Feds disagree on bland diets.

For nearly two decades, the Federal government has supported a consensus that affects a common complaint of nursing home residents - bland food. Our blood pressure increases naturally as we get older, and it is thought that reducing or eliminating sodium, a major component of table salt, will reduce the risk of developing high blood pressure. For this reason, nursing homes often moderate the salt intake of all residents, who in turn often refuse to eat what's offered.

Now, though, the consensus that all Americans should limit their salt intake is under attack. At the very least, it appears that the premise of a low-salt diet being a good idea for all elderly Americans may not stand the test of science.

One source of the lack of consensus is the Federal government itself, in that there is no standard process to ensure that current scientific knowledge is reflected. Both the U.S. Department of Agriculture (USDA) and the U.S. Department of Health and Human Services (HHS) offer nutrition advice. Different HHS panels can also develop recommendations independently.

No one on any side of the salt controversy doubts that sodium reduction, combined with exercise, reduces blood pressure in older patients who have been diagnosed with hypertension. For example, a study reported last March in the Journal of the American Medical Association found that some 80-to-84-year-old hypertension patients reduced their blood pressure through monitored sodium restriction and weight loss. According to lead researcher Paul K. Whelton, MD, of Tulane University, the results are consistent with previous findings that roughly one-third of older hypertension patients can avoid blood-pressure medication by similar dietary changes.

Any statement about salt beyond this modest consensus, though, is open to scientific debate. A massive multinational study known as Intersalt, completed in 1988, found that salt intake is at best a minor factor in the onset of hypertension. In Japan, for example, where fish, salt-laden soy sauce, and pickled vegetables are staples, consumers average far more sodium intake than most Americans but face lower risk for high blood pressure. In 1997, a study funded by the National Institutes of Health used the Dietary Approaches to Stop Hypertension (DASH) diet, in which a very slight reduction in sodium was coupled with an increase in fruits and vegetables rich in calcium, potassium, and magnesium; its results were such that the American Heart Association endorsed DASH and its sodium target of 3,000 mg per day.

What about the bottom line question: does a low-salt diet promote long life? A recent series of studies authored by Michael H. Alderman, MD, president of the American Society of Hypertension, concluded that a low-salt diet is associated with a higher risk of early death in individuals with normal blood pressure in the overall population. Although it is possible that individuals on low-salt diets already have symptoms of chronic health problems that lead to their demise, researcher Daniel Rudman, MD, reportedly offered the suggestion that the elderly are more likely to live longer when offered food that matches their taste preferences.

This melange of research findings and interpretations has, not surprisingly, produced a chorus of conflicting Federal recommendations. For example, although the Dietary Guidelines issued by the HHS Office of Disease Prevention and Health Promotion refer to the Daily Value of 2,400 mg of sodium, as reported on the Food and Drug Administration's (FDA) Nutrition Facts Label, as reason for arguing that "Americans consume more salt than is needed," the FDA refers to the Daily Value as a "reference number" rather than a recommendation. In addition, the Dietary Guidelines point out "that there is no way at present to tell who might develop high blood pressure from eating too much sodium," alluding in this way to the absence of conclusive research that hypertension is ever caused by eating too much salt.

Meanwhile, the Joint National Committee on Hypertension (JNC), an advisory body of the National Heart, Lung, and Blood Institute, has declined to endorse limiting diets to 2,400 mg of sodium. According to JNC member Lee Green, MD, JNC recently replaced the use of consensus statements with an evidence-based process that relies less on the contributions of one or two specialists. The result, in 1997, was a report that focused on the proven need to detect and treat hypertension, without mandating dietary salt reduction for all Americans.

The latest forum for the debate over salt is the HHS-controlled development of a set of national health and wellness objectives called Healthy People 2010. Its predecessor, Healthy People 2000, issued in 1990, avoided setting a specific level for sodium intake but recommended that: 1) cooks avoid salt when preparing food, 2) Americans avoid adding salt to their food at the table, and 3) everyone shift their purchases to reduced-salt choices. During the public forums that are part of the Healthy People 2010 process, a few individuals have endorsed these recommendations, but more speakers have urged that salt intake objectives should be limited to older patients with existing hypertension. HHS officials, however, have stated that they do not intend to eliminate universal salt intake objectives.

Are HHS officials more interested in defending past recommendations than in acknowledging doubt on the wisdom of prescribing low salt diets to everyone? Healthy People 2010 may have abandoned the evidence-based policies advocated by Dr. Green and the JNC in favor of cautious recommendations lacking scientific support. Residents may continue to refuse to eat, and it may all be unnecessary.