Effects of low-fat dairy intake on blood pressure, endothelial function, and lipoprotein lipids in subjects with prehypertension or stage 1 hypertension

The relationship between the intake of fruits, vegetables, and dairy products with hypertension: findings from the STEPS study

BACKGROUND

The current research aimed to evaluate the relationship between fruit, vegetable (FV), and dairy consumption with the odds of developing hypertension based on nationwide Stepwise approach to surveillance (STEPS) data in Iran.

METHODS

This cross-sectional study was accomplished by the research center of non-communicable diseases (NCDs) in Tehran. In total, 29,378 individuals' data were analyzed. Participants were classified into normal, elevated BP, stage I, and stage II hypertension according to systolic blood pressure (SBP) and diastolic blood pressure (DBP) examinations. Based on the STEPS questionnaire, the consumption of FVs and dairy products was evaluated. Multinomial logistic regression was applied to assess the relationship between the consumption of FVs and dairy products with hypertension.

RESULTS

The findings revealed that only fruit consumption (≥ 2 servings/day) was negatively related to stage I hypertension (odds ratio (OR) = 0.81; 95% confidence interval (CI): 0.69-0.95) in two servings per day and OR = 0.81; 95% CI: 0.68-0.96 in > two servings per day) in the adjusted model. There was no significant relationship between consuming vegetables and dairy products with elevated BP and hypertension.

CONCLUSION

Our study showed that increasing fruit consumption was related to reducing hypertension odds. Regarding the consumption of dairy products and vegetables, no significant relationship was found with the odds of hypertension. More studies, especially cohorts, are needed to evaluate the impacts of FV and dairy products on the risk of hypertension.

No adverse effects of dairy products on lipid profile: A systematic review and meta-analysis of randomized controlled clinical trials

BACKGROUND AND AIMS

The current study aimed to review the effects of dairy foods on lipid profile in randomized controlled clinical trials (RCTs).

METHODS

We searched PubMed, Scopus, Embase, and Central. RCTs that assess the effects of dairy foods on lipid profile were included.

RESULTS

The overall effects of dairy foods on lipid profile were non-significant. Dairy foods were associated with a non-significant reduction in triacylglycerol level, and a non-significant increase in total cholesterol, low density lipoprotein cholesterol, and high-density lipoprotein cholesterol level.

CONCLUSION

We conclude that dairy foods doesn't have any unfavorable effects on lipids.

The effect of dietary nitrate and vitamin C on endothelial function, oxidative stress and blood lipids in untreated hypercholesterolemic subjects: A randomized double-blind crossover study

BACKGROUND

Vitamin C may enhance nitric oxide (NO) production through stepwise reduction of dietary nitrate (NO₃) to nitrite (NO₂) to NO. The combined effect of vitamin C and NO₃ supplementation is relatively unexplored in untreated hypercholesterolemia.

AIMS

We aimed to examine whether co-administration of vitamin C and nitrate for 4-weeks would improve endothelial function (primary outcome), plasma NO metabolites, oxidative stress, and blood lipids (secondary outcomes).

METHODS

Subjects 50-70 years of age with low density lipoprotein (LDL) > 130 mg/dL and RHI ≤2 were enrolled in this randomized double-blind crossover study. Subjects were assigned to two 4-week supplementation treatments starting with 70 ml of concentrated beetroot juice (CBJ) with 1000 mg of vitamin C (NC) or CBJ with matched placebo (N), then switched to alternate treatment following 2-week washout. The change in reactive hyperemia index (RHI), sum of plasma NO metabolites (NO₂ + NO₃ (NOx)), oxidized LDL (oxLDL), and serum lipids were assessed at baseline and at 4-weeks of each treatment period.

RESULTS

Eighteen subjects (11M:7F) completed all study visits. No significant treatment differences were observed in RHI change (N: 0.21 ± 0.12; NC: 0.20 ± 0.17; p = 0.99). Secondary analysis revealed that a subgroup of NC subjects who started with a baseline RHI of <1.67 (threshold value for ED) had greater improvements in RHI compared to subjects with RHI >1.67 (1.23 ± 0.15 to 1.96 ± 0.19; n = 8 vs. 1.75 ± 0.11 to 1.43 ± 0.10; n = 8; p = 0.02). Compared to N, NC experienced a significant increase in plasma NOx (N: 94.2 ± 15.5 μmol/L; NC: 128.7 ± 29.1 μmol/L; p = 0.01). Although there was no significant difference in oxLDL change between treatments (N: -1.08 ± 9.8 U/L; NC: -6.07 ± 9.14 U/L; p = 0.19), NC elicited significant reductions in LDL (N: 2.2 ± 2; NC: -10.7 ± 23; p = 0.049), triglycerides (N: 14.6 ± 43; NC: -43.7 ± 45; p = 0.03), and no change in serum high density lipoprotein. Within treatment group comparisons showed that only NC reduced oxLDL significantly from baseline to 4 weeks (p = 0.01).

CONCLUSIONS

No between intervention differences were observed in RHI. RHI only improved in NC subjects with ED at intervention baseline. Four weeks of NC enriched the NO pool and promoted reduction of blood lipids and oxidative stress in subjects with hypercholesterolemia. These preliminary findings highlight a supplementation strategy that may reduce the progression of atherosclerotic disease and deserves further attention in studies using flow mediated dilation methods.

CLINICAL TRIAL REGISTRATION

www.clinicaltrials.gov (NCT04283630).

Effects of a High-Protein Diet on Cardiometabolic Health, Vascular Function, and Endocannabinoids-A PREVIEW Study

An unfavorable lipid profile and being overweight are known mediators in the development of cardiovascular disease (CVD) risk. The effect of diet, particularly high in protein, remains under discussion. Therefore, this study examines the effects of a high-protein (HP) diet on cardiometabolic health and vascular function (i.e., endothelial function, arterial stiffness, and retinal microvascular structure), and the possible association with plasma endocannabinoids and endocannabinoid-related compounds in overweight participants. Thirty-eight participants (64.5 ± 5.9 (mean ± SD) years; body mass index (BMI) 28.9 ± 4.0 kg/m²) were measured for 48 h in a respiration chamber after body-weight maintenance for approximately 34 months following weight reduction. Diets with either a HP (n = 20) or moderate protein (MP; n = 18) content (25%/45%/30% vs. 15%/55%/30% protein/carbohydrate/fat) were provided in energy balance. Validated markers for cardiometabolic health (i.e., office blood pressure (BP) and serum lipoprotein concentrations) and vascular function (i.e., brachial artery flow-mediated vasodilation, pulse wave analysis and velocity, and retinal microvascular calibers) were measured before and after those 48 h. Additionally, 24 h ambulatory BP, plasma anandamide (AEA), 2-arachidonoylglycerol (2-AG), oleoylethanolamide (OEA), palmitoylethanolamide (PEA), and pregnenolone (PREG) were analyzed throughout the day. Office and ambulatory BP, serum lipoprotein concentrations, and vascular function markers were not different between the groups. Only heart rate (HR) was higher in the HP group. HR was positively associated with OEA, while OEA and PEA were also positively associated with total cholesterol (TC) and low-density lipoprotein (LDL) cholesterol concentrations. Vascular function markers were not associated with endocannabinoids (or endocannabinoid-related substances). In conclusion, the HP diet did not affect cardiometabolic health and vascular function in overweight participants after completing a weight-loss intervention. Furthermore, our data indicate a possible association between OEA and PEA with TC and LDL cholesterol.

Dairy Consumption in Relation to Hypertension Among a Large Population of University Students: The MEPHASOUS Study

BACKGROUND

Hypertension is a chronic condition that its prevalence is increasing at an alarming rate. Findings on the association between dairy consumption and hypertension are conflicting and few data are available in the Middle East.

AIM

To assess the association between dairy consumption and hypertension among a large population of university students.

MATERIALS AND METHODS

The current study was performed in the framework of the Mental and Physical Health Assessment of University Student (MEPHASOUS) project. Overall, 67,011 university students with complete information were included in the statistical analysis. To assess dairy consumption, a self-administered dietary habits questionnaire was employed. Blood pressure was measured using a standard protocol. The systolic/diastolic blood pressure of ≥140/90 mmHg was considered hypertension.

RESULTS

Hypertension was prevalent among 6.9% of students. A significant inverse association was found between dairy consumption and the odds of hypertension; such that after taking potential confounders into account, individuals in the highest levels of dairy consumption had 85% lower odds for having hypertension compared with those in the lowest levels (odds ratio (OR): 0.15, 95% confidence interval (CI): 0.13-0.18). Such an inverse association was also seen among males (OR: 0.14, 95% CI: 0.11-0.18) and females (OR: 0.16, 95% CI: 0.12-0.21), normal-weight students (OR: 0.15, 95% CI: 0.12-0.18) and those with overweight or obesity (OR: 0.15, 95% CI: 0.11-0.21), and individuals with (OR: 0.13, 95% CI: 0.11-0.16) and without (OR: 0.24, 95% CI: 0.17-0.35) family history of hypertension.

CONCLUSION

Our results support the previous findings on the inverse association between dairy consumption and hypertension among university students.

Milk and Dairy Product Consumption and Cardiovascular Diseases: An Overview of Systematic Reviews and Meta-Analyses

Milk and dairy products containing milk fat are major food sources of saturated fatty acids, which have been linked to increased risk of cardiovascular-related clinical outcomes such as cardiovascular disease (CVD), coronary heart disease (CHD), and stroke. Therefore, current recommendations by health authorities advise consumption of low-fat or fat-free milk. Today, these recommendations are seriously questioned by meta-analyses of both prospective cohort studies and randomized controlled trials (RCTs) reporting inconsistent results. The present study includes an overview of systematic reviews and meta-analyses of follow-up studies, an overview of meta-analyses involving RCTs, and an update on meta-analyses of RCTs (2013-2018) aiming to synthesize the evidence regarding the influence of dairy product consumption on the risk of major cardiovascular-related outcomes and how various doses of different dairy products affect the responses, as well as on selected biomarkers of cardiovascular disease risk, i.e., blood pressure and blood lipids. The search strategies for both designs were conducted in the MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Web of Science databases from their inception to April 2018. From the 31 full-text articles retrieved for cohort studies, 17 met the eligibility criteria. The pooled risk ratio estimated for the association between the consumption of different dairy products at different dose-responses and cardiovascular outcomes (CVD, CHD, and stroke) showed a statistically significant negative association with RR values <1, or did not find evidence of significant association. The overview of 12 meta-analyses involving RCTs as well as the updated meta-analyses of RCTs did not result in significant changes on risk biomarkers such as systolic and diastolic blood pressure and total cholesterol and LDL cholesterol. Therefore, the present study states that the consumption of total dairy products, with either regular or low fat content, does not adversely affect the risk of CVD.

Association of Dairy Consumption and 24-Hour Blood Pressure in Older Adults with Hypertension

BACKGROUND

The aim was to examine the association between habitual consumption of dairy products and 24-hour ambulatory blood pressure monitoring among older adults with hypertension.

METHODS

We conducted an analysis of 715 community-living hypertensive adults age ≥60. Habitual dairy consumption was assessed with a validated diet history. Blood pressure was recorded by 24-hour ambulatory blood pressure monitoring; controlled blood pressure was defined as 24-hour blood pressure <130/80mm Hg in those under drug treatment. Analyses were adjusted for main confounders, including diet, hypertension duration, and being on antihypertensive treatment.

RESULTS

After adjustment for confounders, consumers of ≥7 servings/week of whole-fat milk/yogurt had a diastolic blood pressure 1.40mm Hg higher (95% confidence interval, 0.01, 2.81) than consumers of <1 serving/week. By contrast, consumers of ≥7 servings/week of low-fat milk/yogurt had a diastolic blood pressure 1.74mm Hg lower (95% confidence interval, -3.26, -0.23) than consumers of <1 serving/week. Moreover, the odds ratio (95% confidence interval) for controlled blood pressure was 1.83 (1.05-3.08) for those consuming ≥7 servings/week of low-fat milk/yogurt, when compared with consumers of <1 serving/week. Cheese consumption was not associated with blood pressure.

CONCLUSIONS

Regular consumption of low-fat milk/yogurt was associated with lower 24-hour diastolic blood pressure and with better blood pressure control among older adults with hypertension.

Effects of Yogurt and Yogurt Plus Shallot Consumption on Lipid Profiles in Type 2 Diabetic Women

Background:

Identification of food with lowering cholesterol level properties plays a vital role to control impaired lipid profile among type 2 diabetic patients. the current study aimed to evaluate the effects of yogurt and yogurt plus shallot intake on lipid profiles in type 2 diabetic women.

Methods:

Forty-eight participants with type 2 diabetes were enrolled in this study. Participants in the first group (n = 22) received 150 ml of low-fat yogurt (1.5% fat) and those in the second group (n = 26) received 150 ml of low-fat yogurt (1.5% fat) plus shallot for 10 weeks. Serum triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC) concentrations, and fasting blood sugar (FBS) were measured before and after each intervention.

Results:

comparison of parameters between two groups after intervention showed that TG and TC concentrations decreased more in participants who consumed yogurt plus shallot than who consumed yogurt (P = 0.003 and P = 0.04, respectively), also LDL-C level of participants who were in yogurt plus shallot group was lower than that of participants in yogurt group, but this difference was marginally significant (P = 0.06). However, FBS level was not statistically different between two groups.

Conclusions:

This study found that yogurt plus shallot intake significantly decreased LDL-C, TG, and TC levels in diabetic women compared with yogurt intake.

Comprehensive Review of the Impact of Dairy Foods and Dairy Fat on Cardiometabolic Risk

Because regular-fat dairy products are a major source of cholesterol-raising saturated fatty acids (SFAs), current US and Canadian dietary guidelines for cardiovascular health recommend the consumption of low-fat dairy products. Yet, numerous randomized controlled trials (RCTs) have reported rather mixed effects of reduced- and regular-fat dairy consumption on blood lipid concentrations and on many other cardiometabolic disease risk factors, such as blood pressure and inflammation markers. Thus, the focus on low-fat dairy in current dietary guidelines is being challenged, creating confusion within health professional circles and the public. This narrative review provides perspective on the research pertaining to the impact of dairy consumption and dairy fat on traditional and emerging cardiometabolic disease risk factors. This comprehensive assessment of evidence from RCTs suggests that there is no apparent risk of potential harmful effects of dairy consumption, irrespective of the content of dairy fat, on a large array of cardiometabolic variables, including lipid-related risk factors, blood pressure, inflammation, insulin resistance, and vascular function. This suggests that the purported detrimental effects of SFAs on cardiometabolic health may in fact be nullified when they are consumed as part of complex food matrices such as those in cheese and other dairy foods. Thus, the focus on low-fat dairy products in current guidelines apparently is not entirely supported by the existing literature and may need to be revisited on the basis of this evidence. Future studies addressing key research gaps in this area will be extremely informative to better appreciate the impact of dairy food matrices, as well as dairy fat specifically, on cardiometabolic health.

Dairy food products: good or bad for cardiometabolic disease?

Prevalence of type 2 diabetes mellitus (T2DM) is rapidly increasingly and is a key risk for CVD development, now recognised as the leading cause of death globally. Dietary strategies to reduce CVD development include reduction of saturated fat intake. Milk and dairy products are the largest contributors to dietary saturated fats in the UK and reduced consumption is often recommended as a strategy for risk reduction. However, overall evidence from prospective cohort studies does not confirm a detrimental association between dairy product consumption and CVD risk. The present review critically evaluates the current evidence on the association between milk and dairy products and risk of CVD, T2DM and the metabolic syndrome (collectively, cardiometabolic disease). The effects of total and individual dairy foods on cardiometabolic risk factors and new information on the effects of the food matrix on reducing fat digestion are also reviewed. It is concluded that a policy to lower SFA intake by reducing dairy food consumption to reduce cardiometabolic disease risk is likely to have limited or possibly negative effects. There remain many uncertainties, including differential effects of different dairy products and those of differing fat content. Focused and suitably designed and powered studies are needed to provide clearer evidence not only of the mechanisms involved, but how they may be beneficially influenced during milk production and processing.

New perspectives on dairy and cardiovascular health

CVD are the leading cause of mortality and morbidity worldwide. One of the key dietary recommendations for CVD prevention is reduction of saturated fat intake. Yet, despite milk and dairy foods contributing on average 27 % of saturated fat intake in the UK diet, evidence from prospective cohort studies does not support a detrimental effect of milk and dairy foods on risk of CVD. The present paper provides a brief overview of the role of milk and dairy products in the diets of UK adults, and will summarise the evidence in relation to the effects of milk and dairy consumption on CVD risk factors and mortality. The majority of prospective studies and meta-analyses examining the relationship between milk and dairy product consumption and risk of CVD show that milk and dairy products, excluding butter, are not associated with detrimental effects on CVD mortality or risk biomarkers that include serum LDL-cholesterol. In addition, there is increasing evidence that milk and dairy products are associated with lower blood pressure and arterial stiffness. These apparent benefits of milk and dairy foods have been attributed to their unique nutritional composition, and suggest that the elimination of milk and dairy may not be the optimum strategy for CVD risk reduction.

The Effect of Protocatechuic Acid on Blood Pressure and Oxidative Stress in Glucocorticoid-induced Hypertension in Rat

Oxidative stress is one of the important mechanisms involved in Dexamethasone (Dex)-induced hypertension. Protocatechuic acid (PCA) is a natural compound with high antioxidant capacity. In this investigation, the effect of pretreatment with PCA was studied in Dex-induced hypertensive male Wistar rats. For induction of hypertension, Dex was injected subcutaneously for 14 days. PCA (50, 100 and 200 mg/kg) was started from 4 days before Dex administration and continued during the test period. Systolic blood pressure (SBP) was recorded using tail-cuff method. Measurement of thymus weight was done as a marker of glucocorticoid activity. The hydrogen peroxide (H₂O₂) concentration and ferric reducing antioxidant power (FRAP) were determined in plasma samples. Significant increase in SBP and plasma H₂O₂ concentration and decrease in FRAP value and in the body and thymus weights were observed in Dex-induced hypertensive rats. PCA dose-dependently prevented hypertension and body weight loss, and reduced plasma H₂O₂ concentration and increased FRAP values. These results suggest the antihypertensive and antioxidant effects of PCA against Dex-induced hypertension.

Dairy: A lower percent investment in the volatile hypertensive environment

In cross-sectional and intervention studies, low-fat dairy has proven to be effective in lowering blood pressure in a hypertensive population. Contributing mechanisms include the angiotensin-converting enzyme-inhibiting effects of peptides and possible interplay between calcium and vitamin D. Easily added to the diet, low-fat dairy is an attractive addition to nutritional, lifestyle, and pharmacological interventions to treat hypertension.