Intra-uterine exposure to saccharin and risk of bladder cancer in man

Association of Artificially Sweetened Beverage Consumption and Urinary Tract Cancers in the Women's Health Initiative Observational Study

Background

Insufficient data exist to conclude whether consumption of artificially sweetened beverages is associated with a higher risk of urinary tract cancers.

Objective

We sought to investigate whether urinary tract cancer incidence differed among women who consumed various amounts of artificially sweetened beverages.

Design setting and participants

This was a secondary analysis of data from the Women's Health Initiative Observational Study, a multicenter longitudinal prospective study of the health of 93 676 postmenopausal women with a mean follow-up time of 13.5 yr. Women were identified at 40 clinical centers across the USA and enrolled from 1993 to 1998. Women between the ages of 50 and 79 yr were enrolled. We included women who answered questions about artificially sweetened beverage consumption and reported no prior urinary tract cancer diagnoses. The frequency of artificially sweetened beverage consumption was categorized as follows: rare artificially sweetened beverage consumption (never to fewer than one serving per week), frequent consumption (one to six servings per week), and daily consumption (more than one servings per day).

Outcome measurements and statistical analysis

The incidence of urinary tract cancer reported during subsequent visits until February 28, 2020 was recorded. Demographic characteristics were compared between those with varying levels of artificially sweetened beverage consumption. Descriptive statistics were used to report the rates of urinary tract cancer diagnosis, and Cox regression models were constructed to determine hazard ratios and adjust for potential confounders.

Results and limitations

We identified 80 388 participants who met the inclusion criteria. Most participants (64%) were infrequent consumers of artificially sweetened beverages, with 13% (n = 10 494) consuming more than one servings per day. The incidence of urinary tract cancers was low, with only 804 cases identified. Cox regression models showed that frequent artificially sweetened beverage consumption was associated with a higher risk of kidney cancer (adjusted hazard ratio 1.34, 95% confidence interval 1.03-1.75). There was no significant association between artificially sweetened beverage intake and bladder cancer.

Conclusions

Frequent consumption of artificially sweetened beverages may be associated with a higher risk of kidney cancer among postmenopausal women.

Patient summary

A secondary analysis of the Women's Health Initiative Observational Study showed that higher consumption of artificially sweetened beverages was associated with a higher risk of kidney cancer.

Health outcomes of non-nutritive sweeteners: analysis of the research landscape

BACKGROUND

Food products containing non-nutritive sweeteners (NNSs) instead of sugar have become increasingly popular in the last decades. Their appeal is obviously related to their calorie-free sweet taste. However, with the dramatic increase in their consumption, it is reasonable and timely to evaluate their potential health benefits and, more importantly, potential adverse effects. The main aim of this scoping review was to map the evidence about health outcomes possibly associated with regular NNS consumption by examining the extent, range, and nature of research activity in this area.

METHODS

We systematically searched Ovid MEDLINE, EMBASE and the Cochrane CENTRAL databases for studies on NNSs (artificial sweeteners or natural, non-caloric sweeteners, either used individually or in combination) using text terms with appropriate truncation and relevant indexing terms. All human studies investigating any health outcomes of a NNS intervention or exposure were eligible for inclusion. No studies were excluded based on language, study design or methodological quality. Data for each health outcome were summarized in tabular form and were discussed narratively.

RESULTS

Finally, we included 372 studies in our scoping review, comprising 15 systematic reviews, 155 randomized controlled trials (RCTs), 23 non-randomized controlled trials, 57 cohort studies, 52 case-control studies, 28 cross sectional studies and 42 case series/case reports. In healthy subjects, appetite and short term food intake, risk of cancer, risk of diabetes, risk of dental caries, weight gain and risk of obesity are the most investigated health outcomes. Overall there is no conclusive evidence for beneficial and harmful effects on those outcomes. Numerous health outcomes including headaches, depression, behavioral and cognitive effects, neurological effects, risk of preterm delivery, cardiovascular effects or risk of chronic kidney disease were investigated in fewer studies and further research is needed. In subjects with diabetes and hypertension, the evidence regarding health outcomes of NNS use is also inconsistent.

CONCLUSIONS

This scoping review identifies the needs for future research to address the numerous evidence gaps related to health effects of NNSs use.It also specifies the research questions and areas where a systematic review with meta-analyses is required for the proper evaluation of health outcomes associated to regular NNSs consumption.

Occurrence of artificial sweeteners in human liver and paired blood and urine samples from adults in Tianjin, China and their implications for human exposure

In this study, acesulfame (ACE), saccharin (SAC) and cyclamate (CYC) were found in all paired urine and blood samples collected from healthy adults, with mean values of 4070, 918 and 628 ng mL(-1), respectively, in urine and 9.03, 20.4 and 0.72 ng mL(-1), respectively, in blood. SAC (mean: 84.4 ng g(-1)) and CYC (4.29 ng g(-1)) were detectable in all liver samples collected from liver cancer patients, while ACE was less frequently detected. Aspartame (ASP) was not found in any analyzed human sample, which can be explained by the fact that this chemical metabolized rapidly in the human body. Among all adults, significantly positive correlations between SAC and CYC levels were observed (p < 0.001), regardless of human matrices. Nevertheless, no significant correlations between concentrations of SAC (or CYC) and ACE were found in any of the human matrices. Our results suggest that human exposure to SAC and CYC is related, whereas ACE originates from a discrete source. Females (or young adults) were exposed to higher levels of SAC and CYC than males (or elderly). The mean renal clearance of SAC was 730 mL per day per kg in adults, which was significantly (p < 0.001) lower than those for CYC (10 800 mL per day per kg) and ACE (10 300 mL per day per kg). The average total daily intake of SAC and ACE was 9.27 and 33.8 μg per kg bw per day, respectively.

Systematic review of the relationship between artificial sweetener consumption and cancer in humans: analysis of 599,741 participants

BACKGROUND

The effect of artificial sweetener consumption on cancer risk has been debated in animal models for over four decades. To further investigate this relationship, this study aims to synthesise results from several of the most recent studies in humans.

METHODS

An online literature search was performed in MEDLINE from 2003 to 2014 using Ovid, PubMed, Web of Science, and Scopus using keywords 'artificial', 'sweetener' and 'cancer'. Ninety-two results were then manually assessed for eligibility. Studies were included if the relationship between artificial sweeteners and cancer was their central hypothesis, and if they adjusted for age, gender, smoking status and body mass index. Extracted data included study design, patient characteristics, outcome measure and results.

RESULTS

In the five publications that satisfied the inclusion criteria, significant direct associations with artificial consumption were found for laryngeal (odds ratio, OR 2.34, 95% CI: 1.20-4.55), urinary tract tumours (OR 2.12, 95% CI: 1.22-3.89), non-Hodgkin lymphoma in men (RR 1.31, 95% CI: 1.01-1.72), multiple myeloma in men (RR 2.02, 95% CI: 1.20-3.40) and leukaemia (RR 1.42, 95% CI: 1.00-2.02). Inverse relationships were found in breast (OR 0.70, 95% CI: 0.54-0.91, p trend = 0.015) and ovarian (OR 0.56, 95% CI: 0.38-0.81, p trend < 0.001) cancers.

CONCLUSION

The statistical value of this review is limited by the heterogeneity and observational designs of the included studies. Although there is limited evidence to suggest that heavy consumption may increase the risk of certain cancers, overall the data presented are inconclusive as to any relationship between artificial sweeteners and cancer.

Artificial sweeteners--do they bear a carcinogenic risk?

Artificial sweeteners are added to a wide variety of food, drinks, drugs and hygiene products. Since their introduction, the mass media have reported about potential cancer risks, which has contributed to undermine the public's sense of security. It can be assumed that every citizen of Western countries uses artificial sweeteners, knowingly or not. A cancer-inducing activity of one of these substances would mean a health risk to an entire population. We performed several PubMed searches of the National Library of Medicine for articles in English about artificial sweeteners. These articles included 'first generation' sweeteners such as saccharin, cyclamate and aspartame, as well as 'new generation' sweeteners such as acesulfame-K, sucralose, alitame and neotame. Epidemiological studies in humans did not find the bladder cancer-inducing effects of saccharin and cyclamate that had been reported from animal studies in rats. Despite some rather unscientific assumptions, there is no evidence that aspartame is carcinogenic. Case-control studies showed an elevated relative risk of 1.3 for heavy artificial sweetener use (no specific substances specified) of >1.7 g/day. For new generation sweeteners, it is too early to establish any epidemiological evidence about possible carcinogenic risks. As many artificial sweeteners are combined in today's products, the carcinogenic risk of a single substance is difficult to assess. However, according to the current literature, the possible risk of artificial sweeteners to induce cancer seems to be negligible.

Position of the American Dietetic Association: use of nutritive and nonnutritive sweeteners

Sweeteners elicit pleasurable sensations with (nutritive) or without (nonnutritive) energy. Nutritive sweeteners (eg, sucrose, fructose) are generally recognized as safe (GRAS) by the Food and Drug Administration (FDA), yet concern exists about increasing sweetener intakes relative to optimal nutrition and health. Dietary quality suffers at intakes above 25% of total energy (the Institutes of Medicine's suggested maximal intake level). In the United States, estimated intakes of nutritive sweeteners fall below this, although one in four children (ages 9 to 18 years) can surpass this level. Polyols (sugar alcohols), GRAS-affirmed or petitions filed for GRAS, add sweetness with reduced energy and functional properties to foods/beverages and promote dental health. Five nonnutritive sweeteners with intense sweetening power have FDA approval (acesulfame-K, aspartame, neotame, saccharin, sucralose) and estimated intakes below the Acceptable Daily Intake (level that a person can safely consume everyday over a lifetime without risk). By increasing palatability of nutrient-dense foods/beverages, sweeteners can promote diet healthfulness. Scientific evidence supports neither that intakes of nutritive sweeteners by themselves increase the risk of obesity nor that nutritive or nonnutritive sweeteners cause behavioral disorders. However, nutritive sweeteners increase risk of dental caries. High fructose intakes may cause hypertriglyceridemia and gastrointestinal symptoms in susceptible individuals. Thus, it is the position of The American Dietetic Association that consumers can safely enjoy a range of nutritive and nonnutritive sweeteners when consumed in a diet that is guided by current federal nutrition recommendations, such as the Dietary Guidelines for Americans and the Dietary References Intakes, as well as individual health goals. Dietetics professionals should provide consumers with science-based information about sweeteners and support research on the use of sweeteners to promote eating enjoyment, optimal nutrition, and health.

Lifestyle issues and genitourinary tumours

A variety of lifestyle factors, including physical activity, artificial sweeteners, alcohol consumption and smoking, have been reported to contribute to the risk of developing urological malignancies. A great number of epidemiological studies suggest that sports and physical activity may have a preventive influence on genitourinary tumours, especially on the incidence of prostate cancer. Smoking appears to be the most relevant lifestyle factor significantly increasing both incidence and mortality from bladder cancer. Furthermore, there is evidence implicating an association between tobacco use and kidney cancer. In contrast, prostate and testicular cancers are unlikely to be linked to tobacco use. As far as alcohol is concerned, most studies indicate that neither amount nor type of alcohol seems to be clearly associated with a risk of developing urological malignancies. However, some more recent cohort studies suggest a moderately increased risk for prostate and bladder cancer for specific types of alcohol. On the other hand, there is evidence that moderate alcohol consumption may even protect women from developing renal cancer. Since the introduction of artificial sweeteners, reports of potential cancer risks have circulated periodically through the mass media. The wide distribution of these agents and the fact that mostly combinations of the different compounds are added to a broad variety of food, drinks, drugs, and hygiene products complicates a systematic analysis of their potential impact on the development of urological malignancies. Nevertheless, so far not a single study has convincingly demonstrated a statistically significant risk of bladder cancer due to the consumption of artificial sweeteners. This survey demonstrates that the individual assessment of lifestyle factors not only may identify groups with an increased risk for urological malignancies but also clearly displays a potential for tumour prevention.

Saccharin mechanistic data and risk assessment: urine composition, enhanced cell proliferation, and tumor promotion

Sodium saccharin (NaSac) produces bladder tumors consistently in male rats only after lifetime exposure that begins at birth. NaSac is not metabolized and is negative in most genotoxicity tests. NaSac-induced cell damage and proliferation have been proposed as important factors in tumor promotion, and dose-response information demonstrating a threshold for these parameters is available. One theory proposes that high levels of NaSac, combined with protein in a high Na+, high pH environment found only in the male rat, form toxic microscopic crystals; therefore, NaSac-induced tumors may not be relevant to human carcinogenesis.

The effect of saccharin on the microbial metabolism of tryptophan in man

The microbial catabolism of tryptophan to indole has been studied in 15 human subjects by analysis of the daily urinary excretion of indican (potassium indoxylsulphate) before, during and after chronic saccharin ingestion. The daily excretion of indican during a 3-wk control period showed marked inter- and intra-subject variability. Analysis of the urinary excretion of saccharin during chronic administration demonstrated good compliance for both saccharin ingestion and urine collection. The urinary excretion of indican was not increased significantly by the ingestion of saccharin (1 g/day as divided doses with meals) for one month. These findings are consistent with epidemiology studies which show the absence of a consistent excess risk of cancer of the urinary bladder in humans ingesting saccharin as a food additive.

A review of epidemiological studies on artificial sweeteners and bladder cancer

Next to tobacco, saccharin may be the substance that has been most studied epidemiologically. Over 5000 patients with bladder cancer have participated in case-control studies; over 27,000 diabetics have been observed for 234,000 person-years. The summary relative risk from combining all case-control studies is less than 0.98, the standardized mortality ratio for bladder cancer in diabetics is only 70. Analysis of these studies leads to the conclusion that saccharin is not related to human bladder cancer.

Effects on mouse embryos of in utero exposure to saccharin: teratogenic and chromosome effects

For teratogenesis studies, pregnant ICR albino mice were administered saccharin by three routes and at three different doses by each route as follows: Intraperitoneal injection of 500, 1,000, or 2,000 mg/kg saccharin on day 10 of gestation; intragastric tube delivery of 5, 10, or 25 mg/kg/day of saccharin on days 5-15 of gestation; and as drinking water containing a 5, 10, or 20% solution of saccharin from day 0 through day 17. Appropriate controls were used for each set. No increase in either resorptions or malformations was found in mouse embryos whose dams had received saccharin by any of the three routes. For chromosome studies, saccharin was administered IP to pregnant ICR albino mice on day 10 of gestation as either a 1,000 mg/kg or 2,000 mg/kg dose. To demonstrate sister chromatid exchanges (SCE), bromodeoxyuridine was administered as 16 consecutive half-hourly doses of 25 mg/kg during the 8 h prior to saccharin injection. In addition, one group received two doses of BrdU and 2,000 mg/kg saccharin 8 h apart to demonstrate SCE frequency following exposure to saccharin for two cell cycles. The mice were given colchicine (4 mg/kg) 6 h after the final injection and killed 2 h later. Embryonic cell suspensions and metaphase spreads were prepared by routine methods. Metaphase spreads were examined for breaks or gaps (after Giemsa staining), for G-banding (using the ASG technique), for C-banding (using Giemsa staining after exposure to 0.07 N NaOH and incubation in 2 X SSC at 60 degrees C), and for SCE by the Hoechst-Giemsa method. Fifty metaphase spreads were counted for each experimental condition.(ABSTRACT TRUNCATED AT 250 WORDS)

Saccharin: a toxicological and historical perspective

Saccharin, first synthesized in 1879, eventually became popular as an inexpensive substitute for sugar, particularly as a non-caloric sweetner. The dispute concerning the safety of saccharin for human consumption is almost as old as saccharin itself. In this article, the history concerning the uses of saccharin and the accompanying controversy are reviewed. In addition, the spectrum of toxicological and epidemiological studies to which saccharin has been subjected are also examined. While the toxicological data indicate that saccharin is probably the agent solely responsible for the bladder tumors observed in second generation male rats, the epidemiological studies provide, at best, an equivocal relationship between the consumption of saccharin and bladder cancer. A benefit-risk evaluation for saccharin showed few, if any documentable benefits from the use of saccharin and much genuine uncertainty concerning the potential risks for ingestion by man. This element of genuine uncertainty as to the extent of human risk posed to man is the crux of saccharin's past and its foreseeable future.