Do Sodas Cause Cancer? What the Science Says

Drinking sugar-sweetened soda regularly is associated with a modest but real increase in cancer risk, according to multiple large studies and meta-analyses. The effect is not dramatic for any single can, but it compounds with volume and years of consumption. A systematic review pooling prospective studies found that higher soda intake raised overall cancer risk by about 10% compared with little or no intake, with stronger signals for specific cancers like those of the liver, breast, and colon. The picture is messier for diet sodas, where the evidence tilts toward no clear link but a few studies have raised flags about specific sweeteners. What makes the soda-cancer relationship hard to pin down is that sugar-sweetened drinks probably do not cause cancer through a single pathway.

What the Large Studies Actually Found

The most-cited study on this topic followed over 100,000 French adults in the NutriNet-Santé cohort. For every additional 100 milliliters of sugary drinks consumed per day (less than half a standard can), the risk of developing any cancer rose by about 18%. Breast cancer risk rose by roughly 22% per 100 mL/day increase. Artificially sweetened beverages showed no such association in that analysis.¹ Those are hazard ratios from a single cohort, not a final verdict, but they are consistent with what other studies have found.

A broader dose-response meta-analysis pooling multiple prospective studies confirmed the pattern: each additional standard serving of sugar-sweetened beverages per day was tied to a roughly 17% higher overall cancer risk. The relationship was dose-dependent, meaning the more someone drank, the higher the risk climbed. The researchers also identified a nonlinear curve, where risk accelerated at higher consumption levels rather than rising at a steady rate.²

A separate meta-analysis focused on individual cancer types found that each additional daily serving of sugary drinks raised overall cancer risk by about 4%, while the same amount of fruit juice raised it by about 14%. The analysis flagged breast cancer, liver cancer, colorectal cancer, and prostate cancer as the types most consistently linked to sugary beverage intake.³ The fruit juice finding often surprises people, but from a metabolic standpoint, the body processes a glass of orange juice and a can of soda in similar ways once the sugar hits the liver.

Which Cancers Show the Strongest Signals

Not every cancer type responds equally. The evidence is strongest for a handful of specific sites, and weaker or absent for others.

Liver cancer stands out. In a large U.S. cohort of over 90,000 postmenopausal women, those who drank one or more sugar-sweetened beverages per day had roughly 85% higher liver cancer risk compared with women who consumed three or fewer servings per month. They also had a 68% higher risk of dying from chronic liver disease.⁴ The liver connection makes biological sense: fructose is metabolized almost entirely in the liver, and chronic high intake promotes fat buildup there, a condition that can progress toward cancer over time.⁵

Colorectal cancer evidence is mixed but includes one striking finding about younger adults. A study tracking over 95,000 women in the Nurses’ Health Study II found that those who drank two or more sugary drinks per day had more than double the risk of early-onset colorectal cancer compared with women who drank less than one per week. Even intake during adolescence mattered: each daily serving of sugary drinks consumed between ages 13 and 18 was linked to a 32% higher risk of developing colorectal cancer before age 50.⁶ A pooled analysis of older cohorts, however, found no significant link between sugar-sweetened soft drinks and colon cancer overall, suggesting the association may be stronger in younger populations or that it takes specific patterns of long-term heavy consumption to move the needle.⁷

For breast cancer, results split depending on the study. The NutriNet-Santé cohort found a significant positive link, and a systematic review and meta-analysis confirmed a small but statistically significant association for sugar-sweetened drinks, with about a 14% higher risk among higher consumers.⁸ Two large U.S. prospective cohorts (the Nurses’ Health Studies), however, found no overall breast cancer association with sugar-sweetened beverages, though they did observe a modest link in lean women specifically.⁹ This kind of disagreement is common in nutritional epidemiology and probably reflects real differences in how populations eat, how body weight modifies the relationship, and how researchers adjust for confounders.

A large prospective study in Singapore found that drinking two or more soft drinks per week was tied to an 87% higher risk of pancreatic cancer, a dramatic-sounding number that should be read cautiously given the relatively small number of pancreatic cancer cases in the study.¹⁰ The same meta-analysis that flagged breast and prostate cancer also noted a trend toward higher pancreatic cancer risk with sugary drinks, though it did not reach statistical significance.⁸

On the other end, some cancer types show essentially no connection. The Cancer Prevention Study-II found no association between regular soda and non-Hodgkin lymphoma risk in men or women.¹¹ A separate analysis from the same cohort found that the link between sugary drinks and obesity-related cancers combined largely disappeared after adjusting for body mass index, except for colorectal and kidney cancers, which stayed significant.¹² That last detail matters: it hints that some of soda’s cancer risk works through making people gain weight, while some operates independently of weight.

Why Liquid Sugar Might Be Worse Than the Same Sugar in Food

You might wonder why soda gets singled out when sugar is everywhere. The answer has to do with how the body handles a rapid flood of fructose versus a slower trickle from solid foods. When you eat an apple, the fiber slows down absorption. When you drink a soda, fructose arrives at the liver in a concentrated burst, triggering fat production in the liver and driving insulin resistance more aggressively than the same amount of sugar eaten in solid form.¹³ This metabolic stress promotes inflammation and creates conditions favorable for tumor growth over time.

The gut microbiome adds another layer. Animal studies have shown that combining a high-sugar liquid diet with a high-fat diet reshapes the gut bacterial community in ways that favor species linked to inflammatory bowel disease, while ramping up inflammatory immune cells and pro-inflammatory signaling.¹⁴ Chronic gut inflammation is a known risk factor for colorectal cancer, which helps explain why the early-onset colorectal cancer link with soda has attracted so much attention.

Fructose metabolism in the small intestine is also getting fresh scrutiny. Recent research has shown that the small intestinal microbiota metabolizes sugars in ways that can produce toxic byproducts, distinct from the beneficial fermentation of complex carbohydrates that happens further along in the colon.¹⁵ None of this definitively proves that soda causes cancer through these pathways, but the biological plausibility is strong enough that researchers take the epidemiological associations seriously.

The Diet Soda Question

If sugar is the villain, switching to diet soda should eliminate the risk. The evidence mostly supports that logic, but with some caveats that keep the debate alive.

A meta-analysis of case-control studies found that artificial sweetener consumption overall was not associated with increased cancer risk. In fact, it found a decreased risk of urinary system cancers in women who consumed artificial sweeteners.¹⁶ However, a large French cohort study found that aspartame specifically was linked to about a 15% higher overall cancer risk and a 22% higher breast cancer risk among higher consumers, with acesulfame-K showing a similar pattern.¹⁷ A pooled analysis of prospective studies also found higher cancer incidence with artificial sweetener intake in European populations, along with a possible J-shaped curve for all-cause mortality, where moderate consumers had the lowest risk and heavy consumers had higher risk.¹⁸

A dose-response meta-analysis of artificially sweetened beverage intake found one specific signal worth noting: a positive linear association with leukemia risk, with each daily serving linked to about a 15% increase.¹⁹ That finding comes from a limited number of studies and needs replication, but it illustrates why researchers do not simply declare diet sodas safe and move on.

The sucralose story is a good example of how contentious this gets. A single lifetime rodent study from Italy’s Ramazzini Institute reported that mice fed sucralose developed blood cancers at higher rates. But independent pathologists have argued that the study had serious design flaws and that the findings are not reliable evidence of a cancer hazard in humans.²⁰ Major regulatory agencies including the FDA have maintained that sucralose is safe at current intake levels, and the broader toxicological evidence for most approved sweeteners does not point to carcinogenicity at the amounts people actually consume.²¹

Chemicals in Sodas Beyond the Sugar

Sugar and artificial sweeteners get most of the headlines, but sodas contain other compounds that have drawn separate concerns.

Caramel coloring, the ingredient that makes colas dark brown, can contain a byproduct called 4-methylimidazole (4-MEI), which forms during the manufacturing process. California has classified 4-MEI as a possible carcinogen and imposed strict exposure limits, while European regulators have found the evidence for genotoxicity insufficient to justify similar limits.²² A quantitative risk assessment found that regular soda drinkers can be exposed to meaningful levels of 4-MEI, though the actual cancer risk from that exposure remains debated.²³

Benzene is another concern, though it is more relevant to certain vitamin-fortified drinks than to standard colas. When sodium benzoate (a common preservative) and ascorbic acid (vitamin C) are both present in a beverage, they can react to form benzene, a known carcinogen. Lab experiments have shown benzene formation increases significantly when such drinks are heated, with concentrations reaching levels well above what most countries consider acceptable for drinking water.²⁴ Most major soda brands have reformulated to avoid this combination, but it can still show up in off-brand or imported products.

Canned sodas also raise the issue of bisphenol A (BPA), an endocrine-disrupting chemical that can migrate from the epoxy lining of aluminum cans into the beverage. BPA and its analogs have been linked to reproductive and metabolic disruptions.²⁵ Testing has detected BPA in canned carbonated beverages, with concentrations increasing when cans are exposed to heat.²⁶ While BPA’s cancer risk in humans at dietary exposure levels is still unresolved, the endocrine-disrupting effects are well documented enough that many manufacturers have moved toward BPA-free can linings, though the replacement chemicals (BPS, BPF) have their own concerns.

How Much Is Too Much

The dose-response data suggest there is no sharp threshold below which sugar-sweetened beverages are clearly safe for cancer risk. The relationship is more of a gradient. One meta-analysis found that each additional 250 mL per day (about one standard glass) of sugary drinks raised overall cancer risk by about 17%, stroke risk by 9%, and all-cause mortality by 7%.² The curve for cancer risk was nonlinear in that analysis, meaning the risk ramps up faster at higher consumption levels. Someone drinking a soda with dinner every night faces a meaningfully different risk profile than someone who has one occasionally at a birthday party.

This is relative risk, not absolute risk. Cancer is still relatively uncommon in any given year, so a 17% increase on a small baseline number remains a small absolute number. But across populations of millions of regular soda drinkers, even small relative risk increases translate to thousands of additional cancer cases.

The Industry’s History of Shaping the Science

When reading about soda and health, it is worth knowing that the sugar industry has a documented history of funding and influencing research to protect its products. Internal documents from the Sugar Research Foundation revealed that the industry funded a literature review published in the New England Journal of Medicine in 1967 that downplayed the link between sugar and heart disease while casting blame on dietary fat. The industry’s funding and involvement were not disclosed.²⁷ The same foundation influenced the National Institute of Dental Research’s approach to tooth decay in the 1970s, steering research away from sugar restriction and toward other interventions like fluoride treatments.²⁸

None of this means the current science on soda and cancer is corrupted, but it provides context for why public understanding of sugar’s health effects has lagged behind what the evidence shows. The beverage industry continues to fund nutrition research, and studies funded by industry tend to produce more favorable results for the sponsor’s product. Independent research has increasingly converged on the view that high sugar-sweetened beverage intake is genuinely harmful across multiple disease categories.

Who Gets Marketed to the Hardest

Soda consumption is not evenly distributed across the population, and neither is the marketing. Research across U.S. media markets found that children and adolescents in areas with higher proportions of Black residents and lower-income households were exposed to significantly more food and beverage advertising, with sugar-sweetened beverages and fast food being the most heavily advertised categories.²⁹ Street-level advertising data from New York City confirmed the pattern: sugary drink ad density was higher in neighborhoods with larger Black populations and higher poverty rates.³⁰

This matters for cancer risk because the communities receiving the most aggressive soda marketing are often the same communities with less access to preventive healthcare, higher rates of obesity and diabetes, and worse cancer outcomes. The soda-cancer link does not exist in a vacuum. It intersects with broader patterns of health inequality, making it a public health concern that goes well beyond individual beverage choices.