A new study published in the Journal of Nutrition reveals that walnuts have 21 per cent fewer calories than what is currently assigned by USDA. The study results show that one serving (1 oz.) of walnuts contains 146 calories, not 185, which is 39 calories less than the value currently used. The research was led by Dr David J Baer, supervisory research physiologist at the agricultural research service, United States Department of Agriculture (USDA).
Historically, the calorie value for walnuts was determined using the Atwater factors, which were developed in the late 19th century and calculates metabolisable energy, or energy available to the body, for many foods. Dr Baer’s research found that the metabolisable energy of walnuts was 21 per cent less than that predicted by the Atwater factors.
“Our results could help explain why consumers of walnuts do not typically gain weight,” said Dr Baer. “And given the numerous potential health benefits of consuming walnuts, including reduced risk for cancer, cardiovascular and cognitive diseases, our results could potentially help alleviate any calorie-related concerns consumers might have with incorporating them into their everyday diet.”
Walnuts contain several antioxidants and polyphenols which provide multiple benefits to health. Expanding more on the health benefits of walnuts, Dr H K Chopra, president, Cardiological Society of India, said, “Walnuts are one of the richest sources of Omega-3 fatty acids, with 2.5 gram of alpha-linolenic acid (ALA) per serving. Several studies have suggested that regular consumption of walnuts helps in effective weight management. Any successful weight management plan must include satiety factor and owing to the high fibre content, walnut is undoubtedly the right food to consider if you are into a weight management programme."
Commenting on the research, Naini Setalvad, nutritionist and health consultant, said, "Consuming a diet comprised of walnuts is the key to healthy living. Incorporating walnuts into meals and snacks is a simple, delectable and convenient way to help ensure adequate protein intake, especially among vegetarians. One ounce of walnuts provides four gram of protein, and two gram of fibre. The fibre aspect helps make you feel full, promotes weight management, and can assist in lowering cholesterol and regulating blood glucose levels."
To reach their conclusion, the research team studied 18 healthy adults. Each person was assigned randomly to a sequence of two diets: a controlled American diet without walnuts for a 3-week period, and a controlled diet with 1.5 servings of walnuts (42 gram) for another 3-week period. Total calorie levels were consistent for individual participants across both treatment periods. Administered diets, walnuts, faecal and urine samples were collected and subject to bomb calorimetry, to measure calories, and the resulting data were used to calculate the metabolisable energy of the walnuts.
The study provides insight into the growing body of research supporting the beneficial role walnuts play in weight management. In addition to providing a convenient source of fibre (2 gram per ounce) and protein (4 gram per ounce), walnuts are the only nut that contain a significant source of alpha-linolenic acid (2.5 gram per ounce), a plant-based Omega-3 fatty acid with heart- and brain-health benefits.
