Table 3.
Absolute concentrations (95% confidence intervals) and percent change in the absolute concentrations of in insulin-related/IGF signaling biomarkers in quintiles of total dairy and specific dairy foods among 35,352 postmenopausal women in Women’s Health Initiativea,b
| Insulin response biomarkersh | Total dairy quintilesc | % Diffd | F DRe- P-trend | Low-fat dairy quintilesf | % Diffe | FDR P-trend | Full-fat dairy quintilesg | % Diffe | FDR P-trend | |||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Quintile 1 0.0–0.4 servings |
Quintile 5 2.6–15.6 servings |
Quintile 1 0.0–0.1 servings |
Quintile 5 0.8–6.3 servings |
Quintile 1 0.0–0.1 servings |
Quintile 5 2.2–15.4 servings |
|||||||
| Glucose, mg/dL (n=21,677) | 97.5 (96.4, 98.6) | 96.1 (95.0, 97.2) | −1.4 | 3.4E-04 | 97.5 (96.4, 98.7) | 95.6 (94.5, 96.8) | −2.0 | 1.8E-07 | 97.0 (95.9, 98.1) | 96.3 (95.2, 97.4) | −0.7 | 0.06 |
| Insulin, ulU/mL (n=23,763) | 9.3 (8.9, 9.7) | 8.9 (8.5, 9.3) | −4.8 | 2.6E-05 | 9.4 (9.0, 9.8) | 8.6 (8.2, 9.0) | −8.5 | 3.8E-14 | 8.9 (8.6, 9.3) | 8.9 (8.6, 9.4) | −0.1 | 0.07 |
| C-peptide, ng/mL (n=943) | 1.5 (1.2, 1.9) | 1.5 (1.2, 1.9) | 1.6 | 0.99 | 1.5 (1.2, 1.9) | 1.5 (1.2, 1.9) | −2.7 | 0.26 | 1.5 (1.2, 1.8) | 1.6 (1.2, 1.9) | 4.9 | 0.83 |
| IGF-1i, ng/mL (n=3,042) | 85.1 (73.0, 99.2) | 87.7 (75.4, 102.1) | 3.1 | 0.56 | 85.1 (73.2, 99.0) | 90.3 (77.5, 105.3) | 6.0 | 0.15 | 88.4 (75.8, 102.9) | 86.6 (74.5, 100.7) | −2.0 | 0.94 |
| IGFBP-1j, ng/mL (n=979) | 19.7 (13.5, 28.6) | 19.8 (13.7, 28.6) | 0.7 | 0.88 | 19.1 (13.3, 27.5) | 20.7 (14.2, 30.2) | 8.3 | 0.06 | 21.7 (15.0, 31.5) | 18.7 (13.0, 27.0) | −15.0 | 0.36 |
| IGFBP-3, ng/mL (n=2,627) | 3893 (3338, 4541) | 3998 (3431, 4659) | 2.7 | 0.99 | 3915 (3360, 4563) | 4057 (3481, 4729) | 3.6 | 0.40 | 3869 (3317, 4513) | 4008 (3441, 4669) | 3.5 | 0.94 |
| IGFBP-4, ng/mL (n=355) | 467 (372, 585) | 490 (390, 617) | 4.9 | 0.97 | 461 (370, 575) | 511 (412, 633) | 10.2 | 0.76 | 503 (402, 629) | 496 (396, 622) | −1.3 | 0.99 |
| free IGF-1, ng/mL (n=2,203) | 0.76 (0.59, 0.97) | 0.78 (0.61, 1.00) | 3.0 | 0.54 | 0.73 (0.57, 0.93) | 0.66 (0.52, 0.84) | −10.1 | 0.03 | 0.67 (0.52, 0.85) | 0.79 (0.62, 1.00) | 16.2 | 0.16 |
| Insulin response biomarkersh | Total cheese quintilesk | % diff | FDR P-trend | Low-fat cheese quintilesl | % diff | FDR P-trend | Full-fat cheese quintilesm | % diff | FDR P-trend | |||
| Quintile 1 0.0–0.3 servings |
Quintile 5 2.3–12.9 servings |
Quintile 1 0.0 serving |
Quintile 5 0.3–3.2 servings |
Quintile 1 0.0–0.1 servings |
Quintile 5 2.1–11.4 servings |
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| Glucose, mg/dL (n=21,677) | 96.9 (95.8, 98.0) | 96.3 (95.2, 97.4) | −0.6 | 0.02 | 97.0 (96.0, 98.1) | 96.6 (95.5, 97.8) | −0.4 | 0.29 | 96.9 (95.8, 98.0) | 96.2 (95.1, 97.3) | −0.8 | 0.03 |
| Insulin, uIU/mL (n=23,763) | 9.1 (8.7, 9.6) | 8.9 (8.6, 9.3) | −2.3 | 0.02 | 9.2 (8.9, 9.7) | 8.8 (8.4, 9.3) | −4.5 | 3.6E-06 | 9.0 (8.6, 9.4) | 8.9 (8.6, 9.4) | −0.4 | 0.09 |
| C-peptide, ng/mL (n=943) | 1.5 (1.2, 1.9) | 1.5 (1.2, 1.9) | −0.2 | 0.94 | 1.5 (1.2, 1.9) | 1.5 (1.2, 1.9) | −4.0 | 0.48 | 1.5 (1.2, 1.8) | 1.6 (1.2, 1.9) | 4.8 | 0.89 |
| IGF-1i, ng/mL (n=3,042) | 87.0 (74.7, 101.4) | 87.0 (74.9, 101.2) | −0.02 | 0.76 | 85.8 (73.8, 99.6) | 87.9 (75.4, 102.5) | 2.5 | 0.72 | 88.9 (76.3, 103.6) | 86.2 (74.2, 100.2) | −3.1 | 0.84 |
| IGFBP-1j, ng/mL (n=979) | 20.1 (13.9, 29.2) | 19.4 (13.4, 28.0) | −3.9 | 0.65 | 19.0 (13.1, 27.5) | 22.1 (15.2, 32.1) | 15.1 | 0.01 | 21.5 (14.9, 31.2) | 18.6 (12.9, 26.8) | −14.9 | 0.37 |
| IGFBP-3, ng/mL (n=2,627) | 3886 (3333, 4531) | 4002 (3435, 4661) | 2.9 | 0.99 | 3948 (3386, 4602) | 4078 (3496, 4758) | 3.2 | 0.51 | 3867 (3315, 4511) | 4007 (3440, 4668) | 3.6 | 0.94 |
| IGFBP-4, ng/mL (n=355) | 497 (399, 619) | 479 (383, 600) | −3.7 | 0.99 | 499 (401, 621) | 496 (396, 622) | −0.6 | 0.99 | 494 (395, 617) | 493 (394, 617) | −0.1 | 0.99 |
| free IGF-1, ng/mL (n=2,203) | 0.67 (0.52, 0.85) | 0.78 (0.61, 0.99) | 14.8 | 0.24 | 0.74 (0.58, 0.94) | 0.71 (0.56, 0.91) | −3.8 | 0.76 | 0.67 (0.52, 0.85) | 0.79 (0.62, 1.00) | 16.5 | 0.21 |
| Insulin response biomarkersh | Total milk quintilesn | % diff | FDR P-trend | Total yogurt quintileso | % diff | FDR P-trend | Total butter quintilesp,q | % diff | FDR P-trend | |||
| Quintile 1 0.0 serving |
Quintile 5 1.0–18.0 servings |
Quintile 1 0.0 serving |
Quintile 5 0.3–4.0 servings |
Quintile 1 0.0 serving |
Quintile 5 0.5–9.0 servings |
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| Glucose, mg/dL (n=21,677) | 96.8 (95.8, 97.9) | 96.9 (95.8, 98.0) | 0.06 | 0.94 | 97.3 (96.2, 98.4) | 95.9 (94.8, 97.1) | −1.4 | 2.6E-06 | 96.9 (95.9, 98.0) | 97.1 (95.9, 98.2) | 0.2 | 0.42 |
| Insulin, uIU/mL (n=23,763) | 9.1 (8.7, 9.5) | 9.2 (8.8, 9.6) ** | 0.7 | 0.94 | 9.4 (9.0, 9.8) | 8.7 (8.3, 9.1) | −7.6 | 2.4E-12 | 9.1 (8.8, 9.5) | 9.5 (9.1,9.9) | 3.9 | 0.003 |
| C-peptide, ng/mL (n=943) | 1.5 (1.2, 1.9) | 1.5 (1.2, 1.9) | −0.1 | 0.99 | 1.5 (1.2, 1.9) | 1.4 (1.1, 1.8) | −5.6 | 0.27 | 1.5 (1.2, 1.8) | 1.5 (1.2, 1.9) | 3.2 | 0.99 |
| IGF-1i, ng/mL (n=3,042) | 86.9 (74.8, 100.9) | 92.0 (79.0, 107.1) | 5.7 | 0.02 | 85.5 (73.6, 99.3) | 89.1 (76.5, 103.7) | 4.1 | 0.94 | 87.4 (75.4, 101.4) | 82.4 (70.7, 96.0) | −5.9 | 0.11 |
| IGFBP-1j, ng/mL (n=979) | 18.7 (12.9, 27.0) | 18.8 (13.0, 27.2) | 0.8 | 0.95 | 18.7 (13.0, 26.9) | 20.8 (14.4, 30.1) | 10.4 | 0.33 | 20.6 (14.3, 9.5) | 18.7 (12.9, 27.0) | −9.7 | 0.24 |
| IGFBP-3, ng/mL (n=2,627) | 3914 (3362, 4556) | 4095 (3512, 4774) | 4.5 | 0.37 | 3925 (3373, 4568) | 4042 (3469, 4711) | 2.9 | 0.94 | 4020 (3457, 4674) | 3845 (3296, 4484) | −4.4 | 0.35 |
| IGFBP-4, ng/mL (n=355) | 507 (410, 627) | 470 (375, 589) | −7.6 | 0.64 | 501 (406, 619) | 528 (423, 660) | 5.2 | 0.84 | 506 (413, 620) | 474 (381, 591) | −6.5 | 0.90 |
| free IGF-1, ng/mL (n=2,203) | 0.73 (0.67, 0.92) | 0.72 (0.56, 0.91) | −1.4 | 0.95 | 0.74 (0.58, 0.93) | 0.69 (0.54, 0.88) | −6.0 | 0.03 | 0.71 (0.56, 0.90) | 0.80 (0.62, 1.02) | 11.4 | 0.35 |
Values are absolute back-transformed biomarker concentrations since values were natural log-transformed prior to analysis and the bolded numbers represent statistically significant findings (i.e., FDR p value <0.05).
Models were adjusted for age, total energy intake, physical activity, body mass index, smoking, total alcohol, nutritional supplements, non-steroidal anti-inflammatory drug (NSAID), statins, fasting status, education level, race/ethnicity, and case-control status.
Total dairy was calculated as the sum of daily servings of low-fat and full-fat dairy.
Percent differences are the difference between highest quintiles (Q5) and the lowest quintile (Q1) in biomarker concentration. For total yogurt and butter, the lowest quintile included participants in both quintiles 1 and 2 because of zero intake in quintile 1.
FDR: false discovery rate
Low-fat dairy foods included low-fat milk (non-fat, skimmed, 1–2% fat milk), part-skim or reduced-fat cheese, low-fat cottage cheese, low-fat or non-fat frozen desserts, low-fat or non-fat yogurt, other yogurt, and low-fat pizza 12.
Full-fat dairy foods included evaporated or whole milk, condensed milk on cereal, cottage and ricotta cheese, other cheese (cheddar/swiss/cream cheese), ice cream, milk/cream/creamer in coffee or tea, and pizza.
Conversion to SI units: for blood glucose, to convert to mmol/L, multiply by 0.0555; for C-peptide, to convert to nmol/L, multiply by 0.331; for insulin, to convert to mIU/L, multiply by 1; for IGF-1, IGFBP-1, IGFBP-4 and free IGF-1, to convert to nmol/L, multiply by 0.131.
Insulin-like growth factor (IGF)-1.
Insulin-like growth factor binding protein (IGFBP)-1/3/4.
Total cheese was calculated as the sum of daily servings of low-fat cheese and full-fat cheese.
Low-fat cheese included part-skim or reduced-fat cheese such as Mexican type cheeses or mozzarella, low-fat cottage cheese and low-fat pizza.
Full-fat cheese included cottage and ricotta cheese, and other cheese (cheddar/swiss/cream cheese).
Total milk was calculated as the sum of whole milk and low-fat milk.
Total yogurt included non-fat yogurt and all other yogurt.
Butter included butter added to cooked cereal or grits, butter on bread or tortillas, and butter added as fats during cooking.
Servings/day of dairy products were defined as: 8-oz glass skimmed or low-fat milk, 1/2 cup sherbet or ice milk, 1 cup yogurt; 8-oz glass whole milk or cream, 1 tablespoon sour cream, 1/2 cup ice cream, 2 slices of 16” pizza, 1 oz cream cheese, 1 oz or 1 slice other cheese.