Library

Online Resources

 

Blood Pressure Management and Supplements

By Yousry Naguib, Ph.D.

Vitamin Retailer magazine, November 2003

As many as 50 million Americans suffer from hypertension, the medical term for high blood pressure. There are two types of high blood pressure: essential (primary) hypertension, and secondary hypertension. Essential hypertension is the most common type of hypertension, which accounts for 90% of all cases of high blood pressure. Genes play a major role in essential hypertension. In secondary hypertension, the cause can be identified and usually is treatable or reversible. A number of factors such as stress or anxiety can cause a temporary increase in blood pressure.

Blood pressure refers to the force of the blood pushing against the walls of arteries of the heart as it flows through them. Arteries are the blood vessels that carry oxygenated blood from the heart to the body’s tissues. The more pressure the blood exerts on the artery walls, the higher the blood pressure will be. When artery walls are relaxed or dilated, the pressure of the blood flowing through them is lower than when the artery walls narrow, or constrict.

The action of the heart contracting is known as the systolic component of blood pressure; the heart resting, filling with blood is known as the diastolic component. When blood pressure is measured, the systolic pressure (upper number) is stated first and the diastolic pressure (lower number) second. Blood pressure is measured in millimeters of mercury (mmHg). A reading of 120/80 mmHg means that the systolic pressure is 120 and diastolic pressure is 80. Blood pressure less than 130/85 mmHg is considered normal; a 140/90 is indicative of early high blood pressure.

Hypertension is usually without symptoms until complications develop. Left untreated, hypertension significantly increases the risk of stroke, heart disease, congestive heart failure, and kidney damage.

High blood pressure can make the artery walls thicken and harden, and hence narrowing the inside of the blood vessels. Cholesterol and fats build up on the walls of damaged arteries make them even narrower. Blood clots can also get trapped in narrowed arteries, blocking the flow of blood. Reduced or blocked blood flow to the heart can cause a heart attack. If an artery to the brain is blocked, a stroke can result. Heart diseases cause 250,000 deaths yearly. The costs for hospital care of patients with heart diseases can be staggering and accounts for nearly 25% of the Medicare budget.

Treatment to lower blood pressure usually includes changes in lifestyle and diet, and taking anti-hypertensive medications.

Drug therapy

Drug treatment of heart disease patients might reduce risk of death. Anti-hypertensive medications are classified into several groups of drugs: diuretics, beta-blockers, calcium channel blockers, angiotensin converting enzyme inhibitors (ACE inhibitors), alpha-blockers, and vasodilators.

Diuretics help the kidneys eliminate excess salt and water from the body’s tissues and the blood. The reduction of fluid dilates the walls of arteries and lowers blood pressure.

Beta-blockers and alpha-blockers lower blood pressure by acting on the nervous system to slow the heart rate and reduce the force of the heart’s contraction.

Calcium-channel blockers reduce the ability of arterial walls to constrict by causing muscles surrounding blood vessels to relax. Muscle cells need calcium to constrict, so reducing their calcium keeps them more relaxed and lowers blood pressure.

ACE inhibitors prevent the formation of a hormone, angiotensin that constricts blood vessels. Vasodilators act directly on arteries to relax their walls so blood can move more easily through them. They lower blood pressure rapidly and are given to patients with dangerously high blood pressure.

Beta-blockers, diuretics, or both are usually the first line of treatment for most physicians. In most patients with hypertension, a combination of 2 drugs will provide better BP control than a single drug alone.

Lifestyle modifications

Dietary measures should be the first-line treatment modality for high-normal blood pressure (130-140/85-90 mmHg). The Dietary Approaches to Stop Hypertension Study (DASH) published in the New England Journal of Medicine (1997) suggested a diet containing grains, vegetables, fruits, low fat or non-fat diary products, fish, lean meats, nuts, seeds, and legumes [1]. The study also suggested restricting sodium intake; exercise regularly, limit alcohol consumption, and refrain from smoking. People with high blood pressure should also maintain healthy weight, relax and reduce stress, maintain adequate intake of dietary potassium, maintain adequate intake of dietary calcium and magnesium, and reduce caffeine (caffeine may raise blood pressure; however, no direct relationship between caffeine intake and hypertension has been found in most diet surveys [2].

Salt (sodium chloride) can raise blood pressure by causing the body to retain water, and causing smooth muscle contraction and constriction of small blood vessels, which is associated with a greater resistance to blood flow. The National Institutes of Health (NIH) advises healthy people to get no more than 2.4 grams of sodium chloride a day; 1.5 grams for those with high blood pressure. Weight loss lowers blood pressure in those who are both overweight and hypertensive [3].

The Mediterranean diet, with its emphasis on fresh fruits and vegetables, whole grains, fish, beans, and olive oil, was dubbed “healthy” after scientists discovered that people who lived along the Mediterranean had appreciably lower incidences of obesity and heart problems.

Calcium / Magnesium

Calcium and magnesium may be helpful only for some people with hypertension. Increasing calcium intake appears to possess a greater blood-lowering effect in hypertensive than individuals with normal blood pressure. A meta-analysis of randomized controlled trials showed that calcium supplementation for at least 2 weeks led to a small reduction in systolic but not diastolic blood pressure in both normotensive and hypertensive people [4,5].

Magnesium helps to reduce elevated blood pressure by relaxing the muscles that control blood vessels, allowing blood to flow more freely. Magnesium-rich foods (whole grains, green leafy vegetables, nuts, seeds, dried peas and beans) may lower blood pressure. Clinical studies show that patients with long-term hypertension have at least a 15% deficit in total magnesium [6]. A meta-analysis of randomized clinical trials showed that that increased intake of magnesium resulted in only small overall reduction in blood pressure in both hypertensive and normotensive persons [7].

Potassium

Potassium is an important dietary electrolyte that helps maintain blood pressure levels. Meta-analysis of clinical trials revealed that potassium supplements in the amount of at least 2.4 g per day lowered blood pressure [8]. The study recommended increasing potassium intake for prevention and treatment of hypertension, especially in those who are unable to reduce their sodium intake. However, large dose of potassium can irritate the stomach, and people on potassium-sparing diuretics should only use potassium under the care of health professional.

L-Arginine

L-Arginine, a naturally occurring amino acid, appears to help people with mild hypertension. The health benefits of arginine are attributed to its conversion to nitric oxide (NO) in cells that line the inside of blood vessels. A 2000 Italian study showed that daily supplementation with L-arginine for one week significantly lowered blood pressure in six healthy volunteers [9]. People taking Viagra or nitroglycrin, which also widen blood vessels, should avoid arginine. The recommended dosage is 1-2 grams three times a day.

Coenzyme Q10 (CoQ10)

CoQ10 deficiency is present in almost 40% of patients with high blood pressure. In one clinical trial, CoQ10 supplementation (50 mg three times per day) was found to lower both systolic and diastolic blood pressure, by about 10 percent, in hypertensive patients after four to twelve weeks [10].

Omega-3 fatty acids (EPA and DHA)

Meta-analysis of 31 clinical trials found that high levels (15 grams per day) of EPA and DHA found in fish oil lowers blood [11]. In one double-blind trial DHA was reported to have greater effects on blood pressure than EPA [12]. Omega-3 fatty acids have the ability to make blood platelets less likely to clump together and form clots that lead to heart attacks. Suggested dose is one gram two to three times daily.

Garlic

Garlic has been shown in several large clinical studies to lower blood pressure in people with hypertension. Garlic inhibits clot formation by making platelets less likely to clump, and it can help lower cholesterol levels and prevent formation of artery-clogging plaques. A meta-analysis study of the effect of garlic on blood pressure suggested that garlic might benefit subjects with mild hypertension, but the evidence is insufficient to support its efficacy in the treatment of hypertension [13].

Hibiscus

Hibiscus sabdariffa L., a rose tea, is used in folk medicines against hypertension.

In one study, 54 patients with moderate essential hypertension were randomly assigned to an experimental (sour tea) or control group. After 12 days of treatment, the experimental group showed an 11.2% lowering of the systolic blood pressure and a 10.7% decrease of diastolic pressure as compared with the first day. The difference between the systolic and diastolic blood pressures of the experimental and control groups was significant. The results of this study support the traditional use of sour tea in lowering high blood pressure [14].

In an animal study, the LD (50) of Hibiscus sabdariffa (Roselle calyx) extract was found to be above 5 g per kilogram. Roselle calyx infusion was found to lower significantly both systolic and diastolic pressure in spontaneously hypertensive and normotensive Wistar-Kyoto rats at tested doses of 500 and 1000 mg per kg body weight [15].

In a most recent study, Hibiscus sabdariffa was shown to lower serum lipids and inhibit the development of atherosclerosis in cholesterol-fed rabbits. New Zealand white rabbits were fed a high cholesterol diet with or without 0.5% or 1% Hibiscus sabdariffa extract (HSE) for 10 weeks. The levels of triglycerides, cholesterol, and LDL-cholesterol were lower in the serum of rabbits fed high cholesterol diet plus HSE than in the serum of rabbits fed high cholesterol diet without HSE. Feeding HSE to rabbits also significantly reduced foam cell formation and significantly reduced severe atherosclerosis in the aorta of rabbits [16].

Hawthorn

Hawthorn (Crataegus) has been used a heart tonic for centuries. Hawthorn is prescribed in Germany for the treatment of congestive hart failure. Studies have found that hawthorn can improve the function of the heart, improve the symptoms of heart failure such as fatigue and shortness of breath [17].

The hypotensive potential of hawthorn extract was investigated in a recent pilot study. Thirty-six mildly hypertensive subjects were randomly assigned to a daily supplement for 10 weeks of either 600 mg magnesium, or 500 mg hawthorn extract, or a combination of 600 mg magnesium and 500 mg hawthorn extract, or a placebo. All treatment groups, including placebo, showed a decline in both systolic and diastolic blood pressure. The hawthorn extract group showed a promising reduction in the diastolic blood pressure at week 10, compared to the other groups [18].

Coleus Forskohlii

Coleus Forskohlii is a member of the mint family, and used extensively for many applications in Ayurvedic medicine. The plant contains the diterpene forskolin, which was shown to activate the enzyme adenosine cyclase in various tissues, which in turn, increases cellular levels of cyclic cAMP (cyclic adenosine monophosphate). This increased cAMP synthesis helps to reduce high blood pressure via relaxation of arterial vascular smooth muscles [19], and to reduce platelet stickiness [20]. Coleus Forskohlii also contains the diterpene coleonol, which has been shown to lower blood pressure in spontaneously hypertensive rats due to relaxation of the muscular smooth muscle [21].

Indian Snakeroot (Rauwolfia)

Rauwolfia root contains many alkaloids, including reserpine, which has been used in treating hypertension. Rauwolfia alkaloids work by controlling nerve impulses along certain nerve pathways, as a result they act on the heart and blood vessels to lower blood pressure. In a controlled intervention trial, 389 subjects with diastolic blood pressure 90-115 mmHg were randomly assigned to either a combination of a diuretic and Rauwolfia serpentina, or a placebo. Diastolic blood pressure was reduced an average of 10 mmHg and systolic pressure by 16 mmHg in the Rauwolfia-group, with no change in the placebo group [22]. Due to possible side effects and its interactions with alcohol and certain drugs such as barbiturates and digitalis, Indian snakeroot should only be taken under supervision of a health care professional.

Stevia

The herb Stevia rebaudiana contains the sweet-tasting glycoside stevioside, which is used as sugar substitute. Animal studies have shown that stevioside can lower blood pressure in spontaneously hypertensive rats (SHR). Stevioside administered intraperitonealy (ip) to normotensive rats (NTR), and SHR was shown to lower blood pressure in a dose (100, 200, and 400 mg per kg) dependent manner. The hypotensive effect of stevioside was more prominent in hypertensive rats [23].

In a double-blind, placebo-controlled study, 106 Chinese-hypertensive subjects with diastolic blood pressure between 95 and 110 mmHg received either 250 mg of stevioside, isolated from Stevia rebaudiana, or placebo three times daily for one year. After three months, the systolic and diastolic blood pressure of the stevioside group decreased significantly (systolic: 166 to 152 mmHg; diastolic: 105 to 90 mmHg) , and the effect persisted during the whole year [24].

Olive leaf (Olea europea)

Olive leaf contains iridoid glycosides, which act as vasodilator [25]. In one clinical trial, daily supplementation with an aqueous extract of Olea europea, 400mg four times daily, for three months was found to decrease blood pressure in hypertensive patients [26].

Achillea Wilhelmsii

Achillea Wilhelmsii C. Koch (Asteraceae) is a wild herb widely disturbed in Iran. The herb contains alkaloids, which have been shown to lower blood pressure. In a double-blind, placebo-controlled trial, patients with mild hypertension were given either an Achillea Wilhelmsii extract (standardized to provide 1mg flavonoids), or a placebo, two times a day for 6 months. The Achillea-group showed a significant decrease in the diastolic blood pressure after 2 months, which continued till the end of 6 months, and a significant decrease in systolic blood pressure only at the end of the treatment period [27].

Fermented milk

In a recent randomized placebo-controlled study, 39 patients with mild hypertension received 150 mL/d or either L. helveticus LBK-16H fermented milk or a control product for 21 weeks. At the end of the trial there was a difference of 6.7 mmHg in systolic blood pressure and of 3.6 mmHg in diastolic blood pressure between the test product and control groups. The study concluded that daily consumption of L. helveticus LBK-16H fermented milk containing bioactive peptides lowers blood pressure in hypertensive subjects [28].

As with conventional medications, the use of dietary supplements sometimes controls blood pressure if taken consistently but does not lead to a cure for high blood pressure.

References

[1] Appel LJ et al. A clinical trial of the effects of dietary patterns on blood pressure. DASH Collaborative Research Group. New England Journal of Medicine 1997; 336:1117

[2] Stamler J et al. Relation of body mass and alcohol, nutrient, fiber, and caffeine intakes to blood pressure in the special intervention and usual care groups in the multiple Risk Factor Intervention Trial. Am J Clin Nutr 1997; 65 (suppl):338S

[3] Alderman MH. Non-pharmacologic approaches to the treatment of hypertension. Lancet 1994; 334:307

[4] Bucher HC et al. Effects of dietary calcium supplementation on blood pressure. A meta-analysis of randomized controlled trials. JAMA 1996; 275:1016

[5] Allender PS et al. Dietary calcium and blood pressure: a meta-analysis of randomized clinical trials. Ann Intern Med 1996; 124:825

[6] Altura B. magnesium in cardiovascular biology. Scientific American, Science and Medicine 1995; May/June:28

[7] Jee SH et al. The effects of magnesium supplementation on blood pressure: a meta-analysis of randomized clinical trials. Am J Hypertens 2002; 15:691

[8] Whelton PK et al. Effects of oral potassium on blood pressure: meta-analysis of randomized controlled clinical trials. JAMA 1997; 277:1624

[9] Siani A, Pagano E, et al. Blood pressure and metabolic changes during dietary L-arginine supplementation in humans. Am J Hypertens 2000; 13:547

[10] Digiesi V et al. Mechanism of action of coenzyme Q10 in essential hypertension. Curr Ther 1992; 51:668

[11] Morris MC et al. Does fish oil lower blood pressure? A meta-analysis of controlled trials. Circulation 1993; 88:523

[12] Mori TA et al. Docosahexaenoic acid but not eicosapentaenoic acid lowers ambulatory blood pressure and heart rate in humans. Hypertension 1999; 34:253

[13] Silagy C et al. A meta-analysis of the effect of garlic on blood pressure. J Hypertens 1994; 12:463

[14] Haji F, Haji T. The effect of sour tea (Hibiscus sabdariffa) on essential hypertension. J Ethnopharmacol 1999; 65:231

[15] Onyenekwe P.C., Ajani E.O. et al. Antihypertensive effect of Roselle (Hibiscus sabdariffa) calyx infusion in spontaneously hypertensive rats and a comparison of its toxicity with that in Wistar rats. Cell Biochem Funct 1999; 17:199

[16] Chen C-C et al. Hibiscus sabdariffa extract inhibits the development of atherosclerosis in cholesterol-fed rabbits. J Agric Food Chem 2003; 51:5472

[17] American Journal of Medicine 2003; 114:665

[18] Walker AF et al. Promising hypotensive effect of hawthorn extract: a randomized double-blind pilot study of mild, essential hypertension. Phytother Res 2002; 16:48

[19] Wysman DG et al. Effects of forskholin on cerebral blood flow: implications for a role of a denylate cyclase. Stroke 1986; 17:1299

[20] Wong S, et.al. Forskolin inhibits platelet-activating factor binding to platelet receptors independently of adenylyl cyclase activation. Eur J Pharmacol 1993; 245:55 [21] Dubey MP et al. Pharmacological studies on coleonol, a hypotensive diterpene from Colus forskohlii. J Ethnopharmacol 1981; 3:1

[22] Smith WM. Treatment of mild hypertension: results of a ten-year intervention trial. Circ Res 1977; 40:198

[23] Hsu YH et al. Antihypertensive effect of stevioside in different strains of hypertensive rats.Zhonghua Yi Xue Za Zhi (Taipei) 2002; 65:1

[24] Chan P et al. A double-blind placebo-controlled study of the effectiveness and tolerability of oral stevioside in human hypertension. Br J Clin Pharmacol 2000; 50:215

[25] Petkov V, Manolov O. Pharmacological analysis of the iridoid oleuropein. Arzneimittelforschung 1972; 22:1476

[26] Cherif S, Rahal N et al. A clinical trial of an olea extract in the treatment of essential arterial hypertension. J Pharm Belg 1996; 51:69

[27] Asgary S, Naderi GH et al. Antihypertensive and antihyperlipidemic effects of Achillea wilhelmsii. Drugs Exp Clin Res 2000; 26:89

[28] Seppo L et al. A fermented milk high in bioactive peptides has a blood pressure-lowering effects in hypertensive subjects. Am J Clinic Nutr 2003; 77:326

 

Products: