The World Health Organization (WHO) has released a significant new guideline on non-sugar sweeteners (NSS), often referred to as artificial or low-calorie sweeteners, which advises against their use for controlling body weight or reducing the risk of noncommunicable diseases. This recommendation stems from a comprehensive research review that concluded replacing sugar with NSS does not lead to long-term weight loss in either adults or children. While some clinical trial data indicated a temporary reduction in calorie intake when NSS replaced sugar-sweetened foods and beverages, the long-term efficacy for weight management remains unsubstantiated. Furthermore, the guideline found no consistent effect of NSS on hunger or satiety levels, with some studies suggesting reduced hunger and others indicating a stronger appetite with higher NSS consumption.
The WHO’s comprehensive analysis incorporated data from a range of studies, including observational cohort studies. These studies revealed an association between the long-term consumption of NSS-containing beverages and an increased risk of cardiovascular disease and premature death in adults. Similarly, higher intakes of NSS, whether in beverages or added to foods, were linked to an elevated risk of developing type 2 diabetes. The organization acknowledged the potential for "reverse causation" in these observational findings, where individuals already predisposed to chronic diseases, such as those with higher body mass index (BMI) and obesity, might opt for NSS as a perceived healthier alternative, thus skewing the association. It is crucial to note that no association was found between NSS intake and cancer or cancer-related deaths.
Background and Timeline of the Guideline
The development of this guideline is part of the WHO’s ongoing efforts to provide evidence-based recommendations for public health. The decision to scrutinize NSS has been building for years, fueled by the widespread adoption of these products as sugar alternatives in response to growing concerns about sugar’s impact on health. In recent years, regulatory bodies and research institutions worldwide have intensified their focus on understanding the complex effects of NSS on human health, leading to a proliferation of studies.
The WHO’s guideline is the culmination of a systematic review of evidence, which included an extensive search and appraisal of randomized controlled trials (RCTs), non-randomized studies, and observational studies. The review process likely involved multiple stages of data extraction, synthesis, and expert consultation, spanning several months, if not years. The final guideline, released in July 2023, represents the most current and authoritative stance from the organization on this topic.
Key Findings and Recommendations
The core recommendation from the WHO is a proactive approach to reducing overall sweetness in the diet, emphasizing the importance of initiating these dietary habits early in life. The organization highlights that NSS do not contribute any nutritional value to the diet. The guideline specifically names common NSS such as acesulfame K, aspartame, saccharin, sucralose, and stevia. It is important to note that the analysis did not extend to sugar alcohols, also known as polyols, such as maltitol, xylitol, and sorbitol, which are frequently added to a wide array of food and beverage products.
Expert Perspectives and Criticisms
Experts from the Harvard T.H. Chan School of Public Health have largely concurred with the WHO’s recommendation to moderate sugar cravings. However, they have also offered some critical feedback regarding the meta-analysis. Specifically, they pointed out the exclusion of several large cohort studies from the WHO’s review. These omitted studies, which collectively involved over 100,000 participants, had indicated that increasing the consumption of artificially sweetened beverages in place of sugar-sweetened beverages was associated with reduced weight gain over time. This finding aligns with the results observed in smaller, short-term randomized controlled trials.
Based on statistical modeling of these excluded studies, it was estimated that substituting one serving of a sugar-sweetened beverage with an artificially sweetened one could be associated with a 4% lower risk of all-cause mortality, a 5% lower risk of cardiovascular disease-related mortality, and a 4% lower risk of cancer-related mortality. This suggests a potential nuance in the interpretation of NSS benefits, particularly in the context of transitioning away from sugar.
Optimal Beverage Choices for Long-Term Health
In the broader discussion of healthy hydration, experts emphasize that while NSS might serve as a temporary substitute for sugar-sweetened beverages, they are not the optimal choice for long-term health. Frank Hu, Chair of the Department of Nutrition at the Harvard T.H. Chan School of Public Health, articulated this perspective, stating, "For habitual consumers of sugar-sweetened beverages, artificially sweetened beverages can be used as a temporary replacement, although the best choices would be water and unsweetened coffee or tea." This underscores the consensus that plain water, unsweetened coffee, and unsweetened tea remain the gold standard for healthy beverage consumption.
Spotlight on Aspartame: A Closer Look at a Widely Used Sweetener
The recent deliberations surrounding NSS have also brought a specific focus on aspartame. In July 2023, the International Agency for Research on Cancer (IARC), a specialized agency of the WHO, alongside the Joint FAO/WHO Expert Committee on Food Additives (JECFA), released a risk assessment of aspartame and cancer. The IARC classified aspartame as a Group 2B carcinogen, meaning there is "limited evidence" of carcinogenicity in humans, specifically in relation to liver cancer.
However, it is critical to contextualize this classification. JECFA reaffirmed its previously established acceptable daily intake (ADI) for aspartame, which is 40 mg per kilogram of body weight. The committee stated that their research review did not provide evidence to alter this guideline, affirming that intake within this range is considered safe. For an individual weighing 150 pounds (approximately 68 kg), this ADI translates to a daily limit of roughly 2,727 mg of aspartame. This amount is equivalent to consuming about eleven 12-ounce cans of diet soda, as a single can typically contains around 250 mg of aspartame.
The IARC and JECFA explicitly noted that the evidence on cancer risk in humans, based on both animal and human studies, was not convincing enough to warrant a change in the ADI. They emphasized the need for more extensive research, particularly longer-term studies with robust follow-up and well-designed randomized controlled trials, to provide more definitive conclusions. This nuanced approach highlights the distinction between hazard identification (what could potentially cause harm) and risk assessment (the likelihood of harm occurring under specific exposure conditions).
Broader Implications for Public Health and Consumer Choices
The WHO’s guideline carries significant implications for public health policy, the food and beverage industry, and consumer behavior. For policymakers, it reinforces the need to promote dietary patterns that prioritize whole foods and limit added sugars and artificial ingredients. This could translate into updated dietary recommendations, public health campaigns, and potentially even regulatory measures related to food labeling and marketing.
The food and beverage industry will likely face pressure to reformulate products and explore healthier alternatives. The widespread availability of NSS-containing products has contributed to their prevalence in the market, and this new guidance may spur innovation in developing genuinely healthier options or promoting traditional beverages like water.
For consumers, the guideline serves as a call to re-evaluate their reliance on NSS. It encourages a mindful approach to dietary choices, emphasizing the long-term benefits of reducing overall sweetness and prioritizing nutrient-dense foods and beverages. The message is clear: while NSS might offer a temporary reprieve from sugar, they are not a panacea for weight management or disease prevention and may even be associated with certain health risks. The emphasis on early habit formation is particularly important, suggesting that fostering a preference for less sweet foods and drinks from childhood can have lasting positive impacts on health trajectories.
The complexity of the evidence, including the debate over excluded studies and the nuanced classification of aspartame, underscores the ongoing scientific inquiry into the effects of NSS. As research continues, consumers and health professionals alike will benefit from staying informed about evolving scientific understanding and making choices that align with the overarching goal of promoting sustainable health and well-being. The WHO’s latest guidance provides a crucial framework for this ongoing dialogue, advocating for a fundamental shift towards a less sweet, more wholesome dietary future.
