Food and Nutrient Displacement by Walnut Supplementation in a Randomized Crossover Study

Association of nut consumption with insulin resistance and blood lipid profile in Spanish university students

AIMS

To examine whether nut consumption was associated with insulin resistance and blood lipid parameters in a sample of young healthy adults.

MATERIAL AND METHODS

A cross-sectional study was conducted involving 306 first-year students (aged 18-30 years) from the University of Castilla-La Mancha, Spain. Biochemical variables related to insulin resistance and blood lipid profile (glucose, insulin, HbA1c, total cholesterol (total-c), LDL-c, HDL-c, and triglycerides) were determined from morning fasting blood samples. Nut consumption was estimated using a 137-item Food-Frequency Questionnaire. The associations of walnuts, other nuts and total nut intakes with insulin resistance and lipid profile variables and surrogates were assessed by linear regression analysis. Differences in insulin resistance and lipid profiles between participants meeting or not meeting the nut consumption recommendations were examined by analysis of covariance (ANCOVA). Logistic regressions were used to analyze the likelihood of having higher levels of blood lipids or insulin resistance in participants who met or did not meet the recommended intake of nuts.

RESULTS

There was no association found between nut consumption, whether walnuts or other nut varieties, and insulin resistance and lipid profile variables. Additionally, there were no significant differences in insulin resistance or blood lipid profile variables between university students meeting or not meeting nut consumption recommendations. Finally, stratified analyses based on sex were consistent and did not substantially modify our estimates in the fully adjusted models.

CONCLUSIONS

In conclusion, our results suggest that walnuts, other types of nuts, and total nut consumption did not adversely influence metabolic or lipid profile variables among healthy young adults. Although nuts are recommended among healthy dietary patterns, our findings showed that nut consumption has a null effect on the cardiometabolic risk parameters explored in young healthy adults.

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.

A comprehensive review on ethnobotanical, medicinal and nutritional potential of walnut (Juglans regia L.)

Juglans regia L. commonly known as walnut is used as the most extensive and economical tree in the world. This review aims to study the ethnomedicinal, phytochemical and pharmacological potential of walnut. The literature has been collected from different online sources like science Direct, Scopus, ResearchGate, Google Scholar, PubMed, etc. based on inclusion and exclusion criteria. An ethnomedicinal survey has also been conducted to document the traditional knowledge and uses of walnut among the local peoples of the Union Territory of Jammu and Kashmir. On surveying the local peoples in the different major walnut-producing areas, it has been followed that the walnut is locally used as a medicinal, nutritional, and commercial plant to treat common diseases and disorders in the locality. The survey has been conducted first time in the area and no study has been reported till now in the Jammu Division while some work has been reported in the Kashmir Division. Among the many bioactive compounds present in various plant parts, Juglone has been reported a significant anti-cancer compound in treating deadly cancer. This systematic review describes the significant knowledge and traditional information collected on ethnomedicinal uses, phytochemistry, habitat, macro-morphology, area of distribution, and pharmacological importance.