TABLE 2.
Characteristics of the prospective cohort studies included in the meta-analysis
| Author, year (ref) | Exposure source/percentage of participants using supplements (%) | Categories of intake | Exposure assessment | Adjustment for covariates | Quality score | |||
|---|---|---|---|---|---|---|---|---|
| Al-Delaimy et al., 2004 (51) | Foods + supplements; N.A. (folate) | Folate (μg/d): 30–210, 211–271, 272–354, 355–526, >526 | FFQ, 61 food items | Age, time period, smoking history, BMI, hormone use and menopausal status, currently taking aspirin, vitamin E supplements, physical activity, alcohol use, history of high blood pressure, history of diabetes, history of hypercholesterolemia, parental history of myocardial infarction at or before the age of 65 y, total caloric intake | 8 | |||
| Bazzano et al., 2002 (24) | Foods + supplements; 30% (multivitamin) | Folate (μg/d): <136, 136–203.7, 203.7–300.6, >300.6 | 24-h dietary recall | Age, race, sex, systolic blood pressure, serum cholesterol, BMI, history of diabetes, physical activity, level of education, regular alcohol consumption, current cigarette smoking, saturated fat intake, and total energy intake | 8 | |||
| Cui et al., 2010 (49) | Foods + supplements; 12.5% (multivitamin) | Folate (μg/d) | Vitamin B-6 (mg/d) | VitaminB-12 (μg/d) | FFQ, 33 food items | Age, BMI, history of hypertension and diabetes, smoking status, ethanol and energy intakes, as well as intakes of SFAs and n–3 and n–6 PUFAs | 7 | |
| <272 | <0.79 | <4.5 | ||||||
| 272–351 | 0.79–0.96 | 4.5–5.9 | ||||||
| 352–430 | 0.97–1.11 | 6.0–7.6 | ||||||
| 431–535 | 1.12–1.32 | 7.7–9.8 | ||||||
| >536 | >1.33 | >9.9 | ||||||
| Dalmeijer et al., 2008 (26) | Foods + supplements; 7.1% (multivitamin) | Folate (μg/d):<169169–191191–215>215Median intake | FFQ, 178 food items | Age, hypertension, cholesterolemia, mean systolic blood pressure, total physical activity, BMI, smoking, diabetes, intake of energy, proteins, saturated fats, monounsaturated fats, polyunsaturated fats, alcohol, vitamin B-2, vitamin B-6, vitamin B-12, betaine, and choline | 8 | |||
| He et al., 2004 (25) | Foods + supplements; 0%–50.5% (B-complex) | Folate (μg/d) | Vitamin B-6 (mg/d) | Vitamin B-12 (μg/d) | FFQ, 131 food items | Age, BMI, physical activity, history of hypertension and hypercholesterolemia, smoking status, aspirin use, alcohol, and total calorie intakes of fiber, potassium, and vitamin E | 9 | |
| 262 | 1.8 | 5.0 | ||||||
| 336 | 2.3 | 7.2 | ||||||
| 413 | 2.8 | 10.0 | ||||||
| 547 | 4.2 | 13.3 | ||||||
| 821 | 10.9 | 21.0 | ||||||
| Median intake | ||||||||
| Larsson et al., 20081 (47) | Foods; 0% | Folate (μg/d)262300330360410 | Vitamin B-6 (mg/d)1.92.22.52.73.0 | Vitamin B-12 (μg/d)6.68.510.212.316.2 | FFQ, 276 food items | Age, supplementation group, total number of cigarettes smoked daily, BMI, systolic and diastolic blood pressure, serum total cholesterol, serum HDL cholesterol, histories of diabetes and coronary heart disease, leisure-time physical activity, and intakes of alcohol and total energy | 8 | |
| Luu et al., 2011 (50) | Foods + supplements; N.A. (folic acid) | Folate (μg/d):0–155 | FFQ, 66 food items | Age, gender, current smoking status, diabetes, caloric intake, and hypertension | 7 | |||
| 156–211 | ||||||||
| 212–278 | ||||||||
| ≥279 | ||||||||
| Marniemi et al., 2005 (45) | Foods; N.A. (nutritional) | Lowest tertileMiddle tertile | Dietary history interview | Age, gender, smoking, functional capacity, and weight-adjusted energy intake | 5 | |||
| Highest tertile | ||||||||
| Van Guelpen et al., 2005 (46) | Foods + supplements; 17.4%–28.6% (multivitamin) | Folate (μg/103kcal*d) | Vitamin B-12 (μg/103kcal*d) | FFQ, 84 food items | BMI, current smoking, cholesterol, diabetes, and hypertension. Plasma homocysteine | 6 | ||
| <105 | <132 | <2.1 | <2.0 | |||||
| 105–134, | 132–166, | 2.1–2.8 | 2.0–2.7 | |||||
| 134–173, | 166–274, | 2.8–3.3 | 2.7–3.7 | |||||
| >173(M) | >274 (F) | >3.3(M) | >3.7(F) | |||||
| Weng et al., 2008 (48) | Foods; 0% | Folate (μg/d):<297.33297.33–369.45>396.45 | FFQ, 49 food items | Age, sex, area, hypertension, use of antihypertensive drugs, diabetes mellitus, central obesity, alcohol consumption habits, smoking habit, sex-smoking habit interaction, BMI, self-report heart disease, hypercholesterolemia, hypertriglyceridemia, physical activity, fibrinogen, apoB, and plasminogen | 9 | |||
| Zhao et al., 2019 (27) | Foods + supplements; 7.73%–13.93% (B-vitamins) | Median intake vitamin B-6 (mg/d):1.311.531.691.872.2 | FFQ, 81 food items | Age at baseline, energy intake, education, income, occupation, smoke, alcohol, BMI, waist-hip ratio, physical activity, history of diabetes, hypertension, coronary heart disease, and stroke, vitamin B supplements use, menopausal status, and hormone replacement therapy | 7 | |||
| Zhao et al., 2019 (27) | Foods + supplements; 7.85%–12.8% (B-vitamins) | Median intake vitamin B-6 (mg/d):1.241.451.621.792.11 | FFQ, 77 food items | Age at baseline, energy intake, education, income, occupation, smoke, alcohol, BMI, waist-hip ratio, physical activity, history of diabetes, hypertension, coronary heart disease, and stroke, vitamin B supplements use, menopausal status, and hormone replacement therapy | 7 | |||