Pamela Wolfe

Low circulating adiponectin levels may contribute to higher diabetes risk among Mexican Americans (MA) compared to non-Latino whites (NLW). Our objective was to determine if among young healthy adult MAs have lower adiponectin than NLWs, independent of differences in adiposity. In addition, we explored associations between adiponectin and diet. This was an observational, cross-sectional study of healthy MA and NLW adults living in Colorado (U.S.A.). We measured plasma total adiponectin, adiposity (BMI, and visceral adipose tissue), insulin sensitivity (IVGTT), and self-reported dietary intake in 43 MA and NLW adults. Mean adiponectin levels were 40% lower among MA than NLW (5.8 ± 3.3 vs. 10.7 ± 4.2 µg/mL, p = 0.0003), and this difference persisted after controlling for age, sex, BMI, and visceral adiposity. Lower adiponectin in MA was associated with lower insulin sensitivity (R² = 0.42, p < 0.01). Lower adiponectin was also associated with higher dietary glycemic index, lower intake of vegetables, higher intake of trans fat, and higher intake of grains. Our findings confirm that ethnic differences in adiponectin reflect differences in insulin sensitivity, but suggest that these are not due to differences in adiposity. Observed associations between adiponectin and diet support the need for future studies exploring the regulation of adiponectin by diet and other environmental factors.

Women who are obese at the time of breast cancer diagnosis have higher overall mortality than normal weight women and some evidence implicates adiponectin and leptin as contributing to prognostic disadvantage. While intentional weight loss is thought to improve prognosis, its impact on these adipokines is unclear. This study compared the pattern of change in plasma leptin and adiponectin in overweight-to-obese post-menopausal breast cancer survivors during weight loss. Given the controversies about what dietary pattern is most appropriate for breast cancer control and regulation of adipokine metabolism, the effect of a low fat versus a low carbohydrate pattern was evaluated using a non-randomized, controlled study design. Anthropometric data and fasted plasma were obtained monthly during the six-month weight loss intervention. While leptin was associated with fat mass, adiponectin was not, and the lack of correlation between leptin and adiponectin concentrations throughout weight loss implies independent mechanisms of regulation. The temporal pattern of change in leptin but not adiponectin was affected by magnitude of weight loss. Dietary pattern was without effect on either adipokine. Mechanisms not directly related to dietary pattern, weight loss, or fat mass appear to play dominant roles in the regulation of circulating levels of these adipokines.

Introduction: Healthy body weight is an important factor for prevention of breast cancerrecurrence. Yet, weight loss and weight gain are not currently included inclinical-practice guidelines for posttreatment of breast cancer. The work reportedaddresses one of the questions that must be considered in recommending weight lossto patients: does it matter what diet plan is used, a question of particularimportance because breast cancer treatment can increase risk for cardiovasculardisease. Methods: Women who completed treatment for breast cancer were enrolled in a nonrandomized,controlled study investigating effects of weight loss achieved by using twodietary patterns at the extremes of macronutrient composition, although both dietarms were equivalent in protein: high fat, low carbohydrate versus low fat, highcarbohydrate. A nonintervention group served as the control arm; women wereassigned to intervention arms based on dietary preferences. During the 6-monthweight-loss program, which was menu and recipe defined, participants had monthlyclinical visits at which anthropometric data were collected and fasting blood wasobtained for safety monitoring for plasma lipid profiles and fasting glucose.Results from 142 participants are reported. Results: Adverse effects on fasting blood lipids or glucose were not observed in eitherdietary arm. A decrease in fasting glucose was observed with progressive weightloss and was greater in participants who lost more weight, but the effect was notstatistically significant, even though it was observed across both diet groups(P = 0.21). Beneficial effects of weight loss on cholesterol (4.7%;P = 0.001), triglycerides (21.8%; P = 0.01), and low-densitylipoprotein (LDL) cholesterol (5.8%; P = 0.06) were observed in bothgroups. For cholesterol (P = 0.07) and LDL cholesterol (P =0.13), greater reduction trends were seen on the low-fat diet pattern; whereas,for triglycerides (P = 0.01) and high-density lipoprotein (HDL)cholesterol (P = 0.08), a decrease or increase, respectively, was greateron the low-carbohydrate diet pattern. Conclusions: Because an individual's dietary preferences can affect dietary adherence andweight-loss success, the lack of evidence of a negative effect of dietary patternon biomarkers associated with cardiovascular risk is an important consideration inthe development of breast cancer practice guidelines for physicians who recommendthat their patients lose weight. Whether dietary pattern affects biomarkers thatpredict long-term survival is a primary question in this ongoing clinicaltrial.

Weight loss in overweight or obese breast cancer patients is associated with an improved prognosis for long term survival. However, it is not clear whether the macronutrient composition of the chosen weight loss dietary plan imparts further prognostic benefit. A study protocol is presented for a dietary intervention to investigate the effects of weight loss dietary patterns that vary markedly in fat and carbohydrate contents on biomarkers of exposure to metabolic processes that may promote tumorigenesis and that are predictive of long term survival. The study will also determine how much weight must be lost for biomarkers to change in a favorable direction.