Chapter 14
Lifestyle+ — 5
The story of nonnutritive, artificial sweeteners is a bit more complicated, with conflicting reports regarding the many nonsugar substances. A comprehensive review of all the available data from randomized and observational studies found a lack of compelling evidence for associated risk. In contrast, another large cohort of more than one hundred thousand people found a direct association between consuming such sweeteners, particularly aspartame, acesulfame potassium, and sucralose, with cardiovascular and cerebrovascular disease risk. But that was not the case when different artificial sweeteners were examined separately through a randomized trial. In 120 healthy adults given saccharin, sucralose, aspartame, and stevia, versus controls for two weeks, the first two sweeteners induced impaired glucose regulation (also known as glycemic response), and all four were associated with changes in the oral and gut microbiome. Previous work has shown that such alteration of the gut microbiome is tied to the abnormal glycemic response. Overall, the data for artificial sweeteners is unfavorable, although it is not nearly as worrisome as high sugar consumption. Certain sweeteners, such as stevia, appear to be less concerning than others.
Salt
While the magnitude of the effect is debated, the link of sodium intake to hypertension is clear. A review from the Cochrane Library of all available data from 195 interventions studies that compared low- versus high-sodium diets concluded the effect of restriction was small, with a decrease in mean blood pressure of only 0.4 mm Hg, slightly greater among Black and Asian participants. In treating innumerable patients for hypertension over a few decades, I’ve seen that reduction of dietary sodium can help reduce blood pressure, as confirmed in many studies, but the impact varies considerably and may be small in many. An extensive analysis of sodium intake suggested moderate consumption (1–2 teaspoons of salt; 2 g of sodium = 5 g of salt) was not a problem. But increased cardiovascular risk became obvious at levels of more than 5 grams of sodium per day. Recommendations from the American Heart Association, World Health Organization, and European Society of Cardiology vary considerably, from 1.5 grams to 2.25 grams per day. By the same metric, the average American’s intake is about 3.5 grams!
The risks from dietary sodium are not confined to high blood pressure. Multiple experimental model studies support high salt diet’s reduction of blood flow to the brain through dysfunction of the blood vessel wall (endothelium) and potential risk of cognitive impairment. The finding that people who consume the least amount of sodium have the lowest risk of cardiovascular disease has been backed up by other studies.
The best general advice for people with hypertension is to avoid or limit adding salt to foods, to keep an eye on overall intake by paying attention to food labels, and, when no kidney disease is present, to consider using a potassium chloride salt substitute. The evidence for salt substitute from a randomized trial of more than six hundred participants with normal blood pressure, average over seventy years of age, is encouraging—there was a 40 percent reduction of hypertension. A systematic analysis of the evidence for long-term salt substitution supported reduction of all-cause and cardiovascular mortality. The lower, the better is easy to say. I acknowledge Sir George Pickering’s perspective from 1961: “The rigid low-sodium diet is insipid, unappetizing, monotonous, unacceptable, and intolerable. To stay on it requires the asceticism of a religious zealot.”