What Does Eating Plants Do For Hypertension? (Part Two)

Lifestyle can lower blood pressure

Hypertension is a much studied subject and a wealth of information spanning decades gives clear evidence about the effect of food on high blood pressure. Here is some of what the science says.

1974: Sacks, F.M., Rosner, B., Kass, E.H. Blood pressure in vegetarians. Am J Epidemiol. 1974 Nov; 100(5):390-398.
In this study, vegetarians who avoided the most animal proteins had lower blood pressure.

1983: Rouse, I.L, Beilin, L.J., Armstrong, B.K., Vandongen, R. Blood-pressure-lowering effect of a vegetarian diet: controlled trial in normotensive subjects. Lancet. 1983 Jan 1; 1(8314-5): 5 -10.
This randomized controlled trial saw a significant fall in systolic and diastolic blood pressure in the experimental group while they were eating a vegetarian diet. Once they were reverted to an omnivorous diet their blood pressure rose. This study controlled for body weight, sodium intake and potassium intake.

1986: Margetts, B.M., Beilin, L.J. et al. Vegetarian diet in mild hypertension: a randomized controlled trial. Br Med J (Clin Res Ed). 1986 Dec 6; 293(6560): 1468–1471.
This study saw a fall in systolic blood pressure while subjects ate a vegetarian diet with a corresponding rise on the resumption of eating meat. The study controlled for body weight and sodium intake.

2002: Stamler,J., Liu, K. et al. Eight-year blood pressure change in middle-aged men: relationship to multiple nutrients. Hypertension. 2002 May; 39(5):1000-1006.
This study looked at the relationship between nutrients, alcohol intake, and change in weight to the change in blood pressure over eight years. Results showed that the more animal protein and the more fat people ate, the higher their risk for developing hypertension. Also, the consumption of plant proteins actually lowered blood pressure.

2002: Appleby, P.N., Davey, G.K., Key, T.J. Hypertension and blood pressure among meat eaters, fish eaters, vegetarians and vegans in EPIC-Oxford. Public Health Nutr. 2002 Oct; 5(5):645-654.
This study compared hypertension in four different diet groups. Over 11,000 men and women took part. It was found that non-meat eaters, especially vegans, had a lower prevalence of hypertension and lower systolic and diastolic blood pressures than meat eaters. Some of this difference was due to differences in body mass but, after adjustment, even unhealthy vegetarians had significantly lower blood pressure than healthy meat eaters.

2002: John, J.H., Ziebland, S., et al. Effects of fruit and vegetable consumption on plasma antioxidant concentrations and blood pressure: a randomised controlled trial. Lancet. 2002 Jun 8; 359(9322): 1969-1974.
Participants in the intervention group of this study were encouraged to increase their consumption of fruit and vegetables to at least five portions a day. Both systolic and diastolic pressure decreased further in the intervention group than in the control group.

2003: Appel, J.J., Champagne, C.M., Harsha, D.W. et al. Effects of comprehensive lifestyle modification on blood pressure control: main results of the PREMIER clinical trial. JAMA. 2003 Apr 23-30; 289(16):2083-2093.
This was a randomized controlled trial that looked into the simultaneous implementation of five lifestyle changes and their effect on blood pressure. The five changes were eating the DASH diet, losing weight, reducing sodium, increasing physical activity and limiting alcohol intake. The results showed significant blood pressure lowering effects in both systolic and diastolic blood pressure. These lifestyle changes cut the prevalence of hypertension by 65%.

2006: Elliott, P., Stamler,J., Dyer, A.R. et al. Association between protein intake and blood pressure. The INTERMAP Study. Arch Intern Med 2006; 166(1): 79-87.
This study included 4,680 people and found that vegetable protein has a significant blood-pressure-lowering effect.

2007: Fontana, L., Meyer, T.E., Klein, S., Holloszy, J.O. Long-term low-calorie low-protein vegan diet and endurance exercise are associated with low cardiometabolic risk. Rejuvenation Res. 2007 Jun; 10(2): 225-234.
This study compared three groups of people;
1-Omnivorous long-distance endurance athletes who had run on average of 75 km/week for 21 years
2-Sedentary meat eaters who exercised less than an hour per week
3-Sedentary vegans who ate unprocessed plant foods.
Results showed that endurance runners had better blood pressure on average than the sedentary meat-eaters (122/72 compared to 132/79). However, vegans, even though they did not exercise, had the lowest blood pressure of all groups – an average of 104/62. The conclusion was that specific components of a low-calorie low-protein vegan diet provide additional beneficial effects on blood pressure.

2008: Wang, Y.F., Yancy, W.S., Yu, D. et al. The relationship between dietary protein intake and blood pressure: results from the PREMIER study. J Hum Hypertens. 2008 Nov; 22 (11):745-754.
This was a randomized trial that examined the association of protein intake with blood pressure and in particular the relationship of plant and animal protein with blood pressure. Results found that both fruit and vegetable intake and specifically dietary plant protein intake were associated with a reduction of systolic and diastolic blood pressure. Researchers concluded that increased intake of plant protein is a useful means to prevent and treat hypertension.

2009: Stamler,J., Brown, I.J. ,Daviglus, M.L. et al. INTERMAP Research Group 2009. Glutamic acid, the main dietary amino acid, and blood pressure: The INTERMAP Study. Circulation 2009; 120(3); 221-228.
This was a follow-up study to the 2006 INTERMAP study. The reason for the beneficial effect of vegetable protein on blood pressure was suspected to be the higher amount of glutamic acid in the diet of people eating plants. Glutamic acid is an amino acid found in much higher quantities in plants than animals. Glutamic acid is converted to glutathione, a very potent antioxidant. The conclusion was that dietary glutamic acid may have independent blood pressure-lowering effects, which may contribute to the inverse relation of vegetable protein to blood pressure.

2012: Pettersen, B.J., Anousheh, R. et al. Vegetarian diets and blood pressure among white subjects: results from the Adventist Health Study-2 (AHS-2). Public Health Nutr. 2012 Oct; 15(10):1909-1916.
This study compared healthy meat eaters to vegetarians and vegans who ate no animal proteins. The resulting risk of having hypertension compared to omnivores was;
Vegans – 63% lower risk of hypertension
Lacto-ovo vegetarians – 43% lower risk of hypertension
Partial vegetarians – 8% lower risk of hypertension
The study was adjusted for effects from BMI.

2014: Yokoyama, Y., Nishimura, K., Barnard, N.D., Takegami, M., et al. Vegetarian diets and blood pressure: a meta-analysis. JAMA Intern Med. 2014 Apr; 174(4):577-587.
The purpose of this study was to conduct a systematic review and meta-analysis of controlled clinical trials and observational studies that examined the association between vegetarian diets and blood pressure. Seven clinical trials and 32 observational studies were included in this analysis. The results showed that people eating vegetarian diets had significantly lower blood pressures than those on omnivorous diets.

 

On top of the blood lowering strength of fruits and vegetables, here are some specific foods and activities that can reduce blood pressure…

HIBISCUS TEA
McKay, D.L., Chen, C.Y., Saltzman, E. et al. Hibiscus sabdariffa L. tea (tisane) lowers blood pressure in prehypertensive and mildly hypertensive adults. J Nutr. 2010; 140(2): 298-303.
This study from Tufts University was double-blind and placebo-controlled. It compared hibiscus tea with an artificially coloured and flavoured lookalike. Three cups of hibiscus tea a day significantly lowered systolic blood pressure by 6 points over the control group.

Hopkins, A.L., Lamm, M.G., Funk, J.L, Ritenbaugh, C. Hibiscus sabdariffa L. in the treatment of hypertension and hyperlidemia: a comprehensive review of animal and human studies. Fitoterapia. 2013; 85: 84-94.
This review of many studies corroborated the findings that hibiscus tea lowers blood pressure significantly.

GRAINS
Tighe, P., Duthie, G., Vaughan, N. et al. Effect of increased consumption of whole-grain food on blood pressure and other cardiovascular risk markers in healthy middle-aged persons: a randomized controlled trial. Am J Clin Nutr. 2010; 92(4)733-740.
Eating three portions of whole grains a day reduces blood pressure enough to decrease the risk of heart attack by 15% and the risk of stroke by 25%. This is the same blood pressure lowering benefit offered by blood pressure medications but without the adverse side effects. The side effects of eating grains are positive ones – lower risk of type 2 diabetes, coronary heart disease, weight gain and colon cancer. Refined grains have the opposite effect, increasing both blood pressure and the risk of type 2 diabetes (1).

FIBER
Whelton, A.D., Hyre, B., Pedersen, Y., et al. Effect of dietary fiber intake on blood pressure: a meta-analysis of randomized, controlled clinical trials. Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet].Pub Med Health 2005.
This review assessed the effect of dietary fibre on blood-pressure and concluded that increased consumption of dietary fibre can reduce blood pressure in patients with hypertension. A smaller reduction in blood pressure was also observed in patients with normal blood pressure. Fiber seems to be independently associated with the lowering of blood pressure. Fiber comes only from plants.

EXERCISE
Cornelissen, V.A., Buys, R., Smart, N.A. Endurance exercise beneficially affects ambulatory blood pressure: a systematic review and meta-analysis. J Hypertension. 2013; 31(4): 639-648.
Randomized controlled trials illustrate the effect of aerobic endurance training. Overall, endurance training induced a significant reduction in daytime systolic and diastolic blood pressure.

FLAXSEED
Rodriguez-Leyva, D., Weighell, W., Edel, A.L. et al. Potent antihypertensive actions of dietary flaxseed in hypertensive patients. Hypertension. 2013; 62(6): 1081-1089.
Eating just a few tablespoonful of ground flaxseeds a day results in up to a 15 point drop in systolic blood pressure and a 7 point drop in diastolic blood pressure. This blood pressure lowering effect is 2 to 3 times more powerful than that of adopting an endurance exercise program.

LEGUMES
Jayalath, V.H., de Suza, R.J., Sievenpiper, J.L. et al. Effect of dietary pulses on blood pressure: a systematic review and meta-analysis of controlled feeding trials. Am J Hypertens. 2014; 27(1): 56-64.
Dietary pulses (beans, lentils, chickpeas) significantly lower blood pressure in people with and without hypertension.

ALCOHOL
Chiva-Blanch, G., Urpi-Sarda, M., Ros, E. et al. Dealcoholized red wine decreases systolic and diastolic blood pressure and increases plasma nitric oxide: short communication. Circ Res. 2012; 111(8): 1065-1068.
The aim here was to evaluate the effects of red wine, both alcoholic and non-alcoholic on blood pressure. Results showed that both systolic and diastolic blood pressure decreased significantly after the dealcoholized red wine. There was no significant blood pressure effect from the alcoholic wine.

 

SOURCE;

1 Sun, Q., Spiegelman, D., van Dam, R.M. et al. White rice, brown rice, and risk of type 2 diabetes in US men and women. Arch Intern Med. 2010; 170(11): 969-969.