Acute effects of food on postprandial blood pressure and measures of arterial stiffness in healthy humans

BACKGROUND

Recent research suggests that central pulse pressure may be a better indicator of cardiovascular disease outcomes than brachial pressure. Little information is available regarding the effect of food intake on postprandial central pressure and other measures of arterial stiffness when measured with a noninvasive pulse wave analysis (PWA) technique.

OBJECTIVE

The objective was to investigate the effects of water and food plus water intake on brachial and central blood pressure (BP) and measures of arterial stiffness, including augmentation pressure and augmentation index, by using the PWA technique.

DESIGN

Measurements of BP and PWA were made at fasting and for 2 h after the intake of water or breakfast (1300 kJ) in random order in 35 subjects.

RESULTS

Baseline fasting measures of BP and arterial stiffness were not significantly different before the 2 interventions. Consumption of food plus water, compared with water alone, led to a significantly lower (all P < 0.01) brachial diastolic pressure (difference: -3.8 mm Hg), central BP (difference: systolic, -6.1 mm Hg; diastolic, -3.8 mm Hg), central pulse pressure (difference: -2.4 mm Hg), mean arterial pressure (difference: -4.6 mm Hg), augmentation pressure (difference: -2.9 mm Hg), and augmentation index (difference: -5.3 mm Hg).

CONCLUSIONS

Markers of central hemodynamics are sensitive to feeding state and therefore should be measured at fasting to avoid variability due to recent (within 2-3 h) food intake. This is especially important when measurements are repeated over time to assess the effect of medication or lifestyle changes on cardiovascular disease risk factors.

Effects of a Controlled Diet Supplemented with Chickpeas on Serum Lipids, Glucose Tolerance, Satiety and Bowel Function

OBJECTIVE

To compare the effect of a diet supplemented with chickpeas to a wheat-based diet of similar fibre content on serum lipids, glucose tolerance, satiety and bowel function. A third, lower-fibre wheat diet provided further information on dietary fibre quantity and bowel function and satiety.

METHOD

Twenty-seven free-living adults followed two randomized, crossover dietary interventions each of five weeks duration. The chickpea diet included canned drained chickpeas, bread and shortbread biscuits containing 30% chickpea flour. The wheat diet included high-fibre wheat breakfast cereals and wholemeal bread. The diets were isoenergetic to the participants' usual diet, matched for macronutrient content and controlled for dietary fibre. Following on from the second randomised intervention, a sub-group of 18 participants underwent a third, isoenergetic lower-fibre wheat diet that included low-fibre breakfast cereals and bread.

RESULTS

Repeated measures ANOVA revealed reductions in serum TC of 0.25 mmol/L (p < 0.01) and LDL-C of 0.20 mmol/L (p = 0.02) following the chickpea diet compared to the wheat. An unintended significant increase in PUFA and corresponding decrease in MUFA consumption occurred during the chickpea diet and statistical adjustment for this reduced but did not eliminate the effect on serum lipids. There was no significant difference in glucose tolerance. Perceived general bowel health improved significantly during the chickpea diet although there was considerable individual variation. Some participants reported greater satiety during the chickpea diet.

CONCLUSIONS

The small but significant decrease in serum TC and LDL-C during the chickpea diet compared to the equivalent fibre wheat diet was partly due to unintentional changes in macronutrient intake occurring because of chickpea ingestion. If dietary energy and macronutrients were not controlled, chickpea consumption might result in greater benefits via influence on these factors.

Effects of daily ingestion of chilli on serum lipoprotein oxidation in adult men and women

Laboratory studies have shown that the resistance of isolated LDL-cholesterol or linoleic acid to oxidation is increased in incubations with chilli extracts or capsaicin – the active ingredient of chilli. It is unknown if these in vitro antioxidative effects also occur in the serum of individuals eating chilli regularly. The present study investigated the effects of regular consumption of chilli on in vitro serum lipoprotein oxidation and total antioxidant status (TAS) in healthy adult men and women. In a randomised cross-over study, twenty-seven participants (thirteen men and fourteen women) ate ‘freshly chopped chilli’ blend (30g/d; 55% cayenne chilli) and no chilli (bland) diets, for 4 weeks each. Use of other spices, such as cinnamon, ginger, garlic and mustard, was restricted to minimum amounts. At the end of each dietary period serum samples were analysed for lipids, lipoproteins, TAS and Cu-induced lipoprotein oxidation. Lag time (before initiation of oxidation) and rate of oxidation (slope of propagation phase) were calculated. There was no difference in the serum lipid, lipoproteins and TAS at the end of the two dietary periods. In the whole group, the rate of oxidation was significantly lower (mean difference −0·23 absorbance ×10−3/min; P=0·04) after the chilli diet, compared with the bland diet. In women, lag time was higher (mean difference 9·61min; P<0·001) after the chilli diet, compared with the bland diet. In conclusion, regular consumption of chilli for 4 weeks increases the resistance of serum lipoproteins to oxidation.

Dietary supplementation with chickpeas for at least 5 weeks results in small but significant reductions in serum total and low-density lipoprotein cholesterols in adult women and men

AIM

To compare the effects of a chickpea-supplemented diet and those of a wheat-supplemented diet on human serum lipids and lipoproteins.

METHODS

Forty-seven free-living adults participated in a randomized crossover weight maintenance dietary intervention involving two dietary periods, chickpea-supplemented and wheat-supplemented diets, each of at least 5 weeks duration.

RESULTS

The serum total cholesterol and low-density lipoprotein cholesterol levels were significantly lower (both p < 0.01) by 3.9 and 4.6%, respectively, after the chickpea-supplemented diet as compared with the wheat-supplemented diet. Protein (0.9% of energy, p = 0.01) and monounsaturated fat (3.3% of total fat, p < 0.001) intakes were slightly but significantly lower and the carbohydrate intake significantly higher (1.7% of energy, p < 0.001) on the chickpea-supplemented diet as compared with the wheat-supplemented diet. Multivariate analyses suggested that the differences in serum lipids were mainly due to small differences in polyunsaturated fatty acid and dietary fibre contents between the two intervention diets.

CONCLUSIONS

Inclusion of chickpeas in an intervention diet results in lower serum total and low-density lipoprotein cholesterol levels as compared with a wheat-supplemented diet.

The effect of 4-week chilli supplementation on metabolic and arterial function in humans

OBJECTIVE

To investigate the effects of regular chilli ingestion on some indicators of metabolic and vascular function.

DESIGN

A randomized cross-over dietary intervention study.

SETTING

Launceston, Australia.

SUBJECTS

Healthy free-living individuals.

INTERVENTION

Thirty-six participants (22 women and 14 men), aged 46+/-12 (mean+/-s.d.) years; BMI 26.4+/-4.8 kg/m(2), consumed 30 g/day of a chilli blend (55% cayenne chilli) with their normal diet (chilli diet), and a bland diet (chilli-free) for 4 weeks each. Metabolic and vascular parameters, including plasma glucose, serum lipids and lipoproteins, insulin, basal metabolic rate, blood pressure, heart rate, augmentation index (AIx; an indicator of arterial stiffness), and subendocardial-viability ratio (SEVR; a measure of myocardial perfusion), were measured at the end of each diet. In a sub-study, during week 3 of each dietary period, the vascular responses of 15 subjects to glyceryl-trinitrate (GTN) and salbutamol were also studied.

RESULTS

For the whole group, there were no significant differences between any of the measured parameters when compared at the end of the two dietary periods. When analysed separately, men had a lower resting heart rate (P=0.02) and higher SEVR (P=0.05) at the end of the chilli diet than the bland diet. In the sub-study, baseline AIx on the chilli diet was lower (P<0.001) than on the bland diet, but there was no difference in the effects of GTN and salbutamol between the two diets.

CONCLUSION

Four weeks of regular chilli consumption has no obvious beneficial or harmful effects on metabolic parameters but may reduce resting heart rate and increase effective myocardial perfusion pressure time in men.

Effects of capsaicin, dihydrocapsaicin, and curcumin on copper-induced oxidation of human serum lipids

The oxidation of low-density lipoprotein (LDL) is believed to be the initiating factor for the development and progression of atherosclerosis. The active ingredients of spices such as chili and turmeric (capsaicin and curcumin, respectively) have been shown to reduce the susceptibility of LDL to oxidation. One of the techniques used to study the oxidation of LDL is to isolate LDL and subject it to metal-induced (copper or iron) oxidation. However, whole serum may represent a closer situation to in vivo conditions than using isolated LDL. We investigated the effects of different concentrations (0.1-3 microM) of capsaicin, dihydrocapsaicin, and curcumin on copper-induced oxidation of serum lipoproteins. The lag time (before initiation of oxidation) and rate of oxidation (slope of propagation phase) were calculated. The lag time increased, and the rate of oxidation decreased with increasing concentrations of the tested antioxidants (p < 0.05). A 50% increase in lag time (from control) was observed at concentrations between 0.5 and 0.7 microM for capsaicin, dihydrocapsaicin, and curcumin. This study shows that oxidation of serum lipids is reduced by capsaicinoids and curcumin in a concentration-dependent manner.

Effects of olive oil and tomato lycopene combination on serum lycopene, lipid profile, and lipid oxidation

OBJECTIVE

We compared the effect of two diets (a diet high in olive oil and a diet high in carbohydrate and low in olive oil) with high lycopene content and other controlled carotenoids on serum lycopene, lipids, and in vitro oxidation.

METHODS

This was a randomized crossover dietary intervention study carried out in Launceston, Tasmania, Australia in healthy free-living individuals. Twenty-one healthy subjects who were 22 to 70 y old were recruited by advertisements in newspapers and a university newsletter. A randomized dietary intervention was done with two diets of 10 d each. One diet was high in olive oil and the other was high in carbohydrate and low in olive oil; the two diets contained the same basic foods and a controlled carotenoid content high in lycopene.

RESULTS

Significant increases (P<0.001) in serum lycopene concentration on both diets were to similar final concentrations. Higher serum high-density lipoprotein cholesterol (P<0.01), lower ratio of total cholesterol to high-density lipoprotein (P<0.01), and lower triacylglycerols (P<0.05) occurred after the olive oil diet compared with the high-carbohydrate, low-fat diet. There was no difference in total antioxidant status and susceptibility of serum lipids to oxidation.

CONCLUSIONS

Serum lycopene level changes with dietary lycopene intake irrespective of the amount of fat intake. However, a diet high in olive oil and rich in lycopene may decrease the risk of coronary heart disease by improving the serum lipid profile compared with a high-carbohydrate, low-fat, lycopene-rich diet.

Effects of two lipid-lowering, carotenoid-controlled diets on the oxidative modification of low-density lipoproteins in free-living humans

This study compares the effects of two lipid-lowering diets [a diet enriched in MUFAs (monounsaturated fatty acids) and a HCLF (high-carbohydrate/low-fat) diet] with a controlled carotenoid content on risk factors for coronary heart disease, including in vitro copper-induced LDL (low-density lipoprotein) oxidation and serum lipid levels. A randomized crossover dietary intervention study, with two diets each consumed for 14-16 days, was conducted in 18 women and 13 men aged 20-70 years, recruited via personal contacts and advertisements in newspapers. Both diets (MUFA-enriched diet and HCLF diet) contained the same basic foods and had a controlled carotenoid content, high in lycopene. The in vitro copper-induced oxidation of isolated LDL showed a longer lag phase (mean difference 7.4 min in women and 7.34 min in men) after the MUFA-enriched diet compared with the HCLF diet. Serum total cholesterol, LDL cholesterol and carotenoid levels were similar after the two diets. Serum triacylglycerol levels were significantly lower and those of HDL (high-density lipoprotein) cholesterol were significantly higher at the end of the MUFA-enriched diet compared with the HCLF diet. It is concluded that the significantly longer lag phase for oxidation of LDL, the higher HDL cholesterol level and the lower triacylglycerol level in subjects following a carotenoid-controlled, MUFA-enriched diet may decrease the risk of coronary heart disease.

Effects of a high monounsaturated fat, tomato-rich diet on serum levels of lycopene

OBJECTIVE

To compare the effect of a modified fat, monounsaturated-fat-enriched diet and a high-carbohydrate low-fat diet with high lycopene content on the serum concentration of lycopene and other carotenoids.

DESIGN

A randomised crossover dietary intervention study.

SETTING

Melbourne, Australia--Healthy free-living men.

SUBJECTS

A total of 13 healthy males between the age of 20 and 70 y, recruited via advertisements in newspapers and university newsletter.

INTERVENTION

A randomised dietary intervention with two diets of 14 days each. The two diets were--(1) high-fat monounsaturated-fat-enriched (MUFA) and (2) high-carbohydrate low-fat (HCLF). Both the diets contained the same basic foods and a controlled carotenoid content high in lycopene.

RESULTS

A significant increase in serum total lycopene occurred, by 126% on the MUFA diet (P <0.001) and 108% on the HCLF diet (P=0.001). A reduction in serum cryptoxanthin (27% on MUFA diet and 25% on HCLF) and alpha-carotene (43% on the MUFA diet and 25% on the HCLF diet) was observed. No change was observed for the other carotenoids. Comparing the end of the two diets, no statistically significant difference was observed for lycopene or the other carotenoids.

CONCLUSION

In all, 15% of energy from fat or 38% of energy from fat (predominantly monounsaturated fat) in the diet does not have a significant differential effect on serum lycopene.

SPONSORSHIP

The study was partially funded by the Grains Research Development Corporation, Canberra and Meadow Lea Foods Ltd, Mascot, Australia. HJ Heinz, Melbourne, Australia provided the tomato products and some funds for their carotenoid analysis.