Influence of aging and menopause on postprandial lipoprotein responses in healthy adult women

Effect of fat ingestion on postprandial oxidative status in healthy young women: a pilot study

Reactive oxygen species (ROS) and highly reactive oxygen species (hROS) secreted by leukocytes are crucial to innate immunity; however, they pose a risk of oxidative stress. To monitor their balance in daily health check-ups, optical technologies for the simultaneous measurement of ROS (superoxide radicals) and hROS (hypochlorite ions) that utilize only a few microliters of whole blood have been developed. The aim of this study was to clarify whether this system could assess the effects of fat ingestion on postprandial oxidative status. Eight healthy young Japanese women ingested a beverage containing oral fat tolerance test cream. Blood samples were collected before and 0.5, 1, 2, 4, and 6 h after fat ingestion. Blood ROS and hROS levels, oxidative stress markers, and biochemical markers were monitored. Consistent with previous studies, triglyceride levels significantly increased at 4 h (p<0.01) and returned to near-baseline levels 6 h after ingestion. ROS levels peaked significantly at 2 h (p<0.05), and hROS levels peaked significantly at 1 (p<0.05) and 2 h (p<0.01) after ingestion. This study offers an insight into the acute effects of fat ingestion on leukocyte activity and provides a methodology for monitoring postprandial oxidative status.

Effect of Prior Exercise on Postprandial Lipemia: An Updated Meta-Analysis and Systematic Review

The purpose of this systematic review was to synthesize the results from current literature examining the effects of prior exercise on the postprandial triglyceride (TG) response to evaluate current literature and provide future direction. A quantitative review was performed using meta-analytic methods to quantify individual effect sizes. A moderator analysis was performed to investigate potential variables that could influence the effect of prior exercise on postprandial TG response. Two hundred and seventy-nine effects were retrieved from 165 studies for the total TG response and 142 effects from 87 studies for the incremental area under the curve TG response. There was a moderate effect of exercise on the total TG response (Cohen's d = -0.47; p < .0001). Moderator analysis revealed exercise energy expenditure significantly moderated the effect of prior exercise on the total TG response (p < .0001). Exercise modality (e.g., cardiovascular, resistance, combination of both cardiovascular and resistance, or standing), cardiovascular exercise type (e.g., continuous, interval, concurrent, or combined), and timing of exercise prior to meal administration significantly affected the total TG response (p < .001). Additionally, exercise had a moderate effect on the incremental area under the curve TG response (Cohen's d = -0.40; p < .0001). The current analysis reveals a more homogeneous data set than previously reported. The attenuation of postprandial TG appears largely dependent on exercise energy expenditure (∼2 MJ) and the timing of exercise. The effect of prior exercise on the postprandial TG response appears to be transient; therefore, exercise should be frequent to elicit an adaptation.

Acute exercise effects on postprandial fat oxidation: meta-analysis and systematic review

The purpose of this systematic review was to synthesize and evaluate current literature examining the effects of exercise on postprandial fat oxidation, as well as to provide future direction. A quantitative review was performed using meta-analytic methods. A moderator analysis was performed to investigate potential variables that could influence the effect of exercise on postprandial fat oxidation. Fifty-six effects from 26 studies were retrieved. There was a moderate effect of exercise on postprandial fat oxidation (Cohen's d = 0.58 (95% CI, 0.39 to 0.78)). Moderator analysis revealed that sex, age, weight status, training status, exercise type, exercise intensity, timing of exercise, and composition of the meal challenge significantly affected the impact of prior exercise on postprandial fat oxidation. The moderator analysis also indicated that most previous studies have investigated the impact of prior moderate-intensity endurance exercise on postprandial fat oxidation in young, healthy, lean men. Suggested priorities for future research in this area include (i) an examination of sex differences in and/or female-specific aspects of postprandial metabolism; (ii) a comprehensive evaluation of exercise modalities, intensities, and durations; and (iii) a wider variety of test meal compositions, especially those with higher fat content. Novelty A systematic review of the impact of exercise on postprandial fat oxidation was performed using meta-analytic methods. Analysis revealed a moderate effect of exercise on postprandial fat oxidation. The presented data support a need for future studies to investigate sex differences and to include comprehensive evaluations of exercise modalities, intensities, and duration.

Postprandial Metabolic Responses Differ by Age Group and Physical Activity Level

OBJECTIVES

To compare the postprandial metabolic responses to a high-fat meal in healthy adults who differ by age and physical activity level.

DESIGN

Cross-sectional, quasi-experimental design.

SETTING

Physical Activity and Nutrition Clinical Research Consortium (PAN-CRC) at Kansas State University (Manhattan, KS, USA).

PARTICIPANTS

Twenty-two healthy adults: 8 younger active (YA) adults (4M/4W; 25 ± 5 yr), 8 older active (OA) adults (4M/4W; 67 ± 5 yr), and 6 older inactive (OI) adults (3M/3W; 68 ± 7 yr).

INTERVENTION

Following an overnight (10-hour) fast and having abstained from exercise for 2 days, participants consumed a high-fat meal (63% fat, 34% CHO; 12 kcal/kg body mass; 927 ± 154 kcal). To assess the metabolic response, blood draws were performed at baseline and each hour following the meal for 6 hours.

MEASUREMENTS

Fasting and postprandial triglycerides (TG), glucose, Total-C, and HDL-C were measured. Metabolic load index (MLI) and LDL-C were calculated.

RESULTS

There were significant group x time interactions for TG (p < 0.0001) and MLI (p = 0.004). The TG total area-under-the-curve (tAUC) response was significantly lower in YA (407.9 ± 115.1 mg/dL 6 hr) compared to OA (625.6 ± 169.0 mg/dL 6 hr; p = 0.02) and OI (961.2 ± 363.6 mg/dL 6 hr; p = 0.0002), while the OA group TG tAUC was lower than the OI group (p = 0.02). The TG peak was significantly lower in YA (90.5 ± 27.0 mg/dL) than OA (144.0 ± 42.2 mg/dL; p = 0.03) and OI (228.2 ± 96.1 mg/dL; p = 0.0003), and was lower in the OA group compared to the OI group (p = 0.03). Glucose was significantly lower 1 hour after the meal in YA (89.4 ± 10.1 mg/dL; p = 0.01) and OA (87.3 ± 22.3 mg/dL; p = 0.005) versus OI (110.7 ± 26.9 mg/dL). MLI tAUC was significantly lower in YA (936.8 ± 137.7 mg/dL 6 hr; p = 0.0007) and OA (1133.0 ± 207.4 mg/dL; p = 0.01) versus OI (1553.8 ± 394.3 mg/dL), with no difference (p = 0.14) between YA and OA groups. Total-C and LDL-C were generally lower in younger compared to older participants at baseline and throughout the postprandial period, while no group or time effects were evident in HDL-C.

CONCLUSION

Both physical activity status and aging appear to affect the postprandial metabolic, namely TG, response to a high-fat meal. These findings point to an inherently diminished metabolic capacity with aging, but suggest that physical activity may help minimize this decrement.

Postprandial lipemia: factoring in lipemic response for ranking foods for their healthiness

One of the limitations for ranking foods and meals for healthiness on the basis of the glycaemic index (GI) is that the GI is subject to manipulation by addition of fat. Postprandial lipemia, defined as a rise in circulating triglyceride containing lipoproteins following consumption of a meal, has been recognised as a risk factor for the development of cardiovascular disease and other chronic diseases. Many non-modifiable factors (pathological conditions, genetic background, age, sex and menopausal status) and life-style factors (physical activity, smoking, alcohol and medication use, dietary choices) may modulate postprandial lipemia. The structure and the composition of a food or a meal consumed also plays an important role in the rate of postprandial appearance and clearance of triglycerides in the blood. However, a major difficulty in grading foods, meals and diets according to their potential to elevate postprandial triglyceride levels has been the lack of a standardised marker that takes into consideration both the general characteristics of the food and the food’s fat composition and quantity. The release rate of lipids from the food matrix during digestion also has an important role in determining the postprandial lipemic effects of a food product. This article reviews the factors that have been shown to influence postprandial lipemia with a view to develop a novel index for ranking foods according to their healthiness. This index should take into consideration not only the glycaemic but also lipemic responses.

The Ingestion of a Fructose-Containing Beverage Combined with Fat Cream Exacerbates Postprandial Lipidemia in Young Healthy Women

AIM

To investigate the acute effects of the ingestion of a fructose-containing beverage combinedwith fat on postprandial lipoprotein metabolism.

METHODS

Twelve young healthy Japanese women with apolipoprotein E phenotype 3/3 were enrolled in this study. At each of four sessions, the subjects ingested one of four sugar beverages containing fructose and/or glucose (total: 0.5g/kg body weight) combined with OFTT cream (1g/kg, 0.35g/kg as fat) in a randomized crossover design. The four sugar beverages were as follows: 100% (w/w) fructose (F100), 90% fructose+10% glucose (F90G10), 55% fructose+45% glucose (F55G45) and 100% glucose (G100). Venous blood samples were obtained at baseline and 0.5, one, two, four and six hours after ingestion.

RESULTS

The serum concentrations of TG in the F100, F90G10 and F55G45 trials were significantlyhigher than each fasting value at two and four hours, and returned to baseline at six hours, except inthe F100 trial. The concentrations at four hours and the incremental areas under the curve for thehepatic triglyceride-rich lipoprotein-triglyceride (VLDL-TG(TM)) levels in the F100 and F90G10 trialswere significantly higher and larger, respectively, than those observed in the G100 trial. Meanwhile,the concentrations of RLP-TG and apolipoprotein B-48 peaked at two hours in the G100 trial, versusfour hours in the other trials, and did not return to baseline at six hours, except in the G100 trial.At four hours, the ⊿apoB48 tended to be higher in the F100 trial than in the G100 trial.

CONCLUSIONS

The ingestion of a high-fructose-containing beverage with fat cream delays the clearance of chylomicron and its remnant derived from the intestine and enhances the secretion of triglyceride-rich lipoprotein particles from the liver, thereby inducing postprandial lipidemia, even in young healthy women.

Clinical considerations and mechanistic determinants of postprandial lipemia in older adults

The typical diet of individuals in Western societies results in metabolic responses associated with fed-state fat metabolism for most of the daily life of the individual. This fat metabolism is characterized specifically by an increase in the concentration of plasma lipids, primarily triglycerides. Increased postprandial lipemia, which is typically observed in older individuals (i.e., >65 y old), has now emerged as an important correlate of cardiovascular disease risk. An understanding of the mechanisms contributing to the increased postprandial lipemia in older individuals becomes, therefore, of particular clinical importance in any effort to explain and address the well-documented increase in cardiovascular disease risk as individuals age. Current evidence points to an increase in the accumulation of ingested lipid in lipoprotein particles of hepatic origin, together with an overall accumulation of lipid in these lipoproteins during the postprandial period, as primary contributors to the postprandial lipemia in older persons. When this evidence is considered together with the evidence suggesting large atherogenic potential of lipoproteins of hepatic origin, this can, at least in part, explain the increased risk of cardiovascular disease in older individuals. Understanding changes in the metabolism of ingested fat in the immediate postprandial period with advancing age, and how lifestyle interventions such as diet and physical exercise can ameliorate the increase in postprandial lipemia in older individuals, is important in order to address the increased cardiovascular disease risk in this particularly affected and growing segment of the population.

Independent association between age at natural menopause and hypercholesterolemia, hypertension, and diabetes mellitus: Japan nurses' health study

AIM

Menopause is considered a cardiovascular risk factor (CRF), but age at menopause (AAM) varies considerably and could affect the risk among post-menopausal women. The aim of the study was to clarify whether AAM is associated with hypertension, diabetes mellitus (DM) and hypercholesterolemia, independent of chronological age, lifestyle and hormone replacement therapy (HRT), in a sizeable number of Japanese women.

METHODS

A retrospective study was conducted using the baseline survey of the ongoing large prospective Japan Nurses' Health Study. The prevalence of hypertension, DM, and hypercholesterolemia of pre-menopausal and three post-menopausal AAM groups (early: <45 years, intermediate: 45-53 years, late: >53 years) was compared among 22,426 women aged 40-59 years. Daily lifestyle such as smoking, alcohol consumption, and physical activity were included.

RESULTS

The estimated risk (odds ratio: OR) was significantly higher in post-menopausal women and linearly elevated according to the AAM groups, and the late AAM group was more likely to have hypertension, DM, or hypercholesterolemia; however, after adjustment for age, BMI (kg/m(2)), HRT and lifestyle, menopause and AAM showed a significant association with only hypercholesterolemia and the early AAM group had the highest OR (2.72 (1.93-3.82)). Menopause and AAM did not show any independent association with the risk of hypertension and DM in the fully adjusted model.

CONCLUSIONS

Among the post-menopausal women, early menopause increased the risk for hypercholesterolemia independently. AAM can be a useful screening tool to identify women at high risk for adverse post-menopausal lipid profiles in the Japanese.

Postprandial lipemia in pre- and postmenopausal women

Background and Objective:

The increased risk for coronary artery disease observed in postmenopausal (PoW) women is partly explained by a more atherogenic lipoprotein profile. Moreover, natural menopause has been associated with an altered postprandial lipid profile. This study was designed to test the hypothesis that young premenopausal (PrW) and PoW may be independently associated with postprandial lipemia and indirectly associated with atherosclerosis.

Patients and Methods:

A total of 46 healthy PrW and 44 healthy PoW participated in a 5-h intervention study. Blood samples were taken at the baseline and at 1, 2, 3, and 4 h after eating. Total cholesterol, LDL-cholesterol, HDL-cholesterol, fasting, and postprandial triglycerides (PPTG) were determined sequentially in blood samples.

Results:

PPTG presented significant higher values in PoW compared to PrW (P < 0.05), but other lipids did not significantly differ between groups. PPTG concentrations in PoW were significantly higher than in PrW (P < 0.05). There was a significant time influence (P < 0.05) in TG in PrW and PoW, while time to peak and peak concentration were significantly higher in PoW than PrW. Other lipids were also decreased more in PrW than PoW, but not significantly so. Cholesterol concentrations showed a significant reduction after 2 h, to reach values similar to the baseline after 4 h in PrW but not in PoW. HDL-cholesterol concentration was decreased more in PoW compared to PrW but it was not significant.

Conclusions:

Lipid postprandial response indicates a higher cardiovascular risk pattern in PoW compared to PrW.

Pitavastatin prevents postprandial endothelial dysfunction via reduction of the serum triglyceride level in obese male subjects

Obesity is a well-established risk factor for the development and progression of coronary heart disease. Moreover, endothelial dysfunction is an early event in atherosclerosis and is known to be associated with postprandial hypertriglyceridemia. The purpose of this study was to determine whether a statin might have an effect on postprandial hypertriglyceridemia, and thereby on endothelial function in obese subjects. Twenty-four obese male subjects were recruited for this study. They were randomly assigned to receive pitavastatin (2 mg/day) or placebo for 2 weeks. The oral fat loading test using OFTT cream was performed pre- and post-treatment, in which the lipid profile and flow-mediated dilation (FMD) were assessed before and 4 h after an oral fat load. In the oral fat loading test conducted pretreatment, the oral fat load induced a marked increase of the serum triglyceride (TG) level and decrease in FMD in the pitavastatin and placebo group. In the test conducted post-treatment, the increase in postprandial TG was attenuated (+183 vs. +81 mg/dL, P < 0.001) and decrease in postprandial FMD was completely abolished (-1.1 vs. +0.1%, P < 0.01) by pitavastatin treatment. Moreover, there was a good correlation between the change in postprandial TG and the change in postprandial FMD after the 2 weeks of treatment (r = -0.737, P < 0.001). Pitavastatin might prevent endothelial dysfunction caused by postprandial hypertriglyceridemia within 2 weeks of therapy in obese subjects.

Delayed postprandial metabolism of triglyceride-rich lipoproteins in obese young men compared to lean young men

BACKGROUND

Obesity, especially visceral obesity, has been known to affect lipoprotein metabolism, but it is not clear whether obesity in young, apparently healthy men is associated with postprandial triglyceride-rich lipoprotein (TRL) metabolism.

METHODS

Ten young normolipidemic, normoglycemic obese men (20.6 ± 0.5 y, BMI 27.5 ± 1.0 kg/m(2)) and 11 lean healthy men (22.1 ± 0.4 y, 21.2 ± 0.4 kg/m(2)) ingested OFTT cream (1g/kg body weight). Fasting and postprandial blood samples were obtained for up to 6h, and serum lipids and lipoproteins were analyzed.

RESULTS

The obese men with a fasting triglyceride (TG) in the normal range and not different from the fasting value of lean controls had a prolonged postprandial response, indicated by a significantly greater incremental areas under the curve in serum TG, TRL-TG, and remnant-like particle-cholesterol (RLP-C) compared with controls. Plasma glucose levels did not change during the test. Differences in serum insulin levels and homeostasis model assessment-insulin resistance (HOMA-IR) were not statistically significant between the two groups; however, trends toward higher levels were shown in obese young men.

CONCLUSIONS

The obese young men showed significantly delayed TRL metabolism compared to the lean young men after fat loading, even though the obese men were normolipidemic. These results suggest the possibility that early insulin resistance in the obese young men may have caused the decrease of lipoprotein lipase activity and induced delayed TRL metabolism. A fat loading test without carbohydrate may provide a useful tool for the detection of delayed postprandial TRL metabolism and early insulin resistance.

Difference between fasting and nonfasting triglyceridemia; the influence of waist circumference

AIM

Postprandial hypertriglyceridemia is recognized as an independent risk factor for cardiovascular disease. The aim of this study was to identify differences between fasting and postprandial TG levels, focusing on the influence of waist circumference.

METHODS

Subjects included 1,505 men and 798 women aged 3865 years who were not taking medications for diabetes or dyslipidemia. Fasting TG levels were measured after an overnight fast, and postprandial TG levels were measured 2 hours after a standardized rice-based lunch (total 740 kcal, 20 g fat, 30 g protein, and 110 g carbohydrates) in the afternoon on the same day.

RESULTS

Fasting and postprandial TG levels were highly correlated in both men (r=0.86, p<0.001) and women (r=0.84, p<0.001). Waist circumference was positively correlated with fasting TG (r=0.38 in men and r=0.36 in women) and postprandial TG (r=0.42 in men and r=0.45 in women), respectively. On multiple regression analyses, the association of waist circumference with postprandial TG was still significant (standardized beta=0.10 in men and standardized beta=0.15 in women, p<0.001) after the inclusion of HbA1c, age, high-density-lipoprotein (HDL)-cholesterol, alcohol consumption, and fasting TG in the regression model.

CONCLUSION

Postprandial TG has a better relation with waist circumference than fasting TG.

Impact of age and menopausal status on the postprandial triacylglycerol response in healthy women

OBJECTIVE

To examine the impact of age and the natural menopause on the postprandial triacylglycerol (TAG) response in healthy women.

METHODS AND RESULTS

Thirty-seven premenopausal and sixty-one postmenopausal women underwent a sequential meal postprandial investigation, in which blood samples were taken at regular intervals after a test breakfast and lunch given at 0 and 330 min respectively. Lipids and glucose were measured in the fasting sample, with TAG analysed in the postprandial samples. Postmenopausal women were shown to have higher fasting total cholesterol, low density lipoprotein cholesterol (LDL-C) and glucose (P<0.02). Marked differences in the postprandial TAG response were evident between the groups, with a greater incremental area under the curve (IAUC) and maximum TAG concentration in the postmenopausal women (P<0.04). Multivariate regression analysis revealed both age and fasting TAG to be independently associated with the summary measures of the postprandial TAG response in the premenopausal women only. Interestingly, sub-division of the women into both younger and older pre- and postmenopausal subgroups, showed the most marked difference in TAG-IAUC to be between the younger and the older premenopausal women, whereas differences in fasting LDL-C were most evident between the older premenopausal and the younger postmenopausal women.

CONCLUSIONS

Our results suggest a divergence in the relationship of age and menopausal status with fasting LDL-C and postprandial TAG which may reflect differences in the metabolic effects of age and the menopause on these lipid risk markers or a greater impact of early oestrogen decline on pathways of TAG rather than LDL metabolism.

Consuming fructose-sweetened, not glucose-sweetened, beverages increases visceral adiposity and lipids and decreases insulin sensitivity in overweight/obese humans

Studies in animals have documented that, compared with glucose, dietary fructose induces dyslipidemia and insulin resistance. To assess the relative effects of these dietary sugars during sustained consumption in humans, overweight and obese subjects consumed glucose- or fructose-sweetened beverages providing 25% of energy requirements for 10 weeks. Although both groups exhibited similar weight gain during the intervention, visceral adipose volume was significantly increased only in subjects consuming fructose. Fasting plasma triglyceride concentrations increased by approximately 10% during 10 weeks of glucose consumption but not after fructose consumption. In contrast, hepatic de novo lipogenesis (DNL) and the 23-hour postprandial triglyceride AUC were increased specifically during fructose consumption. Similarly, markers of altered lipid metabolism and lipoprotein remodeling, including fasting apoB, LDL, small dense LDL, oxidized LDL, and postprandial concentrations of remnant-like particle-triglyceride and -cholesterol significantly increased during fructose but not glucose consumption. In addition, fasting plasma glucose and insulin levels increased and insulin sensitivity decreased in subjects consuming fructose but not in those consuming glucose. These data suggest that dietary fructose specifically increases DNL, promotes dyslipidemia, decreases insulin sensitivity, and increases visceral adiposity in overweight/obese adults.