Table 3.

Summary of prospective observational studies that examined the association between calcium supplement use and risk of cardiovascular disease

Source	Country	Study Design	Study Subjects	Calcium Supplement Use	Endpoints	Follow -up	Main Findings
Ascherio et al., 1998 [34]	United States	Cohort study	HPFS, 43,738 M, 40–75 y	Nonuser, < 400 mg/d, ≥400 mg/d	Incident stroke	8 y	RR in user ≥400 mg/d. vs. non-users:      0.88 (0.60–1.27) for total stroke      0.83 (0.52–1.34) for ischemic stroke
Bostick et al., 1999 [25]	United States	Cohort study	IWHS, 34,486 W, 55–69 y	0, 1–500, >500 mg/d	CHD mortality	8 y	RR in users vs. nonusers:      0.76 (0.58–1.00) for 1–500 mg/d,      0.88 (0.64–1.23) for >500 mg/d,      P trend=0.46.
Iso et al., 1999 [33]	United States	Cohort study	NHS, 85,764 W, 34–59 y	Nonuser, < 400 mg/d, ≥400 mg/d	Incident Stroke	14 y	RR in user ≥400 mg/d. vs. non-users:      0.75 (0.56–1.01).
Al-Delaimy et al., 2003 [28]	United States	Cohort study	HPFS, 39,800 M, 40–75 y	0, 57, 200, 325, 500, 1000 mg/d (Medians)	Incident CHD	12 y	RR for total CHD in the highest vs. the lowest quintile of users:      0.87 (0.64–1.19); P trend=0.31. RR for nonfatal MI in the highest vs. the lowest quintile of users:      1.02 (0.71–1.46); P trend=0.84. RR for CHD mortality in the highest vs. the lowest quintile of users:      0.61 (0.34–1.10); P trend=0.05.
Pentti et al., 2009 [36]	Finland	Cohort study	Kuopio Osteoporosis Risk Factor and Prevention Study, 10,555 W, 52–62 y	Nonuser, user	Incident CHD	6.55 y	HR in user vs. non-users:      1.24 (1.02–1.52) in entire cohort      1.26 (1.01–1.57) in postmenopausal women

Abbreviation: M: men; W: women; CHD: coronary heart disease; MI: myocardial infarction; RR: relative risk; HR: hazard ratio; HPFS: Health Professionals Follow-up Study; IWHS: Iowa Women Health Study; NHS: Nurses’ Health Study.