BackgroundThe consumption of low glycemic index (LGI) foods before exercise results in slower and more stable glycemic increases. Besides maintaining an adequate supply of energy during exercise, this response may favor an increase in fat oxidation in the postprandial period before the exercise compared to high glycemic index (HGI) foods. The majority of the studies that evaluated the effect of foods differing in glycemic index on substrate oxidation during the postprandial period before the exercise are acute studies in which a single meal is consumed right before the exercise. The purpose of this study was to investigate the effect of consuming two daily HGI or LGI meals for five consecutive days on substrate oxidation before the exercise and in the concentrations of glucose, insulin and free fatty acids before and during a high intensity exercise.MethodsFifteen male cyclists, aged 24.4 ± 3.8 years, with body mass index of 21.9 ± 1.4 kg.m-2 and a VO2 max of 70.0 ± 5.3 mL.kg-1.min-1, participated in this crossover study. All test meals were consumed in the laboratory. On days 1 and 5, substrate oxidation (30 minutes before and 90 minutes after breakfast (HGI or LGI)) and diet-induced thermogenesis (90 minutes postprandial) were assessed before the exercise. The levels of glucose, insulin, and free fatty acids were determined during 2 h after breakfast on these same days. Ninety minutes after breakfast, subjects completed a 30 min cycloergometric exercise at 85 to 95% of their maximum heart rate, during which lactate concentrations were assessed.ResultsThe consumption of HGI meals resulted in higher areas under the glycemic and insulinemic curves in the postprandial period. However, glycemia did not differ by study treatment during exercise. There were no differences in free fatty acids in the postprandial period or in lactate levels during exercise. LGI meals resulted in lower fat oxidation and higher carbohydrate oxidation than the HGI meal in the postprandial period.ConclusionsThe results do not support a differential glycemia according to glycemic index during exercise. The ingestion of LGI foods did not lead to higher fat oxidation relative to the ingestion of HGI foods.Trial registrationACTRN: ACTRN12609000522213

Red meat consumption was cross-sectionally associated with the occurrence of central obesity, hypertriglyceridaemia, and metabolic syndrome as well as with higher homeostatic model assessment for insulin resistance, oxidized low-density lipoprotein concentrations and triglycerides:high-density lipoprotein cholesterol ratio. The content of saturated fatty acid from red meat consumption may be a factor that contributed to this relationship, while white meat consumption was not associated with metabolic syndrome and the assessed biomarkers.

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The present cross-sectional study assessed the potential relationships of carotenoid intake with lipid and oxidative stress markers in middle-aged men. A total of 296 apparently healthy middle-aged men (mean age 50·5 (SD 5·0) years, BMI 25·8 (SD 3·5) kg/m 2 ) were recruited to participate in the study. Dietary intake, anthropometry, blood pressure, lifestyle features, blood and urine biomarkers were assessed using validated procedures. The lipid markers included NEFA, Castelli index, and TAG:HDL ratio; oxidative stress markers included urinary 8-hydroxy-2 0 -deoxyguanosine (8-OHdG), 8-iso-PGF2a and plasma oxidised-LDL (ox-LDL). We observed a significant inverse association (P, 0·05) between NEFA concentrations and consumption of lutein plus zeaxanthin, b-carotene, a-carotene and total carotenoid, while Castelli index was negatively associated with daily intake of lycopene, b-carotene and total carotenoids. Regarding oxidative stress biomarkers, urinary 8-OHdG and ox-LDL concentrations were also inversely associated (P, 0·05) with consumption of lycopene, lutein plus zeaxanthin, b-carotene, a-carotene and total carotenoids, regardless of confounding variables. Moreover, there was a negative association of urinary 8-iso-PGF2a concentration with dietary lutein plus zeaxanthin (b 20·135, 95 % CI 20·268, 20·001), b-carotene (b 20·156, 95 % CI 20·277, 2 0·034) and with the sum of all carotenoids (b 2 0·189, 95 % CI 2 0·333, 20·046). In conclusion, total daily carotenoid intake based on five investigated carotenoid types (b-cryptoxanthin, lycopene, lutein plus zeaxanthin, b-carotene and a-carotene) was inversely associated with relevant lipid and oxidative stress markers in middle-aged men, with emphasis on b-carotene that was negatively associated with five of the six lipid and oxidative stress markers evaluated in the present study.

The prevalence of vitamin D inadequacy varied significantly according to the adopted criteria. There was a seasonal variation of 25(OH)D during pregnancy. The women with insufficient vitamin D status present greater longitudinal increases in the concentrations of 1,25(OH)D in comparison to women with sufficiency.