Question: My wife has high blood pressure, and she is on a salt-restrictive diet. She says I should eat less salt, too. If my blood pressure is normal, should I also be restricting how much salt I eat? I love salt.
Answer: Would you believe _ good news for a change. Salt restriction does not appear to be necessary, or perhaps even desirable, if you don't have high blood pressure. According to University of Toronto researchers who reanalyzed all published clinical trials involving salt and hypertension, no nasty consequences have been associated with salt consumption in people with normal blood pressure. These scientists now question the "wisdom of universal dietary sodium restriction without better evidence of the long-term benefits and safety of such an intervention." Safety is a concern since new evidence has linked low sodium intake with higher mortality risk and adverse metabolic effects.
The goal of having the population at large cut back on salt was part of the 1990 Nutrition Labeling and Education Act. This goal was based on the fact that people in non-Western populations who have low-salt diets don't get high blood pressure. In comparison, we typically eat five to 10 times more salt than our bodies need. High blood pressure (hypertension) affects 50-million people in the United States. And this disease is a major factor associated with heart attacks, strokes and artery disease.
While the Toronto researchers question the sodium reduction goal for people whose blood pressure is normal, there is no change in recommendations for people who are hypertensive (blood pressure greater than 140/90 millimeters of mercury). Although the role salt plays in hypertension is not clear (one theory is that it interferes with the ability of blood vessels to relax), salt restriction is still recommended for people with high blood pressure _ along with weight control, reduction in alcohol intake, not smoking and anti-hypertensive drugs as prescribed.
Finally, to be on the safe side, we should all use salt in moderation. Overuse of any nutrient seems to be unhealthy in the long run. Check all this out with your doctor.
Getting in tune
to your cycles
Question: I find that I generally have a better workout in the morning before breakfast than I do early in the afternoon. I jog and walk for about 40 minutes several days a week. Is there an explanation for this? And aside from heat concerns, is there any advantage to one time of day over another?
Answer: One reason for your morning workout preference may have to do with the 24-hour body clock (circadian rhythm) we live by. During sleep, our muscle activity nearly disappears and our metabolic rate, respiration, heart rate and blood pressure decrease. An hour or two before we wake, hormones are released by the body to prepare us for the day's activity. We all accept these physiological changes differently. Some people, like yourself, are ready to go as soon as they are out of bed. Others take several hours before they are even human.
A pre-breakfast workout may have an advantage in losing fat. During sleep, carbohydrates are being consumed by normal resting metabolic functions. By morning, this relatively small energy reserve is low. So, if you exercise before eating breakfast, your body adjusts by using more fat stores for energy. In addition, a cup of coffee before you start can further stimulate the burning of fat.
On the other hand, a noon exercise session seems to energize people who enjoy a break, a distraction, during the day. And there are those who prefer the evening and find exercising at that time helps them sleep better. Obviously, too, jobs and other responsibilities often dictate workout times to which we learn to adjust.
Patrick J. Bird, dean of the College of Health and Human Performance, University of Florida, draws on a data base of more than 3,800 medical, health and fitness journals in preparing answers to questions in his column. Write with questions to Dr. Bird, College of Health and Human Performance, University of Florida, Gainesville, FL 32611.