Statement from the National High Blood Pressure
Education Program
Coordinating Committee Revised October 14, 1999
Cardiovascular disease is the primary cause of death
in the United States. A major contributor to the development of cardiovascular
disease is blood pressure above the optimal level of less than 120/less than 80
mm Hg. This includes blood pressures in the hypertensive range of 140 to 159 mm
Hg systolic or 90 to 99 mm Hg diastolic.
Over the past several decades, there have been
impressive declines in the rates of coronary heart disease and stroke in the
United States. The declines were related, in part, to the increasing use of
antihypertensive therapy. However, the majority of Americans with hypertension
still do not have their condition under control, and nearly half of those with
hypertension are not being treated.
In addition, an even larger proportion of Americans
have blood pressures at the high end of the normal range (130 to 139 mm Hg
systolic or 85 to 89 mm Hg diastolic), which places them at an above-average
risk for developing cardiovascular disease. These persons can benefit from a
primary prevention approach that would keep them from developing hypertension.
One part of this approach is to lower dietary sodium intake.
There is a clear causal link between habitual sodium
intake and blood pressure. The evidence taken as a whole is sufficiently strong
to warrant a specific recommendation about reducing dietary salt intake. For
instance, experimental data with animals have consistently shown that diets
high in salt raise blood pressure in a linear dose-response relationship. The
findings include data from a study of chimpanzees, the animal species
genetically closest to humans. Cross-population studies also have confirmed the
salt-blood pressure relationship. Additionally, within-population studies,
including the large INTERSALT study, have shown that lowering sodium intake by
100 mmol (about 2,300 mg) a day--from 170 mmol (about 3,800 mg) to 70 mmol
(about 1,500 mg)--is associated with a 3 to 6 mm Hg reduction in systolic blood
pressure. A 3 mm Hg reduction in systolic blood pressure for the general U.S.
population would result in 11 percent fewer strokes, 7 percent fewer coronary
events, and 5 percent fewer deaths.
Data from the 1988-91 National Health and Nutrition
Examination Survey (NHANES III) give an estimated average dietary sodium intake
for U.S. adults ages 20 years and older of 3,400 mg per day. The estimated
average intake is similar for all race and ethnic groups. The estimated average
of 3,400 mg per day does not include discretionary sodium use, such as salt
added in cooking or at the table. It is estimated that adding in discretionary
sodium use would increase the average daily intake by about 15 percent. Thus,
the average American adult ingests nearly 4,000 mg of sodium daily. This level
is far above the current National Research Council recommendation that the
general U.S. population consume no more than 2,400 mg of sodium (or 6 grams of
salt) per day.
Studies over the past decade indicate that there has
been little change during that period in the average U.S. dietary sodium
intake. However, during that period, there have been important qualitative
changes in the average U.S. diet, particularly in the proportion of calories
derived from total fat and saturated fat. The lack of change in dietary sodium
intake may be partly due to the lack of a consistent health message about the
importance of reducing dietary sodium. This view is supported by data that show
a continuing decline in the percentage of Americans who think dietary sodium is
important.
Approximately 75 percent of dietary sodium is added to
food during its processing and manufacturing. Only 10 percent of dietary salt
comes from foods' natural content. Therefore, a high dietary salt intake is
associated with diets in which a large portion of the daily calories consists
of processed foods. Conversely, diets that have a higher proportion of fruits,
vegetables, and legumes are associated with lower blood pressures. They also
are consistent with current public health recommendations for diets, including
the 1990 Federal Government's Dietary Guidelines for Americans. By following
recommendations for lower sodium intake, consumers will encourage manufacturers
of processed foods to expand the types and availability of lower sodium
products. This should gradually reduce the sodium content of the U.S. food
supply. Until then, consumers must be careful to select lower sodium products,
especially among ready-to-eat cereals and certain other grain products.
Evidence of the efficacy and safety of a dietary
sodium intake of about 2,400 mg per day was reviewed and affirmed in 1989 by
the National Academy of Sciences and in 1993 by the National High Blood
Pressure Education Program Working Group on Primary Prevention. The evidence
was reaffirmed both in the Sixth Report of the Joint National Committee on
Prevention, Detection, Evaluation, and Treatment of High Blood Pressure
(JNC VI) and by a National Heart, Lung, and Blood Institute-sponsored workshop
on sodium and blood pressure, which was held in January 1999.
These reviews concurred that lowering Americans' daily
dietary sodium intake to 2,400 mg will reduce the U.S. population's mean blood
pressure. They also concurred that 2,400 mg is a safe level of daily sodium
intake and is not associated with adverse effects. Healthy adults living in a
temperate climate can maintain a normal sodium balance with as little as 115 mg
of dietary sodium per day. In consideration of the wide variation in Americans'
physical activity and climatic exposure, a safe minimum of 500 mg of sodium per
day has been recommended. Data from animal experiments, epidemiologic studies,
and randomized clinical trials have found no long-term adverse effects
associated with habitual sodium intake in the ranges cited (500 to 2,400 mg per
day). Findings from epidemiologic studies published in the past few years that
suggested there were adverse effects from such an intake had methodological
limitations. Such findings have not been independently confirmed.
We believe that gradually reducing the sodium content
of food--thus making available more lower sodium foods--is a prudent and safe
public health intervention. Such an action also will meet a growing consumer
demand for lower sodium products. Consumer education and product availability
must go hand in hand. If they do, the benefits reaped will be very large.
Therefore, be it resolved that the National High Blood
Pressure Education Program Coordinating Committee reconfirms its 1995
recommendations that the Dietary Guidelines Committee should emphasize
moderation in Americans' consumption of salt and sodium and that a daily intake
of no more than 2,400 mg of sodium should be a national goal.
Information regarding the National High Blood Pressure
Education Program can be found on the Web site
www.nhlbi.nih.gov. The member
organizations of the Coordinating Committee are
American Academy of Family Physicians American
Academy of Insurance Medicine American Academy of Neurology American
Academy of Ophthalmology American Academy of Physician Assistants
American Association of Occupational Health Nurses American College of
Cardiology American College of Chest Physicians American College of
Occupational and Environmental Medicine American College of Physicians
American College of Preventive Medicine American Dental Association
American Diabetes Association American Dietetic Association
American Heart Association American Hospital Association American
Medical Association American Nurses Association American Optometric
Association American Osteopathic Association American Pharmaceutical
Association American Podiatric Medical Association American Public
Health Association American Red Cross American Society of
Health-System Pharmacists American Society of Hypertension
Association of Black Cardiologists Citizens for Public Action on High
Blood Pressure and Cholesterol, Inc. Council on Geriatric Cardiology
International Society on Hypertension in Blacks National Black Nurses
Association, Inc. National High Blood Pressure Education Program
National Hypertension Association, Inc. National Kidney Foundation, Inc.
National Medical Association National Optometric Association
National Stroke Association NHLBI Ad Hoc Committee on Minority Populations
Society for Nutrition Education Agency for Health Care Policy and
Research Department of Veterans Affairs Health Care Financing
Administration Health Resources and Services Administration National
Center for Health Statistics National Institute of Diabetes and Digestive
and Kidney Diseases |