Aspartame safety, industry funding bias, and research reliability

Aspartame is an artificial sweetener, sold most commonly under the brand names NutraSweet and Equal. It is hundreds of times sweeter than natural sugars, making it possible to sweeten food and pharmaceutical preparations without the addition of any sugar, rendering the product a viable solution for persons with diabetes and other conditions in which sugar consumption is contraindicated or when reduced caloric intake is recommended. Although the product has no direct health benefits, it does have indirect benefits as a means whereby people who have or who are at risk for diabetes, obesity, and other diet-related diseases can minimize sugar intake without having to change their lifestyle in any appreciable way. Research into the adverse health impacts of long-term and/or high quantities of aspartame is controversial, problematic, and generally inconclusive.

Manufactured by bonding amino acids aspartic acid and phenylalanine, aspartame is most commonly sold under the brand names Equal and NutraSweet (American Cancer Society, 2014). It has been approved for use in human foods since the 1980s. The American Cancer Society, the Food and Drug Administration, and the European Food Safety Authority (EFSA) have all declared aspartame to be safe for human consumption in spite of the fact that a large number of peer-reviewed studies have shown a link between aspartame and carcinogenesis or aspartame consumption and instances of cancers.

Meta-analyses of aspartame-related research reveal methodological problems with some of the peer-reviewed studies, as well as biases such as conflicts of interest in the source funding for those studies. Walton (2014) conducted a survey of 166 studies on aspartame with "direct relevance for questions of human safety" and found that a full hundred percent of the studies funded by companies that manufacture aspartame (such as NutraSweet) "attested to aspartame's safety," whereas 92% of independently-funded research "identified a problem" related to the safety of the product for human consumption. The number of independent studies confirming some adverse health impacts of aspartame shoots to 100% if no FDA funded literature is included. Walton (2014) also notes that research funded by the aspartame industry and its stakeholders refers regularly to studies of "questionable validity and relevance," and other methodological concerns (p. 1). Therefore, significant caution should be taken when consuming products containing aspartame or recommending these products to patients.

Some research studies may suggest that the potential dangers of aspartame are outweighed by the benefits in specific populations. Specifically, persons with chronic diabetes and obesity may need to rely on aspartame and other "low calorie sweeteners" to keep blood sugar levels as low as possible or to maximize weight loss (Asif, 2012, p. 1). Yet aspartame can also be considered a shortcut to achieving health-related goals in populations that have the potential to avoid foods containing either aspartame or refined sugars. Aspartame is an unnecessary additive in the diet, largely because the products that contain it (such as diet sodas, sweeteners for coffee, or processed snack foods) are unnecessary in and of themselves. Persons needing to control their diet are urged to more rigorously apply the standards of good nutrition and lifestyle habits rather than rely on artificial sweeteners to achieve healthcare goals.

In fact, one of the problems with overreliance on aspartame and other artificial sweeteners is that these products are "added to foods that have considerably reduced caloric content and, thus, may be consumed in large amounts, (Woodrow, n.d., p. 1). The amounts of aspartame consumed throughout the course of a day and over time in vulnerable populations may exceed their recommended safety allowances. As Woodrow (n.d.) points out, aspartame releases "into the human bloodstream one molecule of methanol for each molecule of aspartame consumed," and thus "when diet sodas and soft drinks, sweetened with aspartame, are used to replace fluid loss during exercise and physical exertion in hot climates, the intake of methanol can exceed 250 mg/day or 32 times the Environmental Protection Agency's recommended limit of consumption for this cumulative toxin," (p. 1). Therefore, artificial sweeteners should not be considered a normative or recommended course of action for persons needing to minimize sugar intake, minimize blood sugar measures, or maximize weight gain.

Given the caveats against its use, aspartame could still be considered safe based on the parameters used by major industry professionals and especially by stakeholders like food and drug manufacturers. The actual health outcomes in human beings who consume aspartame have been notoriously difficult to measure, and many studies suffer from methodological issues. Research has remained inconsistent on the effects of aspartame on specific diseases including vascular events and various forms of cancer (Marinovich, et al., 2013). Some meta-analyses contradict those made by Walton (2014), showing instead that aspartame and other artificial sweeteners are not linked to "common neoplasms" and cancers (p. 40). However, Soffritti, et al. (2007) found that when Sprague-Dawley rats consume aspartame at doses "close to the acceptable daily intake for humans," the rats exhibit a "significant increase in incidence of lymphomas and leukemias," and that carcinogenic effects are increased when the substance is introduced neonatally (p. 1293). Earlier research by Soffritti et al. (2006) found that even at a daily dose of 20mg/kg of body weight, which is "much less than the current acceptable daily intake," aspartame is a "multipotential carcinogenic agent," (p. 379). Researchers like these urge for a prompt re-evaluation of the current guidelines for aspartame consumption. Current guidelines in both Europe and the United States remain at 40mg/kg of body weight per person, an amount that is present in about 12 cans of diet soft drinks. Most people do not consume their daily allowance, but there will be some people whose dietary habits need to be more closely monitored in order to prevent overconsumption of a substance that is potentially carcinogenic at high doses. Furthermore, some diseases and conditions may increase the risk factors associated with aspartame intake. A rare hereditary disease known as phenylketonuria renders the person unable to metabolize aspartame, and the product should be expressly avoided by this cohort (American Cancer Society, 2014).