Methodological characteristics and hormonal outcomes of human studies evaluating the impact of dietary sugar intake on serum testosterone levels in males.
| Study | Study type | Population | Sugar exposure | Fasting status/Sampling context | Testosterone assay method | Confounder adjustment | Main hormonal finding |
|---|---|---|---|---|---|---|---|
| Acute studies: Single glucose load or short-term postprandial feeding | |||||||
| Iranmanesh et al., 2012 [10] | Acute physiological interventional study | 57 healthy adult men (19–78 years) | 75 g oral glucose load vs. water | Overnight fast; intensive 10-min interval sampling for 6.5 h | Chemiluminescent immunoassay | Multivariate regression for age, BMI, visceral fat, and metabolic hormones | Basal T secretion: 5,256 → 4,608 ng·dL−1·6.5 h−1 (↓12.3%, p < 0.0001). Total T secretion: 6,065 → 5,474 ng·dL−1·6.5 h−1 (↓9.7%, p < 0.001). T concentration slope 5.5× steeper after glucose vs. water (p < 0.001). Pulsatile LH secretion: 20 → 18 IU·L−1·6.5 h−1 (p = 0.043). |
| Gagliano-Jucá et al., 2019 [11] | Acute metabolic intervention | Healthy eugonadal men (aging OGTT cohort + young MMTT cohort) | OGTT and carbohydrate-rich mixed meal | 10–12 h overnight fast; serial early-morning sampling every 20 min | LC-MS/MS | Within-subject paired design (no covariate adjustment required) | ~20–30% transient decline in serum total testosterone within 60–90 min of glucose ingestion. |
| Van de Velde et al., 2020 [6] | Observational postprandial physiology study | 43 adult men across the age/BMI spectrum | Standardized mixed meal tolerance test | ≥ 8 h fast; sampling at baseline, 30, 60, 120 min | LC-MS/MS | Linear mixed-effects modelling including metabolic variables | Mean total T decrease: 13 ± 12% at 30 min; 15 ± 15% at 60 min (p < 0.001 at all timepoints). Free T decrease: 15 ± 13% at 30 min; 17 ± 16% at 60 min. Younger men (≤ 40 years) showed an additional 2.7 nmol/L steeper decline at 60 min vs. older men (p < 0.001). SHBG unchanged. |
| Pearce and Tremellen, 2019 [3] | Dietary metabolic pilot intervention | Overweight/obese men (18–50 years) | Macronutrient feeding protocols, including the refined carbohydrate arm (orange juice) | Overnight fast; baseline and hourly sampling over 5 h | Not explicitly specified in methods | Adjustments for age, BMI, habitual diet, sleep, and activity | Carbohydrates alone (orange juice): no significant change vs. fasting (p = NS). Carbohydrates + PUFA: significantly reduced T vs. fasting (p = 0.040). Mean baseline T: 11.7 ± 3.0 nmol/L. PUFA alone: ↓3.2 nmol/L at 1 h (p = 0.023), persisting to 5 h (p = 0.012). |
| Chronic/Epidemiological studies: habitual dietary patterns or long-term dietary intervention | |||||||
| Chen et al., 2018 [12] | Cross-sectional epidemiological study (NHANES) | 991 US men aged 20–39 years | SSB intake (24-h recall) | Single blood sampling; timing accounted for circadian variation | Electrochemiluminescence immunoassay | Multivariable adjustment (age, BMI, race, lifestyle, socioeconomic factors) | Highest SSB quartile (≥ 442 kcal/day) vs. lowest (≤ 137 kcal/day): aOR for low testosterone = 2.29 (p = 0.041). BMI ≥ 25 kg/m2: aOR = 3.68 (p = 0.044) as an independent risk factor. |
| Nassan et al., 2021 [5] | Cross-sectional fertility cohort study | ~2,935 Danish young men (~18 years) | Soft drink intake via validated FFQ | Morning venous sampling; time-of-day adjustment in models | Time-resolved fluoroimmunoassay/ELISA (platform changed during study) | Extensive adjustment (age, BMI, lifestyle, diet patterns, SES, substance use) | Total testosterone: p-trend = 0.15 (not statistically significant across SSB quartiles). Primary significant effects: sperm concentration –13.0 million/mL in the highest SSB quartile vs. non-consumers (95% CI: –21.0, –5.5; p-trend = 0.001); inhibin-B –12 pg/mL (95% CI: –21, –4). |
| Corsetti et al., 2023 [18] | Prospective dietary lifestyle intervention | 50 subfertile men (35–45 years) | Low-carbohydrate organic Mediterranean diet (3 months) | Post-intervention hormonal assessment; fasting status not clearly specified | Not specified | Minimal reported adjustment | Testosterone: 3.2 ± 0.3 ng/mL → 6.92 ± 1.16 ng/mL (↑116%; p = 0.011; n = 30). Sperm DFI: 44.2 ± 3.02% → 23.2 ± 3.57% (↓47.5%; p = 0.001; n = 20 in low-carb subgroup). |
aOR: adjusted odds ratio; BMI: body mass index; DFI: DNA fragmentation index; ELISA: enzyme-linked immunosorbent assay; FFQ: food frequency questionnaire; LC-MS/MS: liquid chromatography-tandem mass spectrometry; LH: luteinizing hormone; MMTT: mixed meal tolerance test; NHANES: National Health and Nutrition Examination Survey; OGTT: oral glucose tolerance test; PUFA: polyunsaturated fats; SES: socioeconomic status; SHBG: sex hormone binding globulin; SSB: sugar-sweetened beverages.