High Blood Pressure - the nutrition connection

By: 

ION Archives

Issue: 
Summer
Year of publication: 
2002

Hypertension is the medical term for high blood pressure, a condition with many causes. Geeta Jaisinghani, Dip.ION examines its link with dietary and lifestyle habits and provides research to show that hypertension, like most other maladies, is a disease of the modern day world

Blood pressure levels are generally high in the UK. As a nation we eat, drink and smoke too much and don’t take enough exercise – all of which are contributing factors to increased blood pressure.

High blood pressure puts considerable strain on the heart and blood vessels. As a result, the blood vessels become thicker and more rigid. This accelerates the process of atherosclerosis, which further aggravates blood pressure. Besides heart disease, high blood pressure increases the risk of a number of other conditions including kidney failure, blindness and stroke – the latter along with cardiovascular disease being some of the biggest killers of people in Britain.

Approximately 80% of people with high blood pressure are borderline-tomoderate in severity. In such cases, medical authorities, (including the British Heart Foundation and the Joint National Committee on Detection Evaluation and Treatment of High Blood Pressure, Maryland, USA), recommend non-drug therapies such as changes in diet and lifestyle, including weight loss, and an increase in physical activity.(1) Dr Mark Porter, columnist and television GP, states that losing excess weight, eating healthily, increasing exercise levels, stopping smoking, and cutting back on alcohol and salt, may be all that’s required to reduce high blood pressure in mild cases. Drugs should only be used as a supplement to key lifestyle changes, not as a substitute.(2)

Blood pressure denotes the resistance produced each time the heart beats and sends blood coursing through the arteries. The peak reading of the pressure exerted by this contraction is known as the systolic pressure. Between beats the heart relaxes and blood pressure drops. The lowest reading is referred to as the diastolic pressure. A fit person in their 20s should have a blood pressure of around 120/80 mmHg. Traditionally, readings above 160/90 have been regarded as high but recent research suggests that 140/85 is a better cut-off point – anything above this, agree the experts, needs monitoring. For each 5 mmHg reduction in diastolic pressure the risk of coronary heart disease (CHD) is reduced by about 16%.(3)

SYMPTOMS

There are no consistent signs and symptoms of hypertension. Contrary to common belief, headaches, nosebleeds and facial flushing are not reliable indicators. Most people with high blood pressure are not aware that they have a problem unless it’s picked up by a doctor or nurse. That’s why routine blood pressure checks are essential, particularly in people over the age of 45 when hypertension becomes significantly more common.

Because blood pressure can vary from day to day, the diagnosis of hypertension is generally based on an average of at least three readings. Each individual needs to be independently assessed and the treatment goals adjusted accordingly.

RISK FACTORS

High blood pressure is closely related to dietary and lifestyle factors. Some of the dietary factors that may affect blood pressure include obesity, high sodium to potassium ratio, low fibre intake, excess sugar or alcohol, caffeine consumption, high saturated fat and low essential fatty acid intake; and a diet low in calcium, magnesium and vitamin C. Lifestyle factors that are associated with high blood pressure include lack of exercise, stress and smoking. Kidney problems, hormone imbalances, and medication such as steroids and the contraceptive pill have also been implicated.

CONVENTIONAL TREATMENT

There are four groups of medicinal drugs that are commonly prescribed for high blood pressure which may be used in combination, or on their own, depending on an individual’s state of health. These include angiotensin-converting enzyme (ACE) inhibitors, beta-blockers, calcium channel blockers, and diuretics. ACE inhibitors work by preventing the production of a chemical in the blood called angiotensin II, which has a powerful, constricting effect on the blood vessels. When angiotensin levels are lowered, the peripheral blood vessels relax and blood pressure falls. Beta-blockers slow the heart rate; calcium channel blockers act on blood vessels causing vasodilation; and diuretics are water tablets which increase urine production and therefore reduce water and blood volume in the body. Side effects of conventional medication may include lethargy, digestive disorders, asthma, skin rashes, facial flushing, headaches and heart palpitations.

LIFESTYLE AND DIETARY CHANGES IN HIGH BLOOD PRESSURE

Weight loss

A high percentage of people with elevated blood pressure are obese. The most effective method to possibly lower blood pressure in hypertensive individuals is to maintain normal weight or, if obese, to lose weight.

Most randomised controlled studies have shown that even a modest weight loss of 3-9% is associated with a significant reduction in systolic and diastolic blood pressure of roughly 3 mmHg in overweight people.(4)

The most common causes of obesity are excessive sugar and saturated fat intake, low blood sugar (hypoglycemia), crash diets, a faulty fat metabolism, heredity factors, glandular malfunctions, diabetes and a lack of exercise. Obesity has also been linked to food sensitivities and allergies, which may lead to water retention.

Experience shows that the use of liquid formulas or “crash” diets to lose weight is ineffective over the long term. The process of losing large amounts of weight quickly leads to a slowing down of the rate at which calories are burned (by as much as 20%) and a gain in weight once a more normal diet is resumed.

The most effective way to lose weight is to focus on all the causative factors such as eating habits, an imbalanced blood sugar level, malnutrition, allergies/intolerances, metabolism, and exercise. Weight loss and long-term weight stabilisation should be attacked from all angles, and careful guidance from a nutritional therapist who can look at these factors will prove invaluable. A simple, easy-to-follow, weight reduction programme, resulting in a loss of one to two pounds a week is the most effective way to lose weight.

Sodium restriction

There is a clear link between sodium intake and blood pressure. Primitive societies exposed to very little salt suffer from little or no hypertension. Most people ingest far more salt (sodium) than necessary. The average salt intake in the UK is approximately 9g/day, compared to 6g/day, which is recommended by the government.

The ideal way of obtaining sodium in the diet is via fresh, natural produce such as vegetables, legumes and wholegrains. Salt is added to processed convenience foods, bacon, sausages and other meat products, butter and margarine, canned vegetables, cheese, bread, breakfast cereals and everyday snacks. Despite its presence in so many foods, about one-third of the salt in the British diet is added during cooking or at the table. Another third comes from cereals and breads, one-sixth from meat and meat products, and the remaining sixth from other foods.

A randomised controlled trial in the USA indicated that the reduction of sodium intake along with the DASH (Dietary Approaches to Stop Hypertension) diet which is rich in vegetables, fruit, and low-fat dairy products, lowered blood pressure substantially in hypertensive individuals, with greater effect in combination rather than tackling the problem with one approach.(5) The long-term health benefits of such a diet will depend on the ability of people to make permanent dietary changes and the increased availability of lower-sodium foods.

Smoking

Smoking cigarettes stimulates the production of the stress hormones adrenaline and noradrenaline, both of which increase the heart rate and cause a temporary rise in blood pressure. Smoking increases the stickiness of platelets and the likelihood of clot formation. It also damages the lining of the blood vessels, making them more prone to atherosclerosis.

Dealing with stress

Stress may cause high blood pressure, particularly when it is experienced in excess or for prolonged periods of time. There is strong evidence to show that reducing stress, or coping better with it, can substantially reduce blood pressure. Breathing exercises, physical as well as mental relaxation, and quality sleep are important factors in stress management.

Increasing physical activity

Several recent studies have shown that cardiovascular risk can be reduced by a programme involving moderate exercise.(6) This includes walking for 30 to 40 minutes at a rate of two to three miles an hour, three to four times a week. Exercise is helpful in burning calories, thereby helping to reduce weight. It can also help increase vasodilator hormones that lower vascular resistance and may therefore help to lower blood pressure.

DIETARY APPROACHES

A diet rich in vegetables, fruit and low-fat dairy products (with reduced saturated and total fat) has been shown to reduce blood pressure in individuals with mild to moderate hypertension. This type of diet may possibly prevent the development of hypertension in some people.(7)

BLOOD PRESSURE LOWERING DIET

Include:

Celery for its 3-n-butylphthalide content which causes the smooth muscle surrounding the blood vessels to relax, therefore decreasing blood pressure. In studies, four celery stalks a day, reduced blood pressure by 10%.(8)
Garlic (one to two cloves a day) for its sulphur-containing compounds. Garlic is known to reduce platelet stickiness, reduce cholesterol and lower blood pressure.(9)
Nuts and seeds (one tablespoon a day of pumpkin, sunflower, sesame and linseeds), and cold water fish such as salmon, mackerel, tuna at least two to three times a week for their essential fatty acids.
Legumes and whole grains such as millet, buckwheat, quinoa, oats, brown rice, beans and lentils for their fibre content and good source of vegetarian protein.
Fruit and vegetables (minimum five to six servings a day) such as apples, asparagus, bananas, broccoli, cabbage, cantaloupe, grapefruit, green leafy vegetables, melon, peas, prunes, raisins, squash and sweet potatoes to provide antioxidants, potassium and other valuable nutrients.
Soya foods such as tofu, soya milk and soya yogurt, which provide an alternative to dairy products.
Drink at least two litres of filtered or mineral water a day.

Avoid/reduce:

Salt and all foods that contain added sodium.
Alcohol, tea and coffee.
Refined foods and sugar.
Wheat and dairy produce as they may lead to excess weight gain.
Animal fats and hydrogenated fats.

NUTRITIONAL SUPPLEMENTS THAT MAY BE BENEFICIAL

Coenzyme Q10

Coenzyme Q10 (CoQ10) is frequently deficient in hypertensive individuals. Both uncontrolled (10,11,12) and controlled trials have reported that CoQ10 significantly lowers blood pressure in people with hypertension.(13,14) All trials used at least 50mg of CoQ10 taken twice a day, and most trials lasted for at least ten weeks.

Suggested supplementary intake: 50mg twice a day.

Vitamin C

This vitamin has been found to have a blood pressure lowering effect in those with a mild elevation of blood pressure.(15) Studies have shown a correlation between higher intake of vitamin C and lower blood pressure.(16)

Suggested supplementary intake: 1000mg a day.

Magnesium

Some studies show that magnesium supplementation can lower blood pressure, particularly in people taking potassium-depleting diuretics.(17,18) As so-called “potassium depleting” diuretics also deplete magnesium, the drop in blood pressure resulting from magnesium supplementation in people taking these drugs may result from overcoming a mild magnesium deficiency.

Suggested supplementary intake: 200-300mg a day.

Potassium

A diet low in potassium and high in sodium increases the risk of high blood pressure. Potassium helps in the maintenance of water balance and distribution, acid-base balance of heart, and kidney function. Many studies have shown that increasing dietary potassium can lower blood pressure. However, high potassium intake in the form of a supplement, can produce stomach irritation. The best way to get extra potassium is to eat several pieces of fruit a day.

Fish oils

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the Omega-3 fatty acids found in fish oil, lower blood pressure, according to a meta-analysis of 31 trials.(19) Studies using over 3 grams of Omega-3 (generally requiring at least 10 grams of fish oil, or ten 1,000mg capsules a day) reported a significant reduction in blood pressure. However, high doses of fish oil should be avoided by those taking warfarin or aspirin, drugs which help to thin the blood, as fish oils have a similar effect.

Suggested supplementary intake: 1000mg(EPA) two to three times a day.

Garlic

Garlic lowers blood pressure, according to a meta-analysis that included ten double-blind studies.(20) All of these trials administered garlic for at least four weeks.

Suggested supplementary intake: 600-900mg of garlic extract a day.

Note: It is advisable to consult a nutritional therapist before embarking on a programme to help reduce high blood pressure.

 

REFERENCES

Appel LJ. Nonpharmacologic Therapies that Reduce Blood Pressure: A Fresh Perspective. Clin Cardiol 1999 Jul; 22 (7 Suppl):III1-5.
Porter, Mark. On the Case, High Blood Pressure. Health Talk Magazine, Norwich Union Healthcare Ltd, 1999, Vol page 14-15.
British Heart Foundation/Coronary Heart Disease Statistics/British Heart Foundation Statistics Database 1998 Edition, 14 Fitzhardinge Street London W1H 4DH, July 1999.
Hermansen K, Diet, Blood Pressure and Hypertension. Br J Nutr 2000; 83: S113-9.
Sacks FM, Svetkey LP, Vollmer WM, et al. Effects on Blood Pressure of Reduced Dietary Sodium and the Dietary Approaches to Stop Hypertension (DASH) Diet. N Engl J Med. 2001;344(1):53-5.
Cl´eroux J, Feldman RD, Petrella RJ. Lifestyle Modifications to Prevent and Control Hypertension. Recommendations on Physical Exercise Training. Canadian Hypertension Society, Canadian Coalition for High Blood Pressure Prevention and Control, Laboratory Centre for Disease Control at Health Canada, Heart and Stroke Foundation of Canada. CMAJ 1999; 160(9 Suppl): S21-8.
Svetkey LP, Simons-Morton D, Vollmer WM, et al. Effects of Dietary Patterns on Blood Pressure, Subgroup Analysis of the Dietary Approaches to Stop Hypertension (DASH) Randomized Clinical Trial. Arch Intern Med 1999;159 (3): 285-93.
Fox, Barry. Foods to Heal p.128, St. Martin's Paperbacks, 1996.
Auer W, Eiber A, Hertkorn E, et al. Hypertension and Hyperlipidaemia: Garlic Helps in Mild Cases. Br J Clin Pract Suppl. 1990;69:3-6
Folkers K, Drzewoski J, Richardson PC, et al. Bioenergetics in Clinical medicine. XVI. Reduction of Hypertension in Patients by Therapy with Coenzyme Q10. Res Commun Chem Pathol Pharmacol 1981;31:129–40.
Langsjoen P, Langsjoen P, Willis R, Folkers K. Treatment of Essential Hypertension with Coenzyme Q10. Mol Aspects Med 1994;15(Suppl):S265–72.
Digiesi V, Cantini F, Oradei A, et al. Coenzyme Q10 in Essential Hypertension. Molec Aspects Med 1994; 15 (Suppl): S257–63.
Digiesi V, Cantini F, Brodbeck B. Effect of Coenzyme Q10 on Essential Arterial Hypertension. Curr Ther Res 1990; 47:841-5.
Singh RB, Niaz MA, Rastogi SS, et al. Effect of Hydrosoluble Coenzyme Q10 on Blood Pressures and Insulin Resistance in Hypertensive Patients with Coronary Artery Disease. J Hum Hypertens 1999;13:203–8.
Bates CJ, Walmsley CM, Prentice A et al. Does Vitamin C Reduce Blood Pressure? Results of a Large Study of People Aged 65 or Older. Journal of Hypertension 1998;16:925-932.
Duffy SJ, Gokce N, Holbrook M, et al. Treatment of Hypertension with Ascorbic Acid. Lancet 1999;354(9195):2048-9.
Motoyama T, Sano H, Fukuzaki H, et al. Oral Magnesium Supplementation in Patients with Essential Hypertension. Hypertension 1989;13:227–32.
Dyckner T, Wester PO. Effect of Magnesium on Blood Pressure. BMJ 1983;286:1847–9.
Morris MC, Sacks F, Rosner B. Does Fish Oil Lower Blood Pressure? A Meta-Analysis of Controlled Trials. Circulation1993;88:523–33.
Silagy C, Neil AW. A Meta-Analysis of the Effect of Garlic on Blood Pressure. J Hypertension 1994;12:463–8.

BIBILIOGRAPHY

Fox B, Cameron A. Food Science, Nutrition and Health, Arnold, 1995.
Patel C. Fighting Heart Disease, DK Publishers 1987.
Murray M, Pizzorno J. Encyclopedia of Natural Medicine, Prime Health, 1998.
Passwater A. Richard, Cranton M Elmer. Trace elements, Hair analysis and Nutrition, Keats Publishing Inc., 1983.

Geeta Jaisinghani is a Dip.ION nutritionist practicing at the Woodbridge Complementary Health Centre in Ipswich and local health club.

 

 

 

 

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