TABLE 1.
Baseline age-adjusted characteristics of participants in the Nurses’ Health Study according to quintiles of total protein intake (percent of total energy)
| Quintiles of total protein intake |
|||||
|---|---|---|---|---|---|
| Q1 (n = 9752) | Q2 (n = 9753) | Q3 (n = 9752) | Q4 (n = 9753) | Q5 (n = 9752) | |
| Age (y)1 | 48.3 ± 6.4 | 48.3 ± 6.2 | 48.5 ± 6.2 | 48.8 ± 6.2 | 49.2 ± 6.1 |
| Total protein intake (% of total energy)2 | 14.2 ± 1.3 | 16.5 ± 0.4 | 18.0 ± 0.4 | 19.5 ± 0.5 | 22.5 ± 1.9 |
| Total protein intake (g/d)2 | 57.7 ± 5.7 | 66.9 ± 2.9 | 72.3 ± 2.8 | 78.1 ± 3.2 | 89.2 ± 7.7 |
| Animal protein intake (% of total energy)2 | 9.5 ± 1.5 | 11.6 ± 1.0 | 13.1 ± 1.0 | 14.6 ± 1.0 | 17.7 ± 2.3 |
| Animal protein intake (g/d)2 | 38.6 ± 6.5 | 47.2 ± 4.6 | 52.7 ± 4.5 | 58.5 ± 4.8 | 70.0 ± 8.9 |
| Dairy protein intake (% of total energy)2 | 2.8 ± 1.2 | 3.3 ± 1.4 | 3.6 ± 1.5 | 4.0 ± 1.7 | 4.4 ± 2.1 |
| Dairy protein intake (g/d)2 | 10.9 ± 4.8 | 13.1 ± 5.3 | 14.4 ± 6.0 | 15.8 ± 6.8 | 17.8 ± 8.3 |
| Plant protein intake (% of total energy)2 | 4.7 ± 1.1 | 4.9 ± 0.9 | 4.9 ± 0.9 | 4.9 ± 0.9 | 4.8 ± 1.0 |
| Plant protein intake (g/d)2 | 19.1 ± 4.2 | 19.6 ± 3.6 | 19.6 ± 3.5 | 19.6 ± 3.6 | 19.1 ± 4.0 |
| Race, White (%) | 94.9 | 95.1 | 95.8 | 95.0 | 94.9 |
| Married (%) | 87.4 | 90.1 | 90.6 | 90.1 | 89.1 |
| Education | |||||
| Registered nurse (%) | 76.0 | 72.7 | 70.6 | 68.8 | 67.8 |
| Bachelors (%) | 16.6 | 18.5 | 19.6 | 20.5 | 19.8 |
| Master’s or higher (%) | 7.4 | 8.8 | 9.8 | 10.7 | 12.4 |
| Physical activity (MET-h/wk)2 | 10.6 ± 22.0 | 12.3 ± 19.5 | 12.1 ± 17.7 | 12.8 ± 17.5 | 14.1 ± 21.3 |
| BMI (kg/m2) | |||||
| BMI <25 (%) | 68.7 | 65.9 | 62.0 | 58.8 | 51.9 |
| BMI 25 to <30 (%) | 21.5 | 23.3 | 25.2 | 27 | 29.9 |
| BMI ≥30 (%) | 9.8 | 10.8 | 12.8 | 14.2 | 18.2 |
| Alcohol intake (g/d)2 | 9.6 ± 15.0 | 7.8 ± 11.2 | 6.5 ± 9.4 | 5.6 ± 8.1 | 4.1 ± 6.4 |
| Smoking status | |||||
| Never smoker (%) | 41.8 | 43.2 | 45.1 | 42.8 | 41.2 |
| Past smoker (%) | 29.3 | 33.6 | 33.5 | 36.0 | 39.0 |
| Current smoker (%) | 28.9 | 23.2 | 21.4 | 21.2 | 19.8 |
| Postmenopausal hormone use | |||||
| Premenopausal | 49.3 | 49.5 | 49.2 | 49.4 | 47.7 |
| Never used (%) | 30.3 | 29.8 | 29.7 | 28.7 | 29.4 |
| Former user (%) | 11.5 | 11.8 | 12.3 | 12.7 | 12.7 |
| Current user (%) | 8.9 | 8.9 | 8.8 | 9.2 | 10.2 |
| Current aspirin use (%) | 70.2 | 73.0 | 71.8 | 71.4 | 70.4 |
| Multivitamin use (%) | 32.7 | 34.6 | 36.3 | 38.3 | 39.2 |
| Hypertension (%) | 15.8 | 15.1 | 16.8 | 17.8 | 20.5 |
| High cholesterol (%) | 4.9 | 5.4 | 5.1 | 6.0 | 7.3 |
| Total energy (kcal/d)2 | 1902 ± 531 | 1837 ± 491 | 1769 ± 469 | 1705 ± 451 | 1568 ± 434 |
| Total fat intake (% of total energy)2 | 33.0 ± 5.5 | 34.2 ± 4.9 | 34.3 ± 4.9 | 34.4 ± 5.0 | 34.2 ± 5.6 |
| Total carbohydrate intake (% of total energy)2 | 50.9 ± 7.5 | 48.1 ± 6.4 | 46.9 ± 6.1 | 45.6 ± 6.2 | 43.1 ± 6.8 |
| AHEI2 | 40.8 ± 9.2 | 42.9 ± 8.9 | 44.5 ± 8.9 | 46.3 ± 9.0 | 49.8 ± 9.4 |
| Carbohydrates from whole grains (% of total energy)2 | 2.9 ± 2.9 | 3.3 ± 2.7 | 3.5 ± 2.8 | 3.7 ± 2.9 | 3.7 ± 3.0 |
| Red and processed red meat intake (servings/wk)2 | 7.3 ± 4.1 | 8.0 ± 4.2 | 8.2 ± 4.2 | 8.1 ± 4.4 | 7.6 ± 4.8 |
| Chicken intake (servings/wk)2 | 2.4 ± 1.6 | 3.1 ± 1.8 | 3.5 ± 2.0 | 4.1 ± 2.2 | 5.3 ± 3.5 |
| Fish intake (servings/wk)2 | 1.2 ± 0.8 | 1.6 ± 1.0 | 1.8 ± 1.2 | 2.2 ± 1.4 | 3.1 ± 2.1 |
| Legume intake (servings/wk)2 | 2.5 ± 1.7 | 2.7 ± 1.6 | 2.8 ± 1.7 | 2.8 ± 1.8 | 2.9 ± 2.0 |
| Nut intake (servings/wk)2 | 1.7 ± 2.3 | 1.7 ± 2.2 | 1.6 ± 2.0 | 1.5 ± 2.0 | 1.3 ± 1.8 |
| Egg intake (servings/wk)2 | 2.1 ± 1.7 | 2.3 ± 1.8 | 2.3 ± 1.9 | 2.4 ± 2.0 | 2.5 ± 2.2 |
| Dairy intake (servings/wk)2 | 13.0 ± 8.9 | 14.2 ± 8.4 | 14.6 ± 8.5 | 14.9 ± 8.4 | 14.8 ± 8.7 |
| SSB intake (servings/wk)2 | 4.5 ± 6.1 | 2.2 ± 3.1 | 1.5 ± 2.4 | 1.0 ± 1.8 | 0.6 ± 1.2 |
| Fruit intake (servings/wk) | 9.6 ± 7.5 | 10.2 ± 7.2 | 10.4 ± 6.7 | 10.6 ± 6.9 | 10.7 ± 6.8 |
| Vegetable intake (servings/wk)2 | 17.5 ± 8.3 | 19.4 ± 8.6 | 20.1 ± 8.9 | 21.2 ± 9.2 | 22.4 ± 10.0 |
AHEI, alternative healthy eating index; BMI, body mass index; MET, metabolic equivalent; Q, quintile; SD, standard deviation; SSB, sugar-sweetened beverage.
1
Summary statistics include age-standardized means and SDs for continuous covariates (except for age) and proportions for categorical variables by quintiles of protein intake expressed in percent of total energy intake.
2
Mean, SD (all such values)