The role of nutrition in the prevention and treatment of hypertension

Effects of milk proteins on blood pressure: a meta-analysis of randomized control trials

Certain foods or their components are widely used in the prevention and/or management of cardiovascular disease. Milk proteins have been suggested to have hypotensive properties. A number of clinical trials have been carried out to evaluate the effect of milk proteins from whole foods and supplements on blood pressure (BP). However, the effect of milk proteins on BP is not well understood. Therefore, we conducted a meta-analysis of randomized control trials to provide insight into and robust evidence concerning the overall impact of milk proteins on BP. The PubMed and Cochrane databases were searched for literature concerning the effects of milk proteins on BP up to May 2016. A random effects model was used to calculate the pooled estimates and 95% confidence intervals of effect sizes. The final analysis included seven randomized control trials involving 412 participants. Overall, milk protein interventions significantly lowered systolic BP by -3.33 mm Hg (95% confidence interval -5.62, -1.03) and diastolic BP by -1.08 mm Hg (95% confidence interval -3.38, -0.22). There was no statistical evidence of publication bias across the studies. In conclusion, this meta-analysis provides further evidence that milk proteins slightly but significantly lower both systolic and diastolic BP.

Independent contribution of dairy products and calcium intake to blood pressure variations at a population level

PURPOSE

Previous studies have shown a potential inverse relationship between blood pressure and daily calcium intake. The aim of the study was to assess the independent contribution of dairy product and calcium intake to blood pressure variations at a population level.

METHODS

A sample of 912 men aged 45-64 years was randomly selected from the general population, as part of the French MONICA cross-sectional survey on cardiovascular risk factors (1995-1996). Extensive questionnaires on risk factors were filled out and each participant completed a three-consecutive-day food record. Two blood pressure measurements were performed at rest. In statistical analyses subjects were grouped according to quintiles of dairy product or calcium intakes.

RESULTS

Systolic and diastolic blood pressures significantly decreased from the lowest [145.4 (standard error (SE) 1.55) and 89.0 (SE 0.94) mmHg respectively] to the highest quintile [135.6 (SE 1.26) and 85.3 (SE 0.84) mmHg respectively] of dairy product intakes in bivariate analysis. After multivariate linear regression analysis adjusted for confounders [centre, age, daily sodium, magnesium, calcium and alcohol intake, daily energy intake without alcohol, dieting, physical activity, body mass index (BMI), smoking, and use of antihypertensive or lipid-lowering drugs], the difference in systolic blood pressure remained significant. Results were similar when calcium intake was considered. After adjustment for confounders, the association between calcium-dairy product combination and blood pressure was the most significant when intakes of dairy products and calcium were both higher than the median.

CONCLUSION

Dairy products and dietary calcium are both significantly and independently associated with low levels of systolic blood pressure.

Omega-3 fatty acids improve glucose tolerance and components of the metabolic syndrome in Alaskan Eskimos: the Alaska Siberia project

OBJECTIVES

To test the hypothesis that the unusually low prevalences of insulin resistance (IR), metabolic syndrome (MS) and diabetes (DM) in Alaskan Eskimos, compared to American Indians, is related to the traditional Eskimo diet, high in C20-C22 omega-3 fatty acids (FAs). To determine if the relatively low blood pressures, low serum triglycerides and high HDL cholesterol levels in Eskimos result from high omega-3 FA consumption.

STUDY DESIGN

Cross-sectional study.

METHODS

We measured plasma FA concentrations in 447 Norton Sound Eskimos (35-74 years of age) and screened for DM, CHD and associated risk factors. A dietary assessment (24-hr recall) was obtained for comparison the day before the blood sampling.

RESULTS

Plasma omega-3 FA concentrations were highly correlated with dietary omega-3 FAs and HDL levels and inversely correlated with plasma levels of insulin, 2-h insulin (OGTT), HOMI-IR, 2-h glucose (OGTT), triglyceride levels and diastolic blood pressure.

CONCLUSIONS

High consumption of omega-3 FAs positively affects components of the MS, insulin sensitivity and glucose tolerance. This finding suggests that high consumption of C20-C22 omega-3 FAs protects against the development of the MS and glucose intolerance.

Effect of ingesting sour milk fermented using Lactobacillus helveticus bacteria producing tripeptides on blood pressure in subjects with mild hypertension

Angiotensin-converting enzyme (ACE) is important in the regulation of blood pressure (BP). Two tripeptides that inhibit ACE, isoleucyl-prolyl-proline (Ile-Pro-Pro) and valyl-prolyl-proline (Val-Pro-Pro), have been isolated from certain sour milks. The aim of the study reported was to evaluate the effect on BP in subjects with mild hypertension of a new sour milk containing tripeptides. The initial number of subjects was 60 (36 men, 24 women). Among the criteria for inclusion in the study were systolic BP (SBP) between 140 and 180 mmHg and/or diastolic BP (DPB) between 90 and 110 mmHg, without antihypertensive drug therapy. There were two study periods with a washout period between. All subjects were given 1.5 dl per day of a placebo (regular sour milk) or of the active product, a milk that had been fermented with Lactobacillus helveticus bacteria and contained 2.4-2.7 mg of Ile-Pro-Pro and 2.4-2.7 mg of Val-Pro-Pro per 1.5 dl. In the first phase, SBP fell 16 mmHg from baseline in the active group, 2 mmHg more than in the placebo group (P=0.0668) and no difference in DBP (P=0.92). There was a statistically significant downward trend both in SBP and DBP (P=0.0001). During the second phase, SBP fell 11 mmHg in the active group (P=0.008). The reduction in SBP was significantly larger in active than placebo group (P=0.012). In the crossover analysis combining both phases, SBP fell on average 2.6+/-15.9 mmHg more on the active product compared with the placebo product, but this difference was not statistically significant (P=0.3111). The difference in DBP, 1.0+/-8.3 mmHg between the two test products was not significant either (P=0.4431). In conclusion, the ingestion of sour milk fermented by L. helveticus bacteria and that containing ACE inhibitory tripeptides seems to lower BP modestly.

Dietary and other non-pharmacological treatments in patients with drug-treated hypertension and control subjects

OBJECTIVE

To study the nutrient intakes and other lifestyle patterns of drug-treated hypertensives and control subjects.

DESIGN

A cross-sectional population-based epidemiological study.

SETTING

The participating study subjects visited the research laboratory of the Department of Internal Medicine of the University of Oulu, Oulu, Finland.

PARTICIPANTS

A total of 1045 Finnish men and women aged 40-60 years, of whom 716 (69%) completed 7-day food records.

MAIN OUTCOME MEASURES

Intakes of energy, protein, total fat, saturated, monounsaturated and polyunsaturated fatty acids, carbohydrate, alcohol, fibre, calcium, magnesium, potassium and sodium were assessed from 7-day food records. The study also included measurements of blood pressure, blood glucose and plasma lipids, and anthropometric variables. Information about alcohol consumption, smoking habits and physical activity was collected by interviewing.

RESULTS

Obesity was common amongst the hypertensive subjects, whose body mass indices were significantly higher than those of the control subjects. Only minor differences existed in the energy intake levels and nutrient intakes of the hypertensive and control cohorts, but the control subjects performed more physical activity than the hypertensive subjects. The dietary recommendations concerning the intakes of total and saturated fats, carbohydrate and fibre were poorly met by both the hypertensive and the control subjects. Alcohol consumption was high amongst the hypertensive men, especially amongst the smokers.

CONCLUSIONS

Non-pharmacological treatment, including dietary management, of hypertensive patients at high risk for cardiovascular complications seems still to be inadequate. Additional well-focused efforts are needed to intensify the dietary treatment as well as to reduce alcohol consumption and smoking amongst hypertensives.

Use of dietetic-specific nutritional diagnostic codes in clinical reasoning relevant to the nutritional management of core clinical outcome indicators in hemodialysis patients

The Health Care Financing Agency (HCFA) has recommended conscientious monitoring of four core outcome indicators (anemia, albumin, treatment adequacy, and hypertension) by the end stage renal disease (ESRD) health care team. Dietetic-specific nutritional diagnostic categories (D-S NDCs) can be a powerful tool in guiding renal nutrition specialists through the clinical reasoning required to diagnose and clinically correct nutrition-related problems in hemodialysis (HD) patients. The purpose of this article is to portray one clinician's dual use of D-S NDCs to identify the nutritional problem responsible for poor performance and determine nutritionally treatable causes. Although four indicator-specific sets of D-S NDCs commonly used in the nutritional assessment of anemia, albumin, treatment adequacy and hypertension were identified and referenced, seven codes were consistently repeated. These D-S NDCs were (1) altered nutritional biochemistry integrity; (2) absence of/limited nutritional service; (3) deficit in nutrition knowledge; (4) imbalance of nutrient/fluid; (5) nutrition misinformation; (6) toxicity of nutrient/nutrient end-product; and (7) possibility of developing a specific disease. Thus, in ESRD, use of D-S NDCs shows the implicit role of the registered dietitian in disease prevention, management of altered nutrient disposition, and patient education.

Dietary fat and blood pressure

Both animal and human data suggest that polyunsaturated fatty acids of n-6 and n-3 series may play a role in blood pressure regulation. The majority of dietary intervention studies have shown that changing from a high fat, low linoleic acid diet to a low fat, high linoleic acid diet lowers blood pressure. However, controlled, double-bind studies do not support the independent effect of linoleic acid. Polyunsaturated n-3 fish fatty acids lower blood pressure but only in pharmacological doses that cannot generally be recommended. The mechanisms of blood pressure regulation by n-6 and n-3 fatty acids seem to be related to prostaglandin metabolism.