FIT4 HEALTH PAGE

This page is a follow up to our FIT4 study in health and nutrition. Periodically, we will post items of interest that relate to health, nutrition, and wellness. Items from medical journals, latest research, and news of interest to those who wish to keep fit and healthy are presented for your benefit. Check back often for updates and new postings.

 

An analysis of the studies relating salt intake and blood pressure

By: Thomas Pickering, MD, DPhil, FRCP, Director of Integrative and Behavioral Cardiology Program of the Cardiovascular Institute at Mount Sinai School of Medicine, New York.

Dated: 9/5/96

For many years medical experts have been divided as to the effectiveness of restricting salt for lowering blood pressure. A new analysis has examined all the  published studies that have systematically tried to answer this question. In all cases subjects in the studies had their blood pressure measured before and after they wenton a low-salt diet, adherence to which was evaluated by analyzing the amount of saltin 24-hour urine collections. The authors found 56 trials and concluded that, in peoplewho had high blood pressure to start with, a reduction of salt intake of 2,400 mgs (or 6 grams of salt) resulted in an average reduction of systolic pressure of 3.7 mm Hg and of diastolic by less than 1 mm Hg. In people with normal blood pressure, there was no effect. The effect in the hypertensives was largely confined to older individuals (above the age of 45), who showed a reduction of 6.3 mm Hg of systolic and 2.2 mm Hg of diastolic pressure. Hypertensives below the age of 45 showed no blood pressure response.

        Doctor's comments:

This is the most definitive analysis of the effects of salt restriction on blood pressure to date. The message is clear: if you have high blood pressure and you're over the age of 45, restricting your salt intake may be worth trying, but if you're younger, or if your pressure is normal, you're probably wasting your efforts. To achieve the reductions of blood pressure described in the article, you would need to make a big change in your diet. The average daily salt intake in US adults is about 3,900 mgs (10  grams of salt), so a reduction of 2,400 mgs means you would have to cut your intake by nearly one half, to 1,500 mgs. The recommended daily intake (which is printed on food labels) is 2,400 mgs. Most of the salt we eat is in processed foods, so just throwing out the saltshaker won't do it. For the majority of people, whether hypertensive or not, restricting calories and fat is much more important than restricting salt.

Where it was published

Midgeley JP and others. Effect of reduced dietary sodium on blood pressure. A meta-analysis of randomized controlled trials. JAMA - Journal of the American Medical  Association 1996;275:1590.