Cutting back on sugary drinks may protect men’s fertility, review finds

Emerging evidence links regular sugary drink intake to impaired sperm quality and DNA damage. Find out why experts recommend reducing SSBs for reproductive health.

Recommendations for reducing the impact of SSBs on sperm health.

Research shows that regular consumption of sugar-sweetened beverages (SSB) is associated with adverse effects on male reproductive health, primarily through hormonal imbalances and oxidative damage.

Recently, scientists reviewed the available literature to document existing evidence on the association between SSB consumption and sperm health. This narrative review has been published in the journal Nutrients.

The current review included studies published from 2000 to 2024 and assessed all relevant research identified in a search conducted between 11 October 2024 and 14 December 2024 from multiple databases, including PubMed, ScienceDirect, and Google Scholar. After removing duplicates, eleven observational and cohort studies fulfilled all eligibility criteria and were considered for the present review.

What are sugar-sweetened beverages?

SSBs are the largest source of added sugar in the diet. For instance, a standard 355ml serving of soda contains around 35.0–37.5 g of sugar and 140–150 calories. SSBs typically contain high concentrations of caloric sweeteners, such as high-fructose corn syrup (HFCS), sucrose, or fruit juice concentrates.

An increase in global SSB consumption by almost 23% between 1990 and 2018 has been noted. SSB consumption is higher in men than in women. According to the Health Promotion Board (HPB) in Singapore, an average person consumed around 60 grams of sugar daily in 2018.

Sperm health and sugar-sweetened beverages

Multiple studies have documented a significant decline in sperm health, with average sperm concentrations decreasing by over 50% between 1973 and 2018. Diverse conditions may affect male reproduction, including reduced total sperm count, ejaculated semen volume, sperm motility and viability, and abnormal sperm morphology.

Previous studies have also shown that poor semen quality is associated with long-term morbidity and increases hospitalization risks, specifically for diabetic patients or those with cardiovascular conditions.

Increased SSB consumption leads to obesity, which is a known contributor to reduced sperm quality. In addition, high sugar intake triggers multiple metabolic conditions, such as insulin resistance, elevated triglycerides, and accelerated ageing. Numerous studies have established a dose-response relationship, which suggests that higher SSB intake exacerbates adverse outcomes.

High SSB intake, i.e., regular consumption of more than seven drinks per week, equivalent to 245.0–262.5 grams of sugar, is associated with a significant decline in sperm concentration and motility. Men who consumed more than seven SSBs a week exhibited a reduction in sperm concentration by 22% compared to non-consumers.

Similarly, higher SSB intake was inversely associated with semen volume; compared to non-drinkers, men who drank more than seven SSBs a week generated 6% lower semen volume. However, this reduction in semen volume was not always statistically significant. Previous studies also revealed that higher SSB consumption was negatively associated with sperm motility; however, the impact was found to be relatively modest and not statistically significant. Contradictory findings regarding the association between high SSB intake and a reduction in the percentage of morphologically normal sperm have been documented. Some studies have even reported minimal or positive associations between SSB intake and sperm morphology, indicating inconsistency in the evidence.

Mechanisms by which SSB affects male reproductive health

SSB may cause obesity, which disrupts the hypothalamic-pituitary-gonadal axis, causing impaired gonadotropin responses and altered ultrastructure of ejaculated sperm.

A previous study revealed that high SSB intake reduces hormone levels, including inhibin-B, which is associated with a lower sperm count. Hormonal disruptions through reduced inhibin-B/follicular stimulating hormone (FSH) ratios could be the underlying mechanisms correlating the impact of increased oxidative stress and metabolic dysfunction on sperm health.

SSB induces oxidative stress by generating reactive oxygen species (ROS), which damage DNA and impair sperm’s fertilization capacity. It also damages the sperm membrane through lipid peroxidation and promotes mitochondrial dysfunction, which reduces sperm motility and viability. These damages are typically assessed through molecular assays such as the sperm chromatin structure assay (SCSA), the comet assay (single-cell gel electrophoresis), and TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling).

Chronic oxidative stress also causes accelerated cellular ageing. High sugar-sweetened soda consumption has been associated with shorter leukocyte telomere length in healthy adults, indicating the possible role of SSB in promoting systemic oxidative damage and premature biological aging.

Higher SSB consumption also triggers transient hyperglycemia, elevates ROS production, and affects endothelial function in both microvascular and macrovascular circulations. Antioxidant therapy with N-acetylcysteine and apocynin could alleviate vascular dysfunction. Antioxidant supplementation, such as coenzyme Q10, vitamins C and E, and glutathione, has shown positive effects in mitigating oxidative stress-induced cellular damage. However, the review notes that while supplementation may help in certain cases, excessive use could paradoxically impair sperm function, and a balanced, antioxidant-rich diet is recommended as a safer and more sustainable long-term strategy to improve male reproductive health.

Some included studies also examined artificially sweetened beverages, which generally showed minimal or no effect on sperm health, but further research is needed to clarify these findings.

Conclusions and future outlook

Based on the current body of evidence, regular consumption of SSBs is associated with reductions in sperm count, motility, and increased DNA fragmentation, which may impair male reproductive health and fertility. However, most of the evidence is observational and does not establish direct causality.

A balanced diet rich in antioxidants can help mitigate low sperm count, motility, and volume. Lifestyle modifications and public health measures aimed at reducing SSB consumption, maintaining a healthy BMI, and improving overall metabolic health are recommended as part of a comprehensive approach to supporting male reproductive function.

To validate the current evidence pool, longitudinal studies with standardized study design and methodology for semen analysis are essential. Biomarkers of oxidative stress and detailed dietary assessments could help uncover the underlying mechanism by which SSB intake impacts sperm volume and quality. Considering the global population's diverse nutritional and genetic makeup, it is imperative to conduct similar research on Asian populations. It is also important to account for confounding factors such as BMI, physical activity, dietary antioxidant intake, and environmental exposures in future studies to clarify the true relationship between SSB intake and sperm health.