Category Archives: Hypertension

Alcohol, blood pressure, and hypertension

Alcohol intake and blood pressure

Many studies have shown a direct, dose-dependent relationship between alcohol intake and blood pressure, particularly for intake above two drinks per day.
This relationship is independent of:

  • age;
  • salt intake;
  • obesity;
  • finally, it persists regardless of beverage type.

Furthermore, heavy consumption of alcoholic beverages for long periods of time is one of the factors predisposing to hypertension: from 5 to 7% of hypertension cases is due to an excessive alcohol consumption.
A meta-analysis of 15 randomized controlled trials has shown that decreasing alcoholic beverage intake intake has therapeutic benefit to hypertensive and normotensive with similar systolic and diastolic blood pressure reductions (in hypertensive reduction occurs within weeks).

Alcohol intake and prevention of hypertension

Alcohol
Fig. 1 – Glass of Red Wine

Guidelines on the primary prevention of hypertension recommend that alcohol (ethanol) consumption in most men, in absence of other contra, should be less than 28 g/day, the limit in which it may reduce coronary heart disease risk.
The consumption limited to these quantities must be obtained by intake of drinks with low ethanol content, preferably at meals (drinking even lightly to moderately outside of meals increases the probability to have hypertension). This means no more than 680 ml or 24 oz of regular beer or 280 ml or 10 oz of wine (12% ethanol), especially in hypertension; for women and thinner subjects consumption should be halved1.
To avoid intake of drinks with high ethanol content even though the total ethanol content not exceeding 28 g/day.

Relationship between alcohol intake and blood pressure

Anyway, uncertainty remains regarding benefits or risks attributable to light-to-moderate alcoholic beverage intake on the risk of hypertension.
In a study published on April 2008, the authors examined the association between ethanol intake and the risk of developing hypertension in 28848 women from “The Women’s Health Study” and 13455 men from the “Physicians’ Health Study”, (the follow-up lasted respectively for 10.9 and 21.8 years). The study confirms that heavy ethanol intake (exceeding 2 drinks/day) increases hypertension risk in both men and women but, surprisingly, found that the association between light-to-moderate alcohol intake (up to 2 drinks/day) and the risk of developing hypertension is different in women and men. Women have a potential reduced risk of hypertension from a light-to-moderate ethanol consumption with a J-shaped association2; men have no benefits of light-to-moderate ethanol consumption but an increased risk of hypertension.
However, guidelines for the primary prevention of hypertension limit alcohol consumption to less 2 drinks/day in men and less 1 drink/day in thinner subjects and women.

1. A standard drink contains approximately 14 g of ethanol i.e. a 340 ml or 12 oz of regular beer, 140 ml or 5 oz wine (12% alcohol), or 42 ml or 1,5 oz of distilled spirits (inadvisable).

2. Many studies have shown a J-shaped relationship between ethanol intake and blood pressure. Light drinker (no more than 28 g of ethanol/day) have lower blood pressure than teetotalers; instead, who consumes more than 28 g ethanol/day have higher blood pressure than non drinker. So alcohol is a vasodilator at low doses but a vasoconstrictor at higher doses.

References

Pickering T.G. New Guidelines on Diet and Blood Pressure. Hypertension 2006;47:135-6 [Full text]

Sesso H.D., Cook N.R., Buring J.E., Manson J.E. and Gaziano J.M. Alcohol consumption and the risk of hypertension in women and men. Hypertension 2008;51:1080-87 [Abstract]

Writing Group of the PREMIER Collaborative Research Group. Effects of Comprehensive Lifestyle Modification on Blood Pressure Control: Main Results of the PREMIER Clinical Trial. JAMA 2003;289:2083-2093 [Abstract]

World Health Organization, International Society of Hypertension Writing Group. 2003 World Health Organization (WHO)/International Society of Hypertension (ISH) statement on management of hypertension. Guidelines and recommendations. J Hyperten 2003;21:1983-92. [Abstract]


Overweight, physical activity, blood pressure, and hypertension

Overweight, obesity and blood pressure

Body weight is a determinant of blood pressure at all age; in fact:

  • it has been estimated that the risk of developing elevated blood pressure is two to six time higher in overweight than in normal-weight individuals;
  • there is a linear correlation between blood pressure and body weight or body mass index (BMI) (a BMI greater than 27, i.e. overweight or obesity, is correlated with increased blood pressure): even when dietary sodium intake is held constant, the correlation between change in weight and change in blood pressure is linear;
  • 60% of hypertensives are more than 20% overweight;
  • centripetal distribution of body fat (waist circumference greater than 34 inches in women and 39 inches in man), also associated with insulin resistance, is more important determinant of blood pressure elevation than that peripherally located in both man and women;
  • it has been shown that weight loss, both in hypertensive and normotensive individual, can reduce blood pressure and reductions occur before, and without, attainment of a desirable body weight.

In view of the difficulties of sustaining weight loss, efforts to prevent weight gain among those who have normal body weight are critically important.

How to calculate BMI

overweight
Fig. 1 – BMI Chart

BMI is total body weight, expressed in kilograms [kg] or pounds [lb], divided by the height squared, expressed in meters or inches (in.).
It can be calculated using the following equations:

BMI = weight [kg]/height2 [m] or
BMI = (weight [lb.]/heigth2 [in.]) x 705

BMI is a good indication of body fat because most of the weight differential among adults is due to body fat; its major flaw is that some muscular individuals may be classified as obese even if they are not.
A healthy BMI is between 18 to 24,9.
Overweight is considered to be between 25 to 29,9.
Obesity is categorized by BMI according to three grades:

  • 30 to 34,9 I grade obesity;
  • 35 to 40 II grade obesity:
  • 40 and above III grade obesity.

Physical activity, and blood pressure

Maintaining a high level of physical activity is a critical factor in sustaining weight loss.
In addition to the effect on body weight, activity and exercise in itself reduce the rise in blood pressure.
Physical activity produces a fall in systolic blood pressure and diastolic blood pressure; so, increasing physical activity of low to moderate intensity to 30 to 45 minutes 3-4 days/week up to 1 hour nearly every day, as recommended by World Health Organization, is important for the primary prevention of hypertension.
Less active persons are 30% to 50% more likely to develop hypertension than active ones.
Remember: a rolling stone gathers no moss!

References

Mahan LK, Escott-Stump S.: “Krause’s foods, nutrition, and diet therapy” 10th ed. 2000

Shils M.E., Olson J.A., Shike M., Ross A.C. “Modern nutrition in health and disease” 9th ed., by Lippincott, Williams & Wilkins, 1999

Writing Group of the PREMIER Collaborative Research Group. Effects of Comprehensive Lifestyle Modification on Blood Pressure Control: Main Results of the PREMIER Clinical Trial. JAMA 2003;289:2083-2093 [Abstract]

World Health Organization, International Society of Hypertension Writing Group. 2003 World Health Organization (WHO)/International Society of Hypertension (ISH) statement on management of hypertension. Guidelines and recommendations. J Hyperten 2003;21:1983-92 [Abstract]

Potassium intake, blood pressure and hypertension

Potassium intake and blood pressure

High dietary potassium (K+) intakes and blood pressure are inversely related: animal studies, observational epidemiological studies, clinical trials, and meta-analyses of these trials support this.
Furthermore, the prevalence of hypertension tends to be lower in populations with high K+ intakes than in those with low intakes.
Finally, an increase in potassium intake (2.5-3.9 g/d) reduces blood pressure in normotensive and hypertensive, and to a greater extent in blacks than in whites.

Dash Diet and potassium intake

Controlled feeding studies (“The Dietary Approaches to Stop Hypertension (DASH) Study” and “OmniHeart Trial”) have highlighted the role of a good potassium intake, along with other minerals and fiber, in blood pressure reduction.
These studies have shown that a dietary pattern rich in fruits, vegetables, and low-fat dairy products, with whole grains, poultry, fish and nuts but poor in fats, red meat, sweets, and sugar-containing beverages reduces blood pressure.
These dietary patterns are rich in foods high in K+, as well as magnesium, calcium and fiber, but poor in total fat, saturated fat and cholesterol.
The best result on lowering blood pressure are with black participants than white participants.

Potassium, sodium and blood pressure

The effects of potassium on blood pressure depend on the concurrent intake of sodium and vice versa:

  • an increased intake of K+ has:

a greater blood pressure-lowering effect when sodium intake is high;

a lesser blood pressure-lowering effect when sodium intake is low;

  • on the other hand, the blood pressure reduction from a lowered sodium intake is greatest when potassium intake is low.

An high K+ intake also increases urinary excretion of sodium, the so-called natriuretic effect.
In the generally healthy population with normal kidney function the recommended potassium intake level is 3.1 g/day. But, in the presence of impaired urinary potassium excretion, a K+ intake less than 3.1 g/day (120 mmol/d) is appropriate, because of adverse cardiac effects (arrhythmias) from hyperkalemia, that is, blood potassium level higher than normal.

Mediterranean Diet and potassium intake

Potassium
Fig. 1 – Fruit, Vegetables, and Blood Pressure

As already pointed out, the best strategy to increase K+ intake is to consume legumes, and fruits and vegetables in season, i.e. foods high in  potassium, that is also accompanied by a variety of other nutrients. No supplements are needed.
Therefore, it is sufficient to follow a  Mediterranean dietary pattern, for:

  • meet the daily requirements of the mineral;
  • consume K+ intake in adequate amounts to ensure its blood pressure-lowering effect.

Potassium content in some foods

High content: >250 mg/100 g of product

  • Dried legumes (chickpeas, beans, lentils, peas and soybeans) and fresh beans;
  • garlic, chard, cauliflower, cabbage, Brussels sprouts, broccoli, artichokes, cardoons, fennel, mushrooms, potatoes, tomatoes, spinach, zucchini;
  • avocados, apricots, bananas, fresh and dried chestnuts, watermelon, kiwi, melon, hazelnuts;
  • sweet dried fruits (apricots, dates, figs, prunes, raisins etc..) and oily dried fruits (peanuts, almonds, walnuts, pine nuts, pistachios, etc.);
  • oat flour, whole wheat flour and spelt;
  • ketchup;
  • roasted coffee;
  • milk powder (also rich sodium);
  • yeast;
  • cocoa powder.

Medium content: 150-250 mg/100 g of product

  • asparagus, beets, carrots, chicory, green beans, fresh broad beans, endive, lettuce, peppers, fresh peas, tomatoes, leeks, radishes, celery, tomato and carrot juice, pumpkin;
  • pineapple, oranges, raspberries, blueberries, loquats, pears, peaches, grapefruit, grapes;
  • meat and fish products, both fresh and preserved (the latter, however, should be avoided because of their high sodium content).

Note: cooking methods tend to reduce the K+ content of the food.
To reduce potassium loss, avoid boiling in plenty of water, for more than an hour, vegetables cut into small pieces (this increases the “exchange area” with water).

References

Appel L.J., Brands M.W., Daniels S.R., Karanja N., Elmer P.J. and Sacks F.M. Dietary Approaches to Prevent and Treat Hypertension: A Scientific Statement From the American Heart Association. Hypertension 2006;47:296-08 [Abstract]

Cappuccio F.P. and MacGregor G.A. Does potassium supplementation lower blood pressure? A metaanalysis of published trials. J Hyperten 1991;9:465-73 [Abstract]

Geleijnse J.M., Witteman J.C., den Breeijen J.H., Hofman A., de Jong P., Pols H.A. and Grobbee D.E. Dietary electrolyte intake and blood pressure in older subjects: the Rotterdam Study. J Hyperten 1996;14:73741 [Abstract]

Mahan LK, Escott-Stump S.: “Krause’s foods, nutrition, and diet therapy” 10th ed. 2000

Matlou S.M., Isles C.G. and Higgs A. Potassium supplementation in Blacks with mild to moderate essential hypertension. J Hyperten 1986;4:61-4  [Abstract]

Nutrient Data Home (USDA)

Pickering T.G. New Guidelines on Diet and Blood Pressure. Hypertension 2006;47:135-6 [Full text]

Rose G. Desirability of changing potassium intake in the community. In: Whelton P.K., Whelton A.K. and Walker W.G. eds. Potassium in cardiovascular and renal disease. Marcel Dekker, New York 1986;411-16

Shils M.E., Olson J.A., Shike M., Ross A.C. “Modern nutrition in health and disease” 9th ed., by Lippincott, Williams & Wilkins, 1999

Tabelle di composizione degli alimenti; aggiornamento 2000. I.N.R.A.N.

Writing Group of the PREMIER Collaborative Research Group. Effects of Comprehensive Lifestyle Modification on Blood Pressure Control: Main Results of the PREMIER Clinical Trial. JAMA 2003;289:2083-2093 [Abstract]

World Health Organization, International Society of Hypertension Writing Group. 2003 World Health Organization (WHO)/International Society of Hypertension (ISH) statement on management of hypertension. Guidelines and recommendations. J Hyperten 2003;21:1983-92. [Abstract]

Sodium: blood pressure, requirements, intake, sources

Sodium and blood pressure

A high sodium (Na+) intake (the main source is salt or sodium chloride, NaCl) contributes to blood pressure raise, and hypertension development.
Many epidemiologic studies, animal studies, migration studies, clinical trials, and meta-analyses of trials support this, with the final evidence from rigorously controlled, dose-response trials. Furthermore, in primitive society Na+intake is very low and people experience very low hypertension, and the blood pressure increase with age does not occur.
Probably, sodium intake effect sizes are to be underestimated!

Recommended daily intake of sodium

Sodium
Fig. 1 – Salt Pans of Trapani

Sodium’s physiologic requires are very low; in fact, the minimum recommended Na+ intake for maintain life is 250 mg/day (Note: iodized salt is an important source of dietary iodine in the United States and worldwide).
An Americans consumes the mineral in great excess of physiologic requires: despite the guidelines from the Departments of Agriculture and Health and Human Services, during the period from 2005 through 2006 the average salt intake in USA is of 10.4 g/day for the average man and 7.3 for the average woman, amount in excess regarding preceding years.
A study published on February 2010 on “The New England Journal of Medicine” have shown that “A population-wide reduction in dietary salt of 3 g per day (1200 mg of Na+ per day) is projected to reduce the annual number of new cases of coronary heart disease (CHD) by 60,000 to 120,000, stroke by 32,000 to 66,000, and myocardial infarction by 54,000 to 99,000 and to reduce the annual number of deaths from any cause by 44,000 to 92,000″ (Bibbins-Domingo et all., see References). These benefits are similar in magnitude to those from:

  • a 50% reduction in tobacco use;
  • a 5% reduction in body mass index among obese adults;
  • a reduction in cholesterol levels.

These benefits regard all adult group age, black and nonblack, male and female. The benefits for black are greater than nonblack, in both sex and all age group. It’s estimated an annual savings of $10 billion to 24 $ billion in health care costs.
Clinical trials have also documented that a reduced Na+ intake can lower blood pressure in the setting of antihypertensive medication, and can facilitate hypertension control.
But, in USA dietary salt intake is on the rise!
So, it is recommended, to prevent hypertension development, a reduction in its intake and, in view of the available food supply and the currently daily Na+ intake, a reasonable recommendation is an upper limit of 2.3 g/day (5.8 g/day of salt).
How achieves this level? It can be achieved:

  • cooking with as little salt as possible;
  • refraining from adding salt at the table;
  • avoiding highly salted, processed foods.

Dietary sources of sodium

Sodium
Fig. 2 – Salt Shaker

They include:

  • salt used at the table: up to 20% of the daily salt intake;
  • salt or sodium compounds added during preparation or processing foods: between 35 to 80% of the daily sodium intake comes from processed foods.
    Which foods are?
    Processed, smoked or cured meat and fish e.g. sliced salami, sausage, salt pork, tuna fish in oil etc.; meat extracts and sauce, salted snack, soy sauce, barbecue sauce, commercial salad dressing; prepackage frozen foods; canned soup, canned legumes; cheese etc.
    There are also many sodium-containing additives as disodium phosphate (e.g. in cereals, ice cream, cheese), monosodium glutamate (i.e. meat, soup, condiments), sodium alginate (e.g. in ice creams), sodium benzoate (e.g. in fruit juice), sodium hydroxide (e.g. in pretzels, cocoa product), sodium propionate (e.g. in bread), sodium sulfite (e.g. in dried fruit), sodium pectinate (e.g. syrups, ice creams, jam), sodium caseinate (e.g. ice creams and other frozen products) and sodium bicarbonate (e.g. baking powder, tomato soup, confections).
    So pay attention to ingredients!
  • Inherent sodium of foods. Generally low in fresh foods.

The blood pressure response to lower dietary Na+ intake is heterogeneous with individuals having greater or lesser degrees of blood pressure reduction. Usually the effect of reduction tend to be greater in blacks, middle-aged and older persons, and individuals with hypertension, diabetes or chronic kidney disease.
Furthermore genetic and dietary factors influence the response to sodium reduction.

How diet can modify response of blood pressure to sodium?

Some components of the diet may modify response of blood pressure to sodium.

  • A high dietary intake of calcium and potassium rich foods, such as fruit, vegetable, legumes (e.g. Mediterranean diet), and low-fat dairy products (e.g. DASH diet), may prevent or attenuate the rise in blood pressure for a given increase in sodium intake.
  • Some evidences, seen primarily in animal model, suggest that high dietary intake of sucrose may potentiate salt sensitivity of blood pressure.

Note: high Na+ intake can contribute to osteoporosis: they result in an increase in renal calcium excretion, particularly if daily calcium intakes are low.

References

Appel L.J., Brands M.W., Daniels S.R., Karanja N., Elmer P.J. and Sacks F.M. Dietary Approaches to Prevent and Treat Hypertension: A Scientific Statement From the American Heart Association. Hypertension 2006;47:296-08 [Abstract]

Bibbins-Domingo K., Chertow G.M., Coxson P.G., Moran A., Lightwood J.M., Pletcher M.J., and Goldman L. Projected effect of dietary salt reductions on future cardiovascular disease. N Engl J Med 2010;362:590-9 [Abstract]

Cappuccio FP. Overview and evaluation of national policies, dietary recommendtions and programmes around the world aiming at reducing salt intake in the population. World Health Organization. Reducing salt intake in populations: report of a WHO forum and technical meeting. WHO Geneva 2007;1-60 [PDF]

Chen J, Gu D., Jaquish C.E., Chen C., Rao D.C., Liu D., Hixson J.E., Lee Hamm L., Gu C.C., Whelton P.K. and He J. for the GenSalt Collaborative Research Group. Association Between Blood Pressure Responses to the Cold Pressor Test and Dietary Sodium Intervention in a Chinese Population. Arch Intern Med. 2008;168:1740-46 [Abstract]

Denton D., Weisinger R., Mundy N.I. et al. The effect of increased salt intake on blood pressure of chimpanzees. Nature Med 1995;10:1009-16 [Abstract]

Ford E.S., Ajani U.A., Croft J.B. et al. Explaining the decrease in U.S. deaths from coronary disease, 1980-2000. N Engl J Med 2007;356:2388-98 [Abstract]

Geleijnse J.M., Witteman J.C., den Breeijen J.H., Hofman A., de Jong P., Pols H.A. and Grobbee D.E. Dietary electrolyte intake and blood pressure in older subjects: the Rotterdam Study. J Hyperten 1996;14:73741 [Abstract]

Harlan W.R. and Harlan L.C. Blood pressure and calcium and magnesium intake. In: Laragh J.H., Brenner B.M., eds. Hypertension: pathophysiology, diagnosis and management. 2end ed. New York: Raven Press 1995;1143-54

Holmes E., Loo R.L., Stamler J., Bictash M., Yap I.K.S., Chan Q., Ebbels T., De Iorio M., Brown I.J., Veselkov K.A., Daviglus M.L., Kesteloot H., Ueshima H., Zhao L., Nicholson J.K. and Elliott P. Human metabolic phenotype diversity and its association with diet and blood pressure. Nature 2008;453:396-400 [First paragraph]

Mahan LK, Escott-Stump S.: “Krause’s foods, nutrition, and diet therapy” 10th ed. 2000

Pickering T.G. New Guidelines on Diet and Blood Pressure. Hypertension 2006;47:135-6 [Full text]

Shils M.E., Olson J.A., Shike M., Ross A.C. “Modern nutrition in health and disease” 9th ed., by Lippincott, Williams & Wilkins, 1999

Simpson F.O. Blood pressure and sodium intake. In: Laragh J.H., Brenner B.M. eds. Hypertension: pathophysiology, diagnosis and management. 2end ed. New York: Raven Press 1995;273-81

Strazzullo P., D’Elia L., Kandala N. and Cappuccio F.P. Salt intake, stroke, and cardiovascular disease: meta-analysis of prospective studies. BMJ 2009;339:b4567 [Abstract]

Tzoulaki I., Brown I.J., Chan Q., Van Horn L., Ueshima H., Zhao L., Stamler J., Elliott P., for the International Collaborative Research Group on Macro-/Micronutrients and Blood Pressure. Relation of iron and red meat intake to blood pressure: cross sectional epidemiological study. BMJ 2008;337:a258 [Abstract]

Weinberger M.H. The effects of sodium on blood pressure in humans. In: Laragh JH, Brenner BM, eds. Hypertension: pathophysiology, diagnosis and management. 2end ed. New York: Raven Press 1995;2703-14

Writing Group of the PREMIER Collaborative Research Group. Effects of Comprehensive Lifestyle Modification on Blood Pressure Control: Main Results of the PREMIER Clinical Trial. JAMA 2003;289:2083-2093 [Abstract]

World Health Organization, International Society of Hypertension Writing Group. 2003 World Health Organization (WHO)/International Society of Hypertension (ISH) statement on management of hypertension. Guidelines and recommendations. J Hyperten 2003;21:1983-92. [Abstract]