Table 2.
Predictors of nitrate intake by source.
| Plant-sourced nitrate | Animal-sourced nitrate | Water-sourced nitrate | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Model 1 | Model 2 | Model 1 | Model 2 | Model 1 | Model 2 | ||||||||
| n | β (95% CI) | p-val. | β (95% CI) | p-val. | β (95% CI) | p-val. | β (95% CI) | p-val. | β (95% CI) | p-val. | β (95% CI) | p-val. | |
| Age (years) | |||||||||||||
| 50–54 | 23,543 | ref. | ref. | ref. | ref. | ref. | ref. | ||||||
| 55–60 | 20,241 | −0.70 (−1.11, −0.30) | <0.001 | −0.29 (−0.66, 0.08) | 0.127 | 0.15 (0.08, 0.23) | <0.001 | 0.24 (0.17, 0.30) | <0.001 | −0.15 (−0.28, −0.02) | 0.028 | −0.14 (−0.27, −0.01) | 0.041 |
| 61–65 | 11,970 | −1.43 (−1.90, −0.95) | <0.001 | −1.29 (−1.72, −0.85) | <0.001 | 0.25 (0.16, 0.34) | <0.001 | 0.28 (0.20, 0.36) | <0.001 | −0.41 (−0.56, −0.26) | <0.001 | −0.41 (−0.56, −0.25) | <0.001 |
| Sex | |||||||||||||
| Female | 29,178 | ref. | ref. | ref. | ref. | ref. | ref. | ||||||
| Male | 26,576 | −2.24 (−2.63, −1.86) | <0.001 | −10.02 (−10.40, −9.64) | <0.001 | 0.67 (0.60, 0.74) | <0.001 | −0.84 (−0.91, −0.77) | <0.001 | −0.65 (−0.77, −0.52) | <0.001 | −0.84 (−0.98, −0.71) | <0.001 |
| BMI (kg/m2) | |||||||||||||
| Underweight (BMI <18.5) | 435 | 1.51 (−0.53, 3.55) | 0.145 | 0.25 (−1.61,2.11) | 0.791 | 0.28 (−0.09, 0.65) | 0.134 | 0.04 (−0.30, 0.36) | 0.841 | −0.41 (−1.07, 0.25) | 0.220 | −0.44 (−1.10, 0.21) | 0.188 |
| Normal weight (BMI 18.5–24.9) | 24,006 | ref. | ref. | ref. | ref. | ref. | ref. | ||||||
| Overweight (BMI 25.0–29.9) | 23,231 | −1.54 (−1.94, −1.15) | <0.001 | −0.93 (−1.29, −0.57) | <0.001 | 0.08 (0.00, 0.15) | 0.037 | 0.20 (0.13, 0.26) | <0.001 | 0.10 (−0.03,0.22) | 0.144 | 0.11 (−0.02,0.24) | 0.091 |
| Obese (BMI ≥30) | 8,082 | −3.15 (−3.70, −2.59) | <0.001 | −2.62 (−3.13, −2.12) | <0.001 | 0.20 (0.10, 0.30) | <0.001 | 0.30 (0.21, 0.39) | <0.001 | 0.27 (0.09, 0.45) | 0.003 | 0.28 (0.11, 0.46) | 0.002 |
| Physical activity level (MET score) | |||||||||||||
| ≤43.50 | 18,889 | ref. | ref. | ref. | ref. | ref. | ref. | ||||||
| 43.75–73.50 | 18,481 | 4.01 (3.58, 4.45) | <0.001 | 2.55 (2.15, 2.95) | <0.001 | 0.31 (0.23, 0.39) | <0.001 | 0.03 (−0.05, 0.10) | 0.477 | 0.04 (−0.10, 0.18) | 0.584 | 0.00 (−0.14, 0.14) | 0.954 |
| ≥73.75 | 18,384 | 7.39 (6.95, 7.83) | <0.001 | 4.07 (3.66, 4.47) | <0.001 | 0.69 (0.62, 0.77) | <0.001 | 0.05 (−0.03, 0.12) | 0.216 | 0.25 (0.11,0.39) | <0.001 | 0.17 (0.02, 0.31) | 0.021 |
| Alcohol intake (units/day)* | |||||||||||||
| Abstainer | 1,291 | −0.30 (−1.50, 0.91) | 0.630 | −0.25 (−1.35, 0.84) | 0.652 | 0.02 (−0.20, 0.24) | 0.842 | 0.03 (−0.17, 0.22) | 0.791 | 0.36 (−0.02, 0.75) | 0.065 | 0.37 (−0.02, 0.75) | 0.064 |
| >0–1 | 24,700 | ref. | ref. | ref. | ref. | ref. | ref. | ||||||
| >1–2 | 13,217 | 0.54 (0.08, 1.01) | 0.021 | −0.33 (−0.75, 0.09) | 0.126 | 0.12 (0.04, 0.20) | 0.005 | −0.05 (−0.12, 0.03) | 0.194 | −0.08 (−0.23,0.07) | 0.270 | −0.10 (−0.25,0.04) | 0.168 |
| >2 | 16,546 | −0.85 (−1.30, −0.40) | <0.001 | −3.93 (−4.34, −3.51) | <0.001 | −0.11 (−0.19, −0.02) | 0.011 | −0.71 (−0.79, −0.64) | <0.001 | −0.51 (−0.66, −0.37) | <0.001 | −0.59 (−0.75, −0.44) | <0.001 |
| Smoking status | |||||||||||||
| Never | 19,563 | ref. | ref. | ref. | ref. | ref. | ref. | ||||||
| Former | 16,056 | 1.00 (0.54, 1.45) | <0.001 | 1.43 (1.02, 1.84) | <0.001 | −0.19 (−0.11, −0.28) | <0.001 | −0.11 (−0.19, −0.04) | 0.002 | 0.22 (0.07, 0.36) | 0.004 | 0.22 (0.08, 0.37) | 0.003 |
| Current | 20,135 | −5.32 (−5.76, −4.89) | <0.001 | −5.08 (−5.47, −4.68) | <0.001 | −0.31 (−0.39, −0.23) | <0.001 | −0.28 (−0.35, −0.21) | <0.001 | 0.60 (0.46, 0.74) | <0.001 | 0.58 (0.44, 0.72) | <0.001 |
| Education level | |||||||||||||
| ≤7 years | 18,354 | ref. | ref. | ref. | ref. | ref. | ref. | ||||||
| 8–10 years | 25,697 | 3.45 (3.06, 3.89) | <0.001 | 3.84 (3.46, 4.22) | <0.001 | 0.06 (−0.01, 0.14) | 0.098 | 0.14 (0.07, 0.20) | <0.001 | −0.45 (−0.59, −0.32) | <0.001 | −0.45 (−0.58, −0.31) | <0.001 |
| ≥11 years | 11,703 | 11.35 (10.83, 11.87) | <0.001 | 10.71 (10.24, 11.18) | <0.001 | 0.57 (0.48, 0.67) | <0.001 | 0.46 (0.38, 0.55) | <0.001 | −0.77 (−0.94, −0.60) | <0.001 | −0.80 (−0.96, −0.63) | <0.001 |
Associations between selected demographic and lifestyle variables and nitrate intake from plant, animal, and water sources. Estimates [β (95% confidence intervals)] and p-values were obtained from separate linear regression models. Model 1 included all predictors of interest; Model 2 included all predictors plus energy intake when plant-sourced and animal-sourced nitrate intakes were the outcomes of interest and water intake when water-sourced nitrate intake was the outcome of interest. MET, metabolic equivalent. *1 unit = 12 g.