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Back to Hypertension

Hypertension: Summary of Evidence

Data from several studies, including two systematic reviews and the landmark DASH diet study, have consistently demonstrated a significant benefit from an adequate intake of milk and milk products in the prevention and management of hypertension.

Highlights

  • Total intake of milk products, including milk, yogurt and cheese, may be protective against elevated blood pressure;
  • The consumption of milk, yogurt and low-fat dairy products has been significantly associated with a reduced risk of hypertension;
  • There is no association between the consumption of high-fat dairy products and cheese and hypertension.

Introduction

Evidence from emerging studies indicates that the consumption of milk products has a beneficial effect on blood pressure. Hypertension Canada recommends the DASH diet for the prevention and management of high blood pressure in at-risk individuals. The potential mechanisms by which milk products may modulate blood pressure need to be elucidated, but there is evidence that several components of milk products may be involved, including:

  • Calcium,
  • Vitamin D,
  • Magnesium,
  • Potassium,
  • Phosphorous,
  • Milk proteins and bioactive peptides.

The Evidence

A recent 2012 dose-response meta-analysis of prospective cohort studies was conducted to examine the consumption of total dairy, low-fat dairy, high-fat dairy, and different types of dairy products in relation to hypertension incidence in the general population. This study included 57,256 adults aged 25 to 65 years and follow-up of 5 to 15 years.1

  • The intake of total dairy products (low and high fat) was significantly associated with a risk reduction in hypertension, with a pooled relative risk of 0.97 (95% CI: 0.95-0.99) per 200 g/d;
  • There was a significant inverse linear association between the consumption of milk and incident hypertension, with a pooled relative risk of 0.96 (95% CI: 0.94-0.98) per 200 g/d;
  • Low-fat milk products were inversely associated with hypertension incidence, with a pooled relative risk of 0.96 (95% CI: 0.93-0.99) per intake of 200 g/d;
  • High-fat dairy, total fermented dairy, cheese and yogurt were not significantly associated with hypertension incidence.

Similar findings were observed in another 2012 systematic review and meta-analysis, which included about 45,000 men and women and involved 2 to 15 years of follow-up:2

  • The consumption of total dairy foods (low and high fat) for the highest compared with the lowest intake category was associated with a 13% risk reduction of elevated blood pressure;
  • The consumption of fluid milk products (milk and yogurt, low or full fat) was significantly associated with a reduction in the development of elevated blood pressure, with a relative risk of 0.92 (95% CI: 0.87-0.98);
  • There was a significant association between the consumption of low-fat milk products and a reduced risk of elevated blood pressure, with a relative risk of 0.84 (95% CI: 0.74-0.95);
  • There was no association between the consumption of high-fat milk products and the risk of elevated blood pressure;
  • There was no association between the consumption of cheese and the risk of hypertension.

Another evidence-based systematic review, published by the 2010 Dietary Guidelines Advisory Committee (DGAC), was conducted to examine the effects of milk and milk products on blood pressure. The review included 13 studies, namely 1 systematic review, 1 randomized controlled trial, 6 prospective cohort studies and 5 cross-sectional studies. It was concluded that “a moderate body of evidence suggests an inverse relationship between the intake of milk and milk products and blood pressure.”3

In the landmark randomized controlled Dietary Approaches to Stop Hypertension (DASH) Diet Study, the impact of dietary patterns on blood pressure was examined. After following a control diet for 3 weeks, 459 adults were randomized to 1 of 3 diets as follows:4,5

  • Control diet;
  • Fruits and vegetables diet: 8 to 10 servings per day;
  • Combination (DASH) diet: close to 3 servings of milk products, in addition to the 8 to 10 servings of fruits and vegetables per day.

The milk products in the combination (DASH) diet included about 1 oz of regular-fat cheese.5 It is also important to note that in general, cheese contributes to only about 5% to 8% of total sodium intake.6

For more information on sodium:

Within 2 weeks, both intervention diets significantly lowered blood pressure, with similar reduction patterns observed in men and women and in minorities and non-minorities:

  • The dairy-enriched combination diet (DASH diet) had twice the impact of the fruits and vegetables diet, reducing systolic blood pressure by 5.5 mm Hg and diastolic blood pressure by 3.0 mm Hg (p < 0.001) more than the control diet;
  • About 50% of the magnitude in these reductions could be ascribed to the milk products per se in the diet;5
  • Among hypertensive subjects, the combination DASH diet reduced systolic blood pressure and diastolic blood pressure by 11.4 and 5.5 mm Hg more than the control diet, respectively (p < 0.001), making this diet a viable alternative to monotherapy for mild hypertension;
  • Since weight and sodium intake (3,000 mg) were held constant and alcohol intake was similar in all 3 groups, these well-known confounders did not account for the observed reductions in blood pressure;
  • Reductions in blood pressure of the magnitude achieved by the DASH diet—which is rich in milk products, fruits and vegetables—could translate into a 15% reduction in ischemic heart disease and a 27% reduction in stroke.4

Hypertension Canada recommends the DASH diet for the prevention and management of hypertension in individuals with hypertension and normotensive individuals at increased risk.7 Similarly, in its guidelines for the year 2000, the American Heart Association also recommended the DASH diet for heart health.8 In its 2007 evidence-based guidelines for cardiovascular disease prevention in women, the American Heart Association also recommends an increased consumption of low-fat milk products for optimal blood pressure.9

Potential Mechanisms

Although the mechanisms by which milk products may modulate blood pressure remain to be fully elucidated, calcium is thought to be one of the main nutrients responsible for the impact of milk products on blood pressure control.10

Vitamin D, because of its importance in calcium absorption, may also play a role in the management of blood pressure. Additionally, low vitamin D status has been shown to increase blood pressure by activating the renin-angiotensin-aldosterone system, which leads to vasoconstriction and sodium and water retention.3

Other minerals in milk products, such as magnesium and potassium, may also regulate blood pressure, but their individual contribution is difficult to isolate as they are often found in foods rich in calcium.10

It has also been demonstrated that the intake of milk protein itself may reduce systolic blood pressure in individuals with prehypertension and stage 1 hypertension.11

Bioactive peptides have been shown to have an angiotensin-1-converting enzyme (ACE) inhibitory effect, a key process in blood pressure control.10 Bioactive peptides are formed by either the digestion of casein and whey protein (the main proteins in milk products) or the lactobacilli fermentation of milk (for instance during cheese making). In fact, antihypertensive ACE-inhibitory peptides have been reported to be present in various types of cheese.12

Other studies have shown that certain milk-derived peptide combinations also have hypotensive effects via the modulation of endothelin-1 release by endothelial cells.10 A meta-analysis of milk tripeptides on blood pressure indicated that milk-derived tripeptides have hypotensive effects in individuals with prehypertension and hypertension.13

Conclusions

There is consistent evidence to support a beneficial relationship between milk product consumption and blood pressure control.

The evidence to date indicates that a higher intake of milk products in general (high and low fat), and specifically low-fat milk products and milk, may have a protective role against hypertension. Furthermore, there appears to be a dose-response relationship to this beneficial effect.

There appears to be no association between high-fat milk products and risk of hypertension. With respect to cheese, an increased risk of hypertension is not associated with this milk product even though it contains sodium.

More studies, including randomized controlled trials and mechanistic studies, are needed to provide definitive answers on the role of milk products in the prevention and management of hypertension.

References

  1. Soedamah-Muthu SS et al. Dairy consumption and incidence of hypertension: a dose-response meta-analysis of prospective cohort studies. Hypertension 2012;60(5):1131-7
  2. Ralston RA et al. A systematic review and meta-analysis of elevated blood pressure and consumption of dairy foods. J Hum Hypertens 2012;26(1):3-13.
  3. McGrane MM et al. Dairy consumption, blood pressure, and risk of hypertension: an evidence-based review of recent literature. Curr Cardiovasc Risk Rep 2011;5(4):287-98.
  4. Appel LJ et al. A clinical trial of the effects of dietary patterns on blood pressure. N Eng J Med 1997;336(16):1117-24.
  5. Karanja NM et al. Descriptive characteristics of the dietary patterns used in the Dietary Approaches to Stop Hypertension Trial. J Am Diet Assoc 1999;99(suppl):S19-S27.
  6. López-Expósito I et al. A mini-review on health and nutritional aspects of cheese with a focus on bioactive peptides. Dairy Sci. & Technol 2012;92(5):;419-38.
  7. Khan NA et al. The 2008 Canadian Hypertension Education Program recommendations for the management of hypertension: part 2-therapy.Can J Cardiol 2008;24(6):465-75.
  8. Krause RM et al. AHA dietary guidelines: revision 2000: a statement for healthcare professionals from the Nutrition Committee of the American Heart Association. Circulation 2000;102(18):2284-99.
  9. Mosca L et al. Evidence-based guidelines for cardiovascular disease prevention in women: 2007 update. Circulation 2007;115(11):1481-501.
  10. German JB et al. A reappraisal of the impact of dairy foods and milk fat on cardiovascular disease risk. Eur J Nutr 2009;48(4):191-203.
  11. He J et al. Effect of dietary protein supplementation on blood pressure: a randomized controlled trial. Circulation 211;124(5):589-95.
  12. Choi J et al. Bioactive peptides in dairy products. Int J Dairy Tech 2012;65(1):1-12.
  13. Xu JY et al. Effect of milk tripeptides on blood pressure: a meta-analysis of randomized controlled trials. J Nutr 2008;24(10):933-40.

Keywords: hypertension , blood pressure , dash diet , sodium , american heart association , hypertension canada


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