easy, on-the-run snack powered by nuts and seeds."
• Peanuts: Technically a legume, peanuts pack more protein per ounce than tree nuts. New Jersey-based Lauren Harris-Pincus, MS, RDN, owner of Nutrition Starring You (nutritionstarringyou.com), touts the particular benefits of powdered peanut butter, also sold as peanut flour. "With only 45 calories per two-tablespoon serving, you get 5 g of plant-based protein for about one-fourth of the calories of regular peanut butter. Stir it into oatmeal, yogurt, overnight oats, smoothies, protein shakes, muffin batter, salad dressings, and marinades, or mix it with water to create a dip for apples."
• Pecans contain multiple forms of vitamin E and are especially rich in gamma-tocopherol, which has been shown to inhibit oxidation of LDL cholesterol.23,24 Oxidized LDL contributes to inflammation in the arteries and is a risk factor for CVD. Pecans also have the highest polyphenol and flavonoid content of the tree nuts.25
• Pistachios: Two studies have shown that eating in-shell pistachios enhances feelings of fullness and satisfaction while reducing caloric intake. When eating in-shell pistachios, study subjects consumed about 40% fewer calories compared with pistachio kernels.26,27 Pistachios have the second highest polyphenol and flavonoid content of the tree nuts.25 Bork likes to toast them and toss them on curries.
• Pumpkin seeds contain small amounts of several forms of vitamin E, and research suggests there's a health benefit to consuming vitamin E in all of its different forms.24 They also contain a unique blend of other antioxidant nutrients.
• Sesame seeds are especially rich in cholesterol-lowering phytosterols.28 Sesame paste (tahini) is an essential ingredient in traditional hummus. Allergies to sesame seeds and other edible seeds are uncommon, but sesame seed allergies are increasing, especially among people allergic to peanuts or certain tree nuts, possibly due to increased exposure.29
• Sunflower seeds are rich in the powerful antioxidant pair vitamin E and selenium. A 1-oz serving alone contains almost one-half the DV of vitamin E. They're noteworthy for their phytosterol, protein, and fiber content. Carolyn Zisman, MS, RDN, a dietitian at Lockheed Martin Corporation in Bethesda, Maryland, says she adds sunflower seeds to many dishes. "They add a nice nutty flavor, lovely crunch, protein, and wealth of nutrients." She says she enjoys throwing sunflower seeds on slaw salads with oil and vinegar, on spaghetti squash with coconut oil and seasoning, on spiralized zucchini with oil and grape tomatoes, and on oatmeal.
• Walnuts are another excellent source of plant-based omega-3 fatty acids. Walnuts also boast the highest antioxidant content of the tree nuts, followed by pecans and cashew nuts.30,31 This makes walnuts one of the best nuts for anti-inflammatory benefits. Like pecans, walnuts are unusually rich in the gamma-tocopherol form of vitamin E.24 It's not for nothing that walnuts are shaped like a brain. Walnut consumption among NHANES subjects is positively associated with cognitive function in both younger and older adults.32 They're a natural source of melatonin, which is critical in the regulation of sleep, circadian (daily) rhythms, and may play a role in walnuts' anticancer benefits.33
— Carrie Dennett, MPH, RDN, CD, is the nutrition columnist for The Seattle Times and speaks frequently on nutrition-related topics. She also provides nutrition counseling via the Menu for Change program in Seattle.
Chewy Walnut Trail Bars
Baked ahead of time, these nutrition-packed walnut trail bars are the perfect snack for long trips, hikes, or even commutes to work. To reduce the sugar content and calories, omit the chocolate chips.
Makes 24 bars
3 cups oats, old fashioned, rolled
1/3 cup brown sugar, light, packed
1/4 cup all-purpose flour, unbleached
1 tsp baking soda
1 tsp cinnamon
1 1/2 cups California walnuts, coarsely chopped
1/2 cup cherries or cranberries, dried
1/2 cup chocolate chips
1/2 cup pumpkin seeds
1/2 cup coconut, shredded
1/4 cup sesame seeds
1/2 cup apricots, dried
1/2 cup butter, cut into small pieces
1/2 cup honey
1. Preheat oven to 325° F. In bowl, whisk together oats, brown sugar, flour, baking soda, and cinnamon. Stir in walnuts, cherries, chocolate chips, pumpkin seeds, coconut, and sesame seeds; set aside.
2. In food processor, process apricots until broken up, about one minute. Add butter and process until a paste forms, about one minute. With motor running, pour in honey until well blended. Fold into oat mixture until well combined. Pat evenly into a parchment-lined 9 X 13-in baking pan.
3. Bake in the center of oven until golden, about 30 minutes. Transfer to rack to cool completely.
4. Cut into bars (2 X 12 rows or 8 X 3 rows).
— Recipe courtesy of The California Walnut Board.
Nutrient Analysis per serving:
Calories: 230; Total fat: 13 g; Sat fat: 5 g; Trans fat: 0 g; Cholesterol: 10 mg; Sodium: 60 mg; Total carbohydrate: 26 g; Dietary fiber: 3 g; Sugar: 13 g; Protein: 4 g
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