Does too much salt in the diet cause high blood pressure? That question goes in and out of favor (yea or nay) among the medical community. It used to be standard wisdom that too much salt was bad for the vascular system (blood vessels) and specifically it caused higher blood pressure. Studies that are more recent have called this into question by opening the door on a genetic factor in the reaction to salt.
Some people react more strongly to salt than others. However, these and most other salt-diet studies were for adults. For children, the story has a different flavor. In a study conducted by Thomas Jefferson University (Philadelphia), it appears too much salt is definitely a trigger for high blood pressure (hypertension) in many children.
The researchers examined the medical records from the National Health and Nutrition Examination Survey for over 11,500 children, ages 8 through 17. They use data from two periods: 1988-1994 and 1999-2008 and looked for the relationship, if any, between high blood pressure and salt intake (i.e. a diet known to be high in sodium content).
In this case, the researchers found that more than 80 percent of the children had a daily sodium intake of 2,300 milligrams or more (often much more) – compared to the recommended daily consumption of no more than 1500 milligrams per day. The combined results of the study showed that children with the greatest sodium consumption were 36% more likely to have elevated blood pressure.
The background for this study is research and epidemiological evidence showing that while childhood obesity is, in fact, decreasing somewhat (at least in the U.S.), hypertension (high blood pressure) is becoming more common. Hypertension in children is, unfortunately, problematical for scientific research. Common sense and many studies show that like adults, hypertension is one of the conditions that may contribute to serious cardiovascular problems in children. However, with children the issue isn’t so much a matter of them developing immediate cardiovascular problems (stroke, atherosclerosis), but of its effects on their health 20 or more years later.
Added to that is the problem of relatively extreme variations among young people in the response to hypertension by age, sex, body build (namely, BMI – body mass index), and general health. Since salt is only one of the potential factors in hypertension, these variations make pinning a label on salt such as “causes high blood pressure and adverse cardiovascular health” questionable.
This does not mean that high salt intake for children is either “a good thing” or “a neutral thing,” it only means that precise linkages – say, consuming more than 3500 milligrams of salt a day – is probably not an accurate way to portray the issue.
What many researchers and medical nutrition specialists are now saying is that children (as well as adults) should learn to avoid foods that radically jump the daily intake of salt. This means, for example, that eating just one bag of potato chips (8 oz.) increases salt intake by over 1,000 milligrams. Add to that a meal or two of fast food (pizza slice – 600+ milligrams) or processed food (mac & cheese serving, box mix – 900 milligrams) and the daily intake can easily be over 4,000 – 5,000 milligrams. If the child is already tending toward overweight (high BMI) and perhaps has other less than healthy habits (e.g. low exercise), the odds increase rapidly that the high salt intake will be part of a pattern leading to hypertension.
Prolonged hypertension, especially in young people, has a poorly predictable – but usually negative – long-term impact on their health.
The new genetic research on salt, for example the groundbreaking work at the University of Virginia (Roanoke), used a Phase II clinical trial to show that in a study group of 183 people, about 25% are salt sensitive, 64% are salt neutral (not much reaction to salt levels), and perhaps surprisingly, 11% are “inverse salt reactive” – low salt in the diet causes high blood pressure.
The research also identified a gene – a salt sensitivity gene – that may indicate which people are more likely to react negatively to salt than others. Far more research is needed in this direction, but it is moving toward an understanding of salt and an individual’s sensitivity, rather than the current more broad-brush (generalized) positions.