Walnuts may be uniquely healthy

walnuts

Would you spend 6 months eating 1/2 cup of walnuts every single day?  It could get old, but that’s what the participants in a recent study did.  The purpose was to assess the potential health benefits on a variety of risk factors for heart disease and diabetes.  The subjects, who were at risk for developing diabetes, were tested for many indicators including weight, blood glucose, cholesterol, blood pressure, endothelial function and a diet quality score called the Healthy Eating Index.  The effect of walnut consumption was compared to diet periods with no nuts eaten at all.

All nuts are healthy in their plain form.  But some nuts are more studied than others, probably thanks to research funding from agricultural trade organizations.  Compared to almonds (another well-studied nut), walnuts have more fat and less carbohydrate and natural sugars.  Bonus points: they have 3 times as much polyunsaturated fat as almonds, and a significant amount of omega-3 fat, in the form of the 18-carbon alpha-linolenic acid (NOTE: Because unsaturated fats are prone to oxidation and rancidity, walnuts should be stored in the refrigerator).

Amount per 100 grams walnuts   almonds
calories             620         580
protein              24 g        21 g
fat                  59 g        50 g
polyunsaturated      36 g        12 g
carbs                9.6 g       22 g

During the walnut-eating part of the study, participants ate about 2 oz per day, about 350 calories and an impressive 33 grams of fat.  Walnut consumption was linked to improved diet quality, lower total and LDL cholesterol and improved endothelial function.  Other disease risk factors, such as fasting blood glucose and blood pressure, did not change significantly.

What is endothelial function and why is it important?

The term refers to the lining of blood vessels.  The vessel walls are made up of endothelial cells, which need to be both strong and flexible to withstand the pressure of blood flow, while also allowing the exchange of molecules between blood and tissues.  Poor endothelial function is linked to plaque accumulation and risk for high blood pressure and stroke.

Calorie Math

Despite those additional calories, body weight did not change significantly during the study, even though study subjects spent 6 months eating walnuts everyday.  That’s 180 days times 350 calories/day, potentially 63,000 extra calories, equivalent to 18 lbs of body fat.  Why didn’t these people gain at least some weight?  One possible explanation comes from another recent study that examined the actual digestibility of walnuts.  Values in standard calorie databases show that they provide about 185 calories/ounce.  But this study found that in fact only 146 calories, on average, were available when people ate walnuts.  Why fewer calories?  Walnuts are not completely digestible in the human gut.  20% of the calories are wasted, perhaps because they are not chewed completely.  Almonds were the subject of a similar study a while ago.

What this study didn’t tell us:

  • Walnuts are better than other nuts for lowering cholesterol and improving endothelial function
  • Walnuts will prevent heart disease and stroke

Whether or not your goal is to improve endothelial function and cholesterol, walnuts are a great food.  They’re convenient, have a rich satisfying flavor,  and are low sugar and low sodium, with significant protein.  If the idea of eating 1/2 cup every day sounds boring, there are plenty of other ways to include walnuts in your diet:

  • Snacks. Replace your sugary “energy” bar or candy or chips with a handful of walnuts.
  • Breakfast: Sprinkle chopped walnuts on oatmeal or cold cereal, such as granola
  • Sandwiches: Add chopped walnuts to a wrap or sandwich for crunch and flavor
  • Pasta: Add walnuts to marinara sauce or pasta salad
  • Breads and muffins: Add chopped walnuts to your favorite baked foods, from breads to muffins to cookies
  • Salads: Walnut pieces go great on tossed salad, healthier than croutons
  • Yogurt: Mix chopped walnuts into yogurt for breakfast, lunch or snacks
  • Grains: Use chopped walnuts for grain casserole topping, or add to salads made with grains

And finally: use whole walnuts on your holiday or winter table centerpiece.  Then when the meal is over, get out the nut crackers and munch on walnuts for dessert.

Copyright: All content © 2010-2018 Nutrition Strategy Advisors LLC. Photographs © Donna P Feldman, unless otherwise attributed. Reproduction or use without permission is prohibited.