Sarcopenia has emerged as a critical geriatric syndrome with profound implications for morbidity, disability, poor quality of life, and even mortality in aging populations (1, 2). The concept of sarcopenia was first introduced by Rosenberg in the late 1990s, emphasizing the age-related loss of muscle mass as a distinct geriatric concern (3). Subsequent landmark epidemiologic research by Baumgartner et al. provided the first operational definition and prevalence estimates using appendicular skeletal muscle mass (ASM) adjusted for height, establishing sarcopenia as a measurable public health issue (4). The European Working Group on Sarcopenia in Older People (EWGSOP) has refined its diagnostic criteria over the past decade, emphasizing low muscle strength as a primary indicator, with low muscle quantity/quality and impaired physical performance further confirming the diagnosis (5). Globally, it affects approximately 10–16% of older adults (6). In China, the prevalence ranges from 14 to 20% among older adults (7–10). With global populations aging rapidly, early identification of modifiable factors, particularly nutritional interventions, is imperative.

Accumulating evidence highlights nutrition as a cornerstone in mitigating sarcopenia progression (11, 12). Nutritional intervention studies demonstrated that high protein oral nutritional supplements might be effective for certain sarcopenia-related outcomes (13, 14), prompting the integration of increasing protein intake into sarcopenia management guidelines (15, 16). Besides, essential amino acids (e.g., leucine), and micronutrients (e.g., vitamin D, antioxidants) are critical for maintaining muscle protein synthesis and reducing oxidative stress, a key driver of muscle atrophy (11, 17–21). However, recent research has shifted toward evaluating whole foods and dietary patterns rather than isolated nutrients, recognizing synergistic effects of bioactive compounds in natural food matrices (22).

Watermelon (Citrullus lanatus), a widely consumed fruit globally, is uniquely positioned as a functional food for sarcopenia prevention due to its high content of L-citrulline, lycopene, β-carotene, and vitamins A and C (23, 24). L-citrulline, a non-essential amino acid, serves as a precursor to L-arginine, enhancing nitric oxide (NO) synthesis, a vasodilator that improves blood flow to skeletal muscles and potentiates nutrient delivery (25). Moreover, watermelon’s antioxidant profile is notable. Lycopene, a potent carotenoid, mitigates oxidative stress by scavenging free radicals, thereby preserving mitochondrial function in muscle cells (26). β-carotene and vitamin C further synergize to reduce inflammatory markers such as interleukin-6 (IL-6) and C-reactive protein (CRP), which are implicated in muscle wasting (27). Intervention and observational studies support these mechanistic pathways in human populations. Randomized controlled trials (RCTs) have shown that L-citrulline supplementation improves muscle protein synthesis and increases lean mass in older adults, enhancing exercise performance and recovery (28, 29); F (30). Watermelon juice consumption has been reported to reduce post-exercise muscle soreness (31). In parallel, the Framingham Offspring Study demonstrated that higher carotenoid intake, including lycopene, was associated with increase in handgrip strength (HGS) and faster gait speed in this cohort of adults (27). Meta-analytic evidence confirms that diets rich in antioxidant-containing fruits are linked to about 40% lower sarcopenia risk in older adults (22). Previous evidence indicates that other fruits rich in L-citrulline and lycopene may also contribute to muscle health in older adults. Higher tomato and tomato product consumption has been associated with reduced decline in HGS and may improve muscle fiber composition and mitochondrial function through pathways such as Adenosine 5′-monophosphate activated protein kinase (AMPK) and Sirtuin 1 activation (26, 32, 33). Similarly, citrus flavonoids like tangeretin and naringin have been shown to enhance skeletal muscle mitochondrial biogenesis and promote oxidative muscle fiber remodeling via AMPK-Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) signaling (34–36). These findings suggest that fruits containing these bioactive compounds might play a protective role against sarcopenia, providing a broader nutritional context for examining the potential benefits of watermelon, which is particularly abundant in both L-citrulline and lycopene.

Despite the biological plausibility and existing preclinical evidence suggesting the beneficial effects of watermelon or its constituents on muscle health, epidemiological data exploring the relationship between watermelon consumption and sarcopenia are scarce. Most existing studies have either focused on specific nutrients or broadly categorized fruits and vegetables without examining watermelon consumption explicitly (11, 13, 14, 17–22). Sarcopenia poses a particularly urgent challenge in China, where rapid demographic aging is occurring alongside significant shifts in dietary patterns (1). By 2040, China is projected to have over 400 million people aged 60 years and older, the largest elderly population in the world (37). Traditional diets are transitioning toward more varied but often lower fruit intake, potentially affecting sarcopenia-related risk factors (38). Understanding diet-health relationships in this context is crucial for developing culturally tailored prevention strategies. Therefore, the present study aims to explore the relationship between watermelon consumption and sarcopenia among elderly participants in the general population of Tianjin, China. We hypothesized that higher watermelon consumption would be inversely associated with sarcopenia prevalence in elderly adults, based on the biological mechanisms of L-citrulline in supporting muscle protein synthesis and the antioxidant properties of watermelon’s bioactive compounds in preserving muscle health.

Our study demonstrates a significant inverse association between watermelon consumption and sarcopenia prevalence in an elderly Chinese population from the TCLSIH cohort. After adjusting for multiple confounding factors, participants with higher watermelon consumption showed substantially lower odds of sarcopenia compared to those with lower consumption. While the association was generally consistent across most population subgroups, individuals with hyperlipidemia showed no significant protective benefit, suggesting that lipid metabolism status might modify watermelon’s beneficial effects on sarcopenia risk.

In this cohort, the average weekly watermelon consumption was quantified as 300 g for males and 250 g for females. Participants consuming watermelon “≤1 time/week” had an estimated weekly intake of approximately 250–300 grams, while those consuming “≥2–3 times/week” had an estimated weekly intake of 500–900 grams. According to the fully adjusted analysis, even modest watermelon consumption (250–300 g/week) was associated with 28% lower odds of sarcopenia, while moderate consumption (500–900 g/week) was associated with 51% lower odds. This dose–response relationship suggests that the L-citrulline content in these consumption amounts, approximately 0.4–0.7 grams for low consumption and 0.8–3.15 grams for moderate consumption based on watermelon’s L-citrulline content of 1.6–3.5 grams per kilogram, might be sufficient to exert meaningful biological effects on muscle health (23, 52).

While no previous studies have specifically examined watermelon consumption in relation to sarcopenia, several investigations have explored the relationship between fruit consumption or specific nutrients abundant in watermelon and muscle health outcomes. A recent meta-analysis reported that antioxidant-rich fruits and vegetables are linked to a 30–40% risk reduction (22), which is comparable in magnitude to our estimates for higher watermelon consumption. Figueroa et al. (29) demonstrated that L-citrulline supplementation (10 g/day) combined with resistance training significantly improved leg lean mass and muscle strength in hypertensive postmenopausal women. Similarly, Wen et al. showed that lycopene supplementation increased the proportion of slow-twitch muscle fibers through AMPK signaling pathway activation, enhancing muscle anti-fatigue capacity in animal models (33). Prospective data from the Framingham Offspring Study showed that higher total carotenoid intake was associated with reduced decline in HGS and gait speed, phenotypes integral to sarcopenia definitions and consistent with our findings (27). However, our study provides important complementary evidence by examining whole food consumption rather than isolated nutrient supplementation. Watermelon provides L-citrulline alongside other potentially beneficial nutrients including lycopene, β-carotene, and vitamin C (23, 24, 53), which may work synergistically to support muscle health through multiple pathways including enhanced NO synthesis, reduced oxidative stress, and improved protein synthesis. This whole-food approach may be more practical and sustainable for population-level sarcopenia prevention compared to isolated supplement interventions.

Several potential biological mechanisms may explain the inverse association between watermelon consumption and sarcopenia observed in our study. First, L-citrulline functions as a precursor to L-arginine, which is subsequently converted to NO (54, 55). L-citrulline supplementation represents a more efficient method for elevating plasma L-arginine levels compared to direct L-arginine supplementation (56). This enhanced conversion improves NO bioavailability in muscle tissues (56). NO acts as a vasodilator through cyclic guanosine monophosphate (cGMP)-mediated phosphorylation (57). This vasodilatory action improves nutrient and oxygen delivery to active muscle tissues (58). Enhanced delivery supports adenosine triphosphate (ATP) and phosphocreatine resynthesis during physical exertion (58). These physiological effects may help sustain muscle force production during repeated contractions. Beyond enhancing circulatory dynamics, NO may improve muscle function through additional mechanisms, including facilitation of ATP hydrolysis and reduction in the metabolic cost of force production (59).

Furthermore, NO bioavailability might be augmented through a nitric oxide synthase (NOS)-dependent L-arginine-NO pathway, with L-citrulline and dietary nitrates serving as critical precursors (60). Recent findings by Sureda et al. (61) have demonstrated that L-citrulline supplementation increases nitrogen availability, which consequently supports protein synthesis in muscle tissue. Complementary evidence from animal models strengthens these observations; notably, in aged rats, a one-week diet enriched with L-citrulline (5 g/kg per day) significantly enhanced absolute muscle protein synthesis rates and increased protein mass (62). Therefore, L-citrulline, as a precursor to NO, may improve muscle function through multiple pathways: enhancing nutrient delivery, reducing ATP utilization costs, and promoting muscle protein synthesis. Further investigations are warranted to elucidate the precise mechanisms underlying the relationship between watermelon consumption and sarcopenia prevention in elderly populations.

Our stratified analyses demonstrated that watermelon’s protective association against sarcopenia remained consistent across most subgroups, except among individuals with hyperlipidemia, suggesting dyslipidemia may nullify watermelon’s protective effects. This finding might be explained by dyslipidemia’s overwhelming catabolic metabolic environment. Dyslipidemia represents a systemic metabolic disorder characterized by heightened oxidative stress, chronic inflammation, and endothelial dysfunction (63). Oxidized low density lipoprotein triggers inflammatory cascades and reactive oxygen species production, creating a pro-inflammatory state that independently promotes sarcopenia pathogenesis (64). In normolipidemic individuals, baseline inflammation and oxidative stress levels are relatively low, allowing watermelon’s antioxidant, anti-inflammatory, and vasodilatory benefits to meaningfully counteract age-related muscle decline. However, in dyslipidemic individuals, pathologically elevated systemic inflammation, oxidative stress, and endothelial dysfunction create a different scenario (63, 65). The endothelial dysfunction characteristic of dyslipidemia directly impairs NO bioavailability, counteracting the mechanism by which watermelon’s L-citrulline provides benefits (65). The magnitude of pro-catabolic stimuli from dyslipidemia likely overwhelms watermelon’s modest protective effects, diminishing its impact to non-significance against this pathological backdrop. Furthermore, statins, common lipid-lowering medications, may cause muscle damage and muscle atrophy through mechanisms involving effects on mitochondrial function, muscle energy metabolism, and protein degradation (66–68). These findings suggest that lipid metabolism status might modify watermelon’s beneficial effects, though underlying mechanisms require further investigation.

In addition to the biological plausibility, the observed association carries clinical and public health relevance. A 28–51% reduction in the odds of sarcopenia is comparable to many established lifestyle interventions, such as consumption of protein, fruit and vegetable or PA, which often yield about 40% risk reductions (22, 69, 70). Given the prevalence of sarcopenia in 14–20% of Chinese older adults (7–10), even modest relative reductions might translate into substantial population-level benefits. In our study population with a 12.6% prevalence, regular watermelon consumption (≥2–3 times/week) might theoretically prevent approximately 6–7 cases per 100 elderly individuals, underscoring its potential as a simple, accessible, and affordable dietary strategy for sarcopenia prevention. Besides, our findings suggested that the effectiveness of watermelon consumption may be context-dependent and influenced by underlying metabolic conditions. Healthcare providers should consider patients’ lipid profiles when recommending dietary strategies for sarcopenia prevention, as individuals with dyslipidemia may require more intensive interventions or adjunctive lipid management to realize the benefits of functional foods.

The main strength of our study is the large sample size, extensive information on other lifestyle factors, and use of a validated FFQ for assessment of dietary consumption. Additionally, when we adjusted for a multitude of potential confounders the results did not change materially, indicating the robustness of our findings. What’s more, the definition of sarcopenia in this study is strictly based on the criterion of AWGS2019, which is more adaptable to the sample population in our study, and may reduce the bias of misclassification to a certain extent. This study also has several limitations. First, self-reported watermelon information is subject to measurement errors. In view of this situation, unreliable FFQs were excluded in our study. Second, muscle mass was measured by bioelectrical impedance analysis rather than the gold standard test dual-energy X-ray absorptiometry. However, results of muscle mass estimation using bioelectrical impedance analysis are highly correlated with that measured using dual-energy X-ray absorptiometry (71). Third, as with any epidemiological study, we cannot completely rule out the possibility of residual or unmeasured confounding. Several important factors were not captured in our analysis, including consumption of other bioactive-rich foods, use of medications that may affect muscle metabolism (including statins, corticosteroids, or angiotensin-converting enzyme inhibitors), and indicators of physical frailty or functional status beyond our measured parameters. Fourth, the cross-sectional design inherently limits causal inference, as we cannot establish temporal relationships between watermelon consumption and sarcopenia development. It remains possible that individuals with better muscle health are more likely to maintain healthier dietary patterns, including higher fruit consumption, creating potential reverse causation bias (72). Fifth, while PA was quantified using validated METs from the IPAQ, our assessment lacked specificity regarding the type of exercise performed. Resistance training and aerobic exercise have differential impacts on muscle mass preservation, with resistance exercise being particularly beneficial for maintaining and building skeletal muscle mass (73). The inability to distinguish between these exercise modalities may have introduced residual confounding, as individuals with higher watermelon consumption might also engage in more beneficial exercise patterns for muscle health. Last, generalizing our results to other populations requires caution due to variations in dietary patterns, genetic polymorphisms, baseline nutritional status, and chronic disease management across populations. Dietary habits and food preparation methods vary substantially across cultures. Western populations typically consume different fruit varieties, portion sizes, and processing methods compared to Chinese populations, which might affect the bioavailability of L-citrulline and other bioactive compounds found in watermelon (74). Genetic polymorphisms affecting NO metabolism, particularly variants in NOS genes, show significant ethnic variation and may influence individual responses to L-citrulline intake (75). Baseline nutritional status varies across different populations, which may modulate the relationship between watermelon consumption and muscle health outcomes (76). Additionally, while our primary analysis showed consistent associations, the limited significant interactions in stratified analyses suggest that the relationship may vary across certain population subgroups, which warrants careful consideration when generalizing findings.

In conclusion, our study provides novel evidence of an inverse association between watermelon consumption and sarcopenia prevalence in an elderly Chinese population. The rich nutrient profile of watermelon, including L-citrulline, offers biologically plausible mechanisms for this relationship. Future research should include well-designed RCTs to verify causality, such as L-citrulline supplementation or controlled watermelon intake in elderly individuals with sarcopenia or pre-sarcopenia. Dose–response RCTs comparing varying watermelon consumption levels could identify optimal intake. Long-term prospective cohorts in different ethnic and geographic populations would clarify temporal relationships and generalizability. Mechanistic studies examining changes in muscle protein synthesis, NO metabolism, and inflammation biomarkers will help elucidate underlying pathways. If confirmed, increasing watermelon consumption might represent a simple, accessible dietary strategy to help combat the growing public health challenge of sarcopenia in aging populations worldwide.