Effects of agave nectar versus sucrose on weight gain, adiposity, blood glucose, insulin, and lipid responses in mice.

Agave nectar is a fructose-rich liquid sweetener derived from a plant, and is often promoted as a low glycemic alternative to refined sugar. However, little scientific research has been conducted in animals or humans to determine its metabolic and/or health effects. The aim of this study was to explore the influence of agave nectar versus sucrose on weight gain, adiposity, fasting plasma blood glucose, insulin, and lipid levels. Eighteen (n=18) male ICR mice (33.8±1.6 g) were divided into two groups (n=6 for agave nectar and n=12 for sucrose) and provided free access to one of two diets of equal energy densities differing only in a portion of the carbohydrate provided. Diets contained 20% carbohydrate (by weight of total diet) from either raw agave nectar or sucrose. Epididymal fat pads were excised, and blood was collected after 34 days. Weight gain (4.3±2.2 vs. 8.4±3.4 g), fat pad weights (0.95±0.54 vs. 1.75±0.66 g), plasma glucose (77.8±12.2 vs. 111.0±27.9 mg/dL), and insulin (0.61±0.29 vs. 1.46±0.81 ng/mL) were significantly lower (P≤.05) for agave nectar-fed mice compared to sucrose-fed mice respectively. No statistically significant differences in total cholesterol or triglycerides were detected. These results suggest that in comparison to sucrose, agave nectar may have a positive influence on weight gain and glucose control. However, more research with a larger sample of animals and/or with human subjects is warranted.

Effects of dark chocolate on azoxymethane-induced colonic aberrant crypt foci.

Epidemiologic evidence supports that diets rich in polyphenols promote health and may delay the onset of colon cancer. Cocoa and chocolate products have some of the highest polyphenolic concentrations compared to other polyphenolic food sources. This study tested the hypothesis that a diet including dark chocolate can protect against colon cancer by inhibiting aberrant crypt foci (ACF) formation, downregulating gene expression of inflammatory mediators, and favorably altering cell kinetics. We also investigated whether bloomed dark chocolate retains the antioxidant capacity and protects against colon cancer. Forty-eight rats received either a diet containing control (no chocolate), regular dark chocolate, or bloomed dark chocolate and were injected subcutaneously with saline or azoxymethane. Relative to control, both regular and bloomed dark chocolate diets lowered the total number of ACF (P = 0.022). Chocolate diet-fed animals downregulated transcription levels of COX-2 (P = 0.035) and RelA (P = 0.045). Both chocolate diets lowered the proliferation index (P = 0.001). These results suggest that a diet including dark chocolate can reduce cell proliferation and some gene expression involving inflammation, which may explain the lower number of early preneoplastic lesions. These results provide new insight on polyphenol-rich chocolate foods and colon cancer prevention.

The protective effects of green tea polyphenols: lipid profile, inflammation, and antioxidant capacity in rats fed an atherogenic diet and dextran sodium sulfate.

Acute and chronic inflammation and dyslipidemia play a critical role in the development of various diseases, including cardiovascular disease. Green tea polyphenols possess potent antioxidative and anti-inflammatory properties that contribute to the beneficial effects on heart health. The present study was carried out to determine if administration of a green tea extract (Polyphenon(®) E [PPE]; Mitsui Norin Co., Ltd., Tokyo, Japan) at 0.2% in the diet reduces cardiovascular risk factors, including dyslipidemia, inflammation, adiposity, and oxidative stress, in rats fed an atherogenic (high fat, cholesterol, and sugar) diet with dextran sodium sulfate (DSS) in drinking water. DSS treatment increased serum total cholesterol, low-density lipoprotein (LDL)-cholesterol, C-reactive proteins (CRP), and markers of liver toxicity and decreased high-density lipoprotein (HDL)-cholesterol significantly. Adding PPE to the atherogenic diet (PPE-diet) was associated with lower total cholesterol and LDL-cholesterol (P<.001) and increased HDL-cholesterol (P=.001). In addition, the PPE-diet was associated with decreased serum CRP concentration (P=.023) and increased total antioxidant capacity (P=.016) and catalase (P=.001) and glutathione peroxidase (P=.050) activities. The PPE-diet significantly lowered epididymal fat pad weight (P=.009). Feeding the PPE-diet also ameliorated some of the DSS-induced lipid, inflammatory, and oxidative symptoms. In summary, green tea supplementation decreased several cardiovascular risk factors, including body composition, dyslipidemia, inflammatory status, and antioxidant capacity, in rats fed an atherogenic diet. This study supports green tea as an effective dietary component for sustaining cardiovascular health.

Honey promotes lower weight gain, adiposity, and triglycerides than sucrose in rats.

Various dietary carbohydrates have been linked to obesity and altered adipose metabolism; however, the influences of honey vs common sweeteners have not been fully explored. We hypothesized that in comparison with sucrose, a honey-based diet would promote lower weight gain, adiposity, and related biomarkers (leptin, insulin, and adiponectin) as well as a better blood lipid profile. Thirty-six male Sprague-Dawley rats (228.1 ± 12.5 g) were equally divided by weight into 2 groups (n = 18) and provided free access to 1 of 2 diets of equal energy densities differing only in a portion of the carbohydrate. Diets contained 20% carbohydrate (by weight of total diet) from either clover honey or sucrose. After 33 days, epididymal fat pads were excised and weighed, and blood was collected for analyses of serum concentrations of lipids, glucose, and markers of adiposity and inflammation. Body weight gain was 14.7% lower (P ≤ .05) for rats fed honey, corresponding to a 13.3% lower (P ≤ .05) consumption of food/energy, whereas food efficiency ratios were nearly identical. Epididymal fat weight was 20.1% lower (P ≤ .05) for rats fed honey. Serum concentrations of triglycerides and leptin were lower (P ≤ .05) by 29.6% and 21.6%, respectively, and non-high-density lipoprotein cholesterol was higher (P ≤ .05) by 16.8% for honey-fed rats. No significant differences in serum total cholesterol, high-density lipoprotein cholesterol, adiponectin, C-reactive protein, monocyte chemoattractant protein-1, glucose, or insulin were detected. These results suggest that in comparison with sucrose, honey may reduce weight gain and adiposity, presumably due to lower food intake, and promote lower serum triglycerides but higher non-high-density lipoprotein cholesterol concentrations.

Snack selection influences nutrient intake, triglycerides, and bowel habits of adult women: a pilot study.

Because appropriate snacking can promote a healthy body weight and serve as an important contributor to a healthy diet for women, identification of suitable foods for incorporation between meals is essential. We investigated the influence of short-term (2 weeks) incorporation of 100-kcal servings of snacks of dried plums vs low-fat cookies twice daily on total energy and nutrient intake, biochemical parameters, and bowel habits in a randomized crossover design of two 2-week trials separated by a 2-week wash-out period in 26 women aged 25 to 54 years with a body mass index between 24 and 35. Incorporation of dried plums or low-fat cookies into the diet did not alter energy intake or weight; however, compared to cookies, dried plums promoted greater (P< or =0.05) intake of fiber, potassium, riboflavin, niacin, and calcium. Total fat intake tended (P=0.094) to decrease with dried plum consumption, as did cholesterol intake (P=0.098). Plasma triglyceride concentration remained unchanged (P>0.05) by dried plum consumption and was 17.0+/-29.2 mg/dL (0.19+/-0.33 mmol/L) higher (P< or =0.05) after consumption of low-fat cookies vs dried plums at the end of 2 weeks. Dried plums promoted a softer (P< or =0.05) stool consistency vs usual intake and in comparison to intake of low-fat cookies. These results suggest that relative to a commercially processed low-fat cookie snack, dried plums promote more favorable plasma triglyceride responses, improved dietary quality, and slightly improved bowel function.

Type of snack influences satiety responses in adult women.

The effect of different snack foods on satiety and plasma glucose and hormone responses was assessed. Nineteen fasted adult women (mean age: 39.2 + or - 0.7 years, mean BMI: 26.1 + or - 0.8 kg/m(2)) consumed test foods including dried plums, low-fat cookies, white bread and water only on separate days. The test foods (with the exception of water) provided 238 kcal and were similar in total carbohydrate, fat and protein content but differed in fiber and sugar content. Subjects rated their feelings of hunger using satiety index scales prior to snack consumption and again every 15 min for 2h following initiation of intake. Blood samples were collected at baseline and 15, 30, 45, 60, 90, and 120 min following intake. At the end of the 120-min test period, subjects were presented with a meal to be consumed until satisfied. The satiety index AUC was greater for the dried plum trial versus the low-fat cookie trial (p < or = 0.05). There was no difference in post-snack consumption between the dried plums and cookie trials. The dried plums trial elicited lower plasma glucose and insulin AUC than the low-fat cookie trial (p < or = 0.05) and tended to promote a greater plasma ghrelin AOC (p = 0.056). These results demonstrate that consuming dried plums as a snack suppresses hunger relative to a low-fat cookie as evidenced by lower glucose and/or satiety-regulating hormone concentrations.

The effects of high-impact and resistance exercise on urinary calcium excretion.

Although physical activity is known to improve bone mineralization, it is unclear whether this occurs through altered absorption and/or excretion. The purpose of this study was to investigate the effects of a high-impact and resistance-training exercise program versus a period of restricted physical activity on urinary calcium excretion. Ten healthy, moderately active men (27.0 +/- 5.8 yr) participated in a 3-wk randomized crossover study. Participants were assigned to complete either a period of daily participation in exercise including high-impact and resistance-training activities (EX) or a period of restriction in physical activity (NE) for 7 consecutive days. After a 1-wk washout period, participants completed the opposite trial. During both phases, participants consumed four 8-oz servings of low-fat (1%) milk daily and avoided other dietary and supplemental sources of calcium. Urine was collected throughout the final 72 hr of each study phase. Urinary calcium and sodium excretions were 14.7% +/- 17.1% and 15.8% +/- 9.9% lower (p < .05), respectively, during the EX phase than the NE phase. These results occurred despite participants consuming more (p < .05) sodium during the EX phase than the NE phase. These results suggest that healthy, moderately active men excrete significantly less urinary calcium concurrent with lower sodium excretion during a week of performing high-impact and resistance-training exercises versus a week of restricted physical activity. The reduction in urinary loss of calcium might be at least partially responsible for improved bone mineralization that has been observed during periods of greater physical activity.