Table 3.
Weighted linear mixed models evaluating the association between substitution of daily protein intakes for carbohydrate, fat, and other types of protein, assessed up to 4 times per menstrual cycle (menstruation, midfollicular phase, expected ovulation, and midluteal phase) for 2 cycles,a and percent difference in log-transformed serum reproductive hormone concentrations measured up to 8 times per menstrual cycle for 2 cycles
| Carbohydrate Substitution Modelb | Fat Substitution Modelc | Protein Substitution Modeld | ||||
|---|---|---|---|---|---|---|
| Tertile 1 vs Tertile 2 | Tertile 3 vs Tertile 2 | Tertile 1 vs Tertile 2 | Tertile 3 vs Tertile 2 | Tertile 1 vs Tertile 2 | Tertile 3 vs Tertile 2 | |
| % Difference (95% CI) | % Difference (95% CI) | % Difference (95% CI) | % Difference (95% CI) | % Difference (95% CI) | % Difference (95% CI) | |
| Total protein (% energy) | ||||||
| Estradiol (pg/mL) | 0.3 (-4.6,5.5) | 1.7 (-3.4, 7.0) | 0.0 (-4.9, 5.2) | 2.1 (-3.0, 7.6) | – | – |
| Progesterone (ng/mL)e | -4.6 (-18.9, 12.3) | 1.0 (-13.6, 17.9) | -7.0 (-21.2, 9.6) | 2.8 (-12.2, 20.5) | – | – |
| LH (ng/mL) | -1.0 (-6.2, 4.5) | -2.2 (-7.3, 3.2) | -0.7 (-6.0, 4.8) | -2.6 (-7.7, 2.9) | – | – |
| FSH (mIU/mL) | 0.4 (-3.1, 4.1) | -0.5 (-4.0, 3.2) | 0.5 (-3.0, 4.1) | -0.5 (-4.1, 3.2) | – | – |
| Testosterone (ng/dL) | 0.7 (-1.1, 2.6) | -1.5 (-3.4, 0.3) | 0.9 (-1.0, 2.8) | -1.8 (-3.6, 0.1) | – | – |
| SHBG (nmol/L) | -1.8 (-3.5, -0.1) | -1.2 (-3.0, 0.6) | -1.8 (-3.5, -0.1) | -1.2 (-3.0, 0.6) | – | – |
| Animal protein f (%energy) | ||||||
| Estradiol (pg/mL) | -1.0 (-5.9, 4.2) | 1.7 (-3.3, 7.0) | -1.2 (-6.2, 4.0) | 2.1 (-3.0, 7.5) | -0.2 (-5.3,5.2) | 1.7 (-3.6,7.2) |
| Progesterone (ng/mL)f | -2.9 (-17.7, 14.7) | 1.3 (-13.5, 18.5) | -4.2 (-19.2, 13.4) | 3.1 (-12.3, 21.1) | -3.8 (-19,14.4) | 2.0 (-13.8,20.6) |
| LH (ng/mL) | 1.2 (-4.2, 7.0) | 1.8 (-3.6, 7.4) | 1.4 (-4.1, 7.2) | 1.5 (-3.9, 7.2) | 1.5 (-4.1,7.4) | 0.1 (-5.4,6.0) |
| FSH (mIU/mL) | 1.3 (-2.3, 5.0) | 2.3 (-1.3, 6.1) | 1.3 (-2.4, 5.0) | 2.3 (-1.3, 6.1) | 1.4 (-2.3,5.2) | 1.8 (-2.0,5.6) |
| Testosterone (ng/dL) | 0.7 (-1.2, 2.7) | -0.7 (-2.6, 1.1) | 0.8 (-1.1, 2.8) | -0.9 (-2.8, 0.9) | 0.7 (-1.2,2.7) | -0.9 (-2.8,1.0) |
| SHBG (nmol/L) | -0.4 (-2.2, 1.4) | 0.2 (-1.6, 2.0) | -0.4 (-2.2, 1.4) | 0.1 (-1.7, 1.9) | -0.5 (-2.3,1.3) | 0.4 (-1.4,2.3) |
| Vegetable protein g (%energy) | ||||||
| Estradiol (pg/mL) | -0.3 (-5.2, 4.9) | -4.2 (-9.2, 1.0) | -0.4 (-5.3, 4.8) | -4.2 (-9.2, 1.1) | -0.5 (-5.5,4.8) | -4.0 (-9.1,1.4) |
| Progesterone (ng/mL)f | -16.6 (-29.0, -2.0) | 11.4 (-5.6, 31.6) | -17.3 (-29.7, -2.8) | 12.3 (-5.1, 32.7) | -16.5 (-29.2,-1.6) | 13.1 (-4.5,33.8) |
| LH (ng/mL) | 2.9 (-2.5, 8.7) | 0.6 (-4.9, 6.5) | 2.9 (-2.5, 8.7) | 0.7 (-4.9, 6.6) | 2.6 (-2.9,8.5) | -0.1 (-5.7,5.9) |
| FSH (mIU/mL) | 3.8 (0.2, 7.6) | 1.4 (-2.4, 5.4) | 3.8 (0.2, 7.6) | 1.4 (-2.4, 5.4) | 3.9 (0.2,7.7) | 1.5 (-2.4,5.5) |
| Testosterone (ng/dL) | -0.2 (-2.1, 1.6) | 0.7 (-1.2, 2.7) | -0.3 (-2.1, 1.6) | 0.7 (-1.2, 2.7) | 0.1 (-1.7,2.0) | 0.6 (-1.3,2.6) |
| SHBG (nmol/L) | -0.2 (-1.9, 1.6) | 0.0 (-1.8, 1.9) | -0.2 (-1.9, 1.6) | 0.0 (-1.8, 1.9) | -0.3 (-2.1,1.5) | 0.2 (-1.6,2.1) |
All models were adjusted for prior hormone levels using inverse probability weights.
Abbreviations: BMI, body mass index; CI, confidence interval; FSH, follicle-stimulating hormone; LH, luteinizing hormone; SHBG, sex hormone-binding globulin.
a Energy from total protein intake, tertile 1: 3.5%–13.2% of energy; tertile 2: 13.2%–17.4% of energy; tertile 3: 17.4%–41.7% of energy. Energy from animal protein intake, tertile 1: 0.0%–7.5% of energy; tertile 2, 7.5%–12.1% of energy; tertile 3, 12.1%–40.7% of energy. Energy from vegetable protein intake, tertile 1, 0.4T–4.3% of energy; tertile 2, 4.3T–5.9% of energy; tertile 3, 5.9T–19.8% of energy.
b Adjusted for age, race, BMI, physical activity, alcohol, blood cadmium, mercury, and lead concentrations, and fiber, total energy, and fat intakes.
c Adjusted for age, race, BMI, physical activity, alcohol, blood cadmium, mercury, and lead concentrations, and fiber, total energy, and carbohydrate intakes.
d Adjusted for age, race, BMI, physical activity, alcohol, blood cadmium, mercury, and lead concentrations, and fiber, total energy, fat, carbohydrate, and other types of protein intakes (ie, animal protein models were adjusted for vegetable protein and vegetable protein models were adjusted for animal protein).
e Includes only measurements of progesterone during the luteal phase.
f Derived from consumption of red meats (beef, veal, lamb, pork, game, and organ meats), poultry, processed meats (cured pork, cold cuts, and sausage), fish (fish and shellfish), and eggs.
g Derived from consumption of meat alternatives (veggie burgers, tofu, tempeh, textured vegetable protein, and soy nut), legumes (dried beans, mature lima beans, refried beans, and beans in sauce and recipe), nuts and seeds, and nut and seed butters.