The Resulting Variation in Nutrient Intake With the Inclusion of Walnuts in the Diets of Adults at Risk for Type 2 Diabetes: A Randomized, Controlled, Crossover Trial

Can daily consumption of enriched fatty acids diet be effective in improving metabolic syndrome? An attractive paradox for walnut kernel

Imagine consuming a daily diet rich in fatty acids to help treat diseases such as hypertension and obesity. This concept presents an attractive paradox. In particular, consuming walnut kernels is beneficial for treating diseases associated with metabolic syndrome (MetS), including type 2 diabetes, cardiovascular disease, dyslipidemia, and obesity. Different parts of the Juglans regia tree (family Juglandaceae), including its leaves, green husks, bark, and septum, have shown promising effects on pathological conditions related to MetS. The therapeutic advantages of consuming walnut kernels for MetS can be attributed to the presence of polyunsaturated fatty acids and polyphenolic compounds such as juglone and ellagic acid. Diets enriched with walnut kernel have a positive impact on MetS complications by reducing diastolic blood pressure, improving blood lipid profiles, lowering fasting blood sugar levels, and increasing insulin sensitivity. The potential cellular mechanisms responsible for these benefits involve activating the cholesterol hemostasis pathway by inhibiting sterol regulatory element-binding proteins (SREBPs), proprotein convertase subtilisin/kexin type 9 (PCSK9), and cholesteryl ester transfer protein (CETP). Furthermore, other by-products of walnuts, such as leaves and green husks, have also demonstrated effectiveness in managing MetS. These findings highlight the potential of incorporating walnut-based products into our diets as a natural approach to combating MetS and its complications.

Effect of Walnut Supplementation on Dietary Polyphenol Intake and Urinary Polyphenol Excretion in the Walnuts and Healthy Aging Study

Among all tree nuts, walnuts contain the highest total polyphenols by weight. This secondary data analysis examined the effect of daily walnut supplementation on the total dietary polyphenols and subclasses and the urinary excretion of total polyphenols in a free-living elderly population. In this 2-year prospective, randomized intervention trial (ID NCT01634841), the dietary polyphenol intake of participants who added walnuts daily to their diets at 15% of daily energy were compared to those in the control group that consumed a walnut-free diet. Dietary polyphenols and subclasses were estimated from 24 h dietary recalls. Phenolic estimates were derived from Phenol-Explorer database version 3.6. Participants in the walnut group compared to the control group had a higher intake of total polyphenols, flavonoids, flavanols, and phenolic acids in mg/d (IQR): 2480 (1955, 3145) vs. 1897 (1369, 2496); 56 (42,84) vs. 29 (15, 54); 174 (90, 298) vs. 140 (61, 277); and 368 (246, 569) vs. 242 (89, 398), respectively. There was a significant inverse association between dietary flavonoid intake and urine polyphenol excretion; less urinary excretion may imply that some of the polyphenols were eliminated via the gut. Nuts had a significant contribution to the total polyphenols in the diet, suggesting that a single food like walnuts added to habitual diet can increase the polyphenol intake in a Western population.

Effect of Walnut Predinner Snack on Mealtime Hunger and Nutrient Intake Among University Students

Freshman-15 is a phenomenon of first-year university students resulting in weight gain partly due to new cafeteria eating patterns and stress. This study determined if a premeal walnut snack alters planned eating behavior and mealtime nutrient intake during a subsequent buffet-model meal. Healthy university students (n = 36; 18.1 ± 0.5 years; body mass index: 23.6 ± 3.9) received three treatments (90 min premeal) in randomized order on 3 consecutive days: (1) snack of 190 Cal (1 oz) of walnuts (WS), (2) snack of 190 Cal of gummy candy (GS), or (3) no snack (NS; control) before a standard cafeteria dinner (1760 Cal). Visual analog scale (VAS) surveys were administered before and after dinner, and caloric intake was determined. Premeal VAS desire to eat was lower after WS and GS than NS, whereas the sense of hunger and sense of fullness were higher after WS and GS compared with NS. Postmeal VAS was not different between treatments. Mealtime calories, total fat, saturated fat, cholesterol, protein, sodium, fiber, and sugar consumed after WS were significantly less than NS. Total fat and sodium consumed after GS did not significantly differ from NS. Mealtime total fat, sodium, and fiber for WS were significantly less than GC, and a trend was observed for total calories. Differences in calorie intake were not observed between treatments when snack calories were included as part of the mealtime caloric intake. These findings could be helpful for promoting WS and to a lesser degree GS for increased satiety before meals possibly leading to reduced food intake during dinner by university students.