Salt and other health outcomes
Scientists have hypothesized that salt intake levels may be associated with other, non-cardiovascular health consequences. Many have been examined.
Hyponatremia. Studies have confirmed the importance of a balance of electrolytes: sodium, calcium, potassium and magnesium. When the body loses electrolytes in perspiration or when suffering diarrhea or when the usual electrolyte balance is upset when rehydration includes only water and not salt and other electrolytes, “water intoxication” or hyponatremia occurs. Marathon runners are warned to make sure they consume extra salt and diarrhea is treated with Oral Rehydration Therapy to replace lost electrolytes. The consequences can be serious, even deadly.
Diabetes. When most people think of a white granule whose intake is important to maintaining insulin sensitivity, they, reflexively, think of sugar. But, actually, it is salt that plays a critical role. Our bodies need salt to maintain healthy levels of insulin. Low-salt diets impair insulin sensitivity, lowering the body’s tolerance of glucose (sugar) which triggers type 2 diabetes. Low-salt diets also increase sympathetic nerve activity and decrease tissue perfusions, two other factors worsened by insulin resistance. The key problem is that low-salt diets stimulate the production of renin and aldosterone with have multiple adverse (and always unintended) consequences.
Cancer. Studies in several societies with exceptionally high consumption of salted fish (e.g. coastal villages in Portugal and the traditional Japanese diet) have suggested that the very high level of salt intake irritates the stomach lining and increases the risk of gastric cancer. Further research should examine this question, but there is no evidence that suggests that salt intake levels in the typical “western” diet (e.g. in North America) are anywhere near levels of concern. The American Cancer Society has considered and dismissed this notion.
Asthma. Some have hypothesized that salt may impede lung function and be problematic for asthmatics or others with respiratory ailments. The Center for Science in the Public Interest claims “High-salt diets impair lung function and worsen asthma symptoms High-salt diets impair lung function and worsen asthma symptoms,” while World Action on Salt and Health goes so far as to state: “There is evidence that bronchial reactivity in people with asthma is linked with salt intake. A recent review of epidemiological and intervention studies demonstrated that reducing salt intake may help to reduce the severity of an asthma attack and other breathing problems.” The long-awaited definitive study of the question was published in June 2008, headlined: “Low-sodium advice for asthmatics should be taken with a pinch of salt. ” In short, science confirms salt is blameless with regard to asthma which further confirms the wisdom of many doctors who had routinely prescribed extended visits in salt mines for those suffering asthma and other respiratory diseases.
Osteoporosis. When it comes to over-interpreting the evidence, this issue may be the most salient example. Medical science well understands that sodium intake and calcium excretion are inversely related; that is, the more salt you eat, the more calcium you excrete. Since our bodies generally require more calcium than we ingest, the logical conclusion is that we could advantage our calcium status (and bone health) if we ate less salt. The relatively small amounts of calcium involved, however, support calls to eat a banana or drink a glass of milk as the best advice to improve calcium status.
Obesity. Included in this list only because anti-salt advocates continually call for reduction of this non-caloric ingredient in our diets. True, salt makes food taste good and people are more likely to eat more food that’s palatable than that they find bland and unappealing, but there is no metabolic association of salt intakes with the likelihood of developing obesity. None.