Lest we forget, the ongoing demonization of sugar by health advocates, who arguably have misused science to advance their cause, was preceded by another group of health advocates who said that the intake of salt should be greatly reduced as it too is associated with health risks. At the risk of being rhetorical, one would think public health strategies are based on evidence that holds up to critical scrutiny. New research on salt intake showing that “There is no convincing evidence that people with moderate or average sodium intake need to reduce their sodium intake for prevention of heart disease and stroke”1 is one such example.
This extensive study published in the reputed journal The Lancet, involved 94,000 people, aged 35 to 70, over a period of eight years in communities from 18 countries around the world. The findings showed that there is an associated risk of cardiovascular disease and strokes only where the average intake is greater than five grams of sodium a day. It is very reminiscent of the meta-analysis on dietary sugar and body weight published in the British Medical Journal (BMJ) by Te Morenga et al2. In that study, “their conclusion that sugars intake is a ‘determinant’ of body weight” could be applied equally to any caloric nutrient or food.
In his editorial3 in the BMJ, commenting on the study by Te Morenga and colleagues, Walter Willett, a professor of nutrition at the Harvard School of Public Health, pointed out that “the association between sugar and poor health has remained contentious over the past few decades.” A totally narrow focus on sugar is simply too limiting, as “Many starchy foods, particularly highly processed grains and potato products, have a high glycemic index, raising blood glucose and insulin more rapidly than an equivalent amount of sucrose.” He goes on to say that “Unfortunately, the 2003 WHO (World Health Organization) report disregarded evidence suggesting that refined grain and potato products have metabolic effects comparable to those of sugar.”
Just as the overtly prescriptive nature of the WHO’s recommendations on sugar intake4 has been questioned, the researchers involved in the salt study also dispute the organizations public health guidelines. “The World Health Organization recommends consumption of less than two grams of sodium — that’s one teaspoon of salt — a day as a preventative measure against cardiovascular disease, but there is little evidence in terms of improved health outcomes that individuals ever achieve at such a low level,” said Andrew Mente, first author of the study1, based at the Population Health Research Institute (PHRI) of McMaster University and Hamilton Health Sciences. Indeed, several researchers have echoed WHO’s shortcomings in a paper analysing their many reports, concluding that “Strong recommendations based on low or very low confidence estimates are very frequently made in WHO guidelines “.5
In a critique6 Edward Archer points out that while the likes of “the Food and Agriculture Organization of the United Nations and World Health Organization have repeatedly determined that human food energy requirements should be estimated using total daily energy expenditure, and that physical activity and basal energy expenditure are the primary determinants of this measure. Yet nutrition research rarely measures any form of energy expenditure or quantifies physical activity. This failure has led to a plethora of results that are suggestive of multiple and often divergent explanations, thereby obfuscating the examination of diet-health relationships.”
1 Andrew Mente, et al (2018) Urinary sodium excretion, blood pressure, cardiovascular disease, and mortality: a community-level prospective epidemiological cohort study. The Lancet, 2018; 392 (10146): 496 DOI: 10.1016/S0140-6736(18)31376-X
2 Te Morenga L, Mallard S, Mann JM (2013)“Dietary sugars and body weight: systematic review and meta-analysis of randomized controlled trials and cohort studies” British Medical Journal BMJ 2012;345:e7492 doi:101136/bmj.e7492
3 Walter Willett (2013) Science souring on sugar. British Medical Journal, (2013;346:e8077)
4 WHO guideline recommends adults and children reduce their daily intake of free sugars to less than 10% of their total energy intake. A further reduction to below 5% or roughly 25 grams (6 teaspoons) per day would provide additional health benefits.
5 Paul E. Alexander et al (2013) World Health Organization recommendations are often strong based on low confidence in effect estimates. Journal of Clinical Epidemiology, 67 (6): 629–634
6 Edward Archer, (2013) Wolf in sheep’s clothing. http://www.the-scientist.com/?articles.view/articleNo/37918/title/Opinion–A-Wolf-in-Sheep-s-Clothing/