Table 2. Relative risks (RRs, 95% CIs) for incident colorectal cancer by deciles of total magnesium intake in the Nurses’ Health Study (1980–2008).

	Deciles of total magnesium intake: median (range, mg per day)
	D1: 211 (<230)	D2: 242 (230–251)	D3: 260 (252–268)	D4: 275 (269–282)	D5: 289 (283–297)	D6: 304 (298–311)	D7: 318 (312–328)	D8: 336 (329–347)	D9: 359 (348–376)	D10: 401 (>376)	P for trend
Colorectal cancer (n=1601)
No. of cases	165	169	155	144	149	161	154	164	181	159
Person-years	216 769	222 057	225 281	223 824	226 180	223 364	225 936	224 011	226 164	225 126
Model 1a	1.0 (Reference)	0.93 (0.75, 1.15)	0.81 (0.65, 1.01)	0.72 (0.58, 0.91)	0.74 (0.59, 0.92)	0.77 (0.62, 0.95)	0.72 (0.57, 0.89)	0.75 (0.60, 0.93)	0.80 (0.64, 0.98)	0.67 (0.53, 0.83)	<0.001
Model 2b	1.0 (Reference)	0.97 (0.78, 1.20)	0.86 (0.69, 1.07)	0.78 (0.62, 0.97)	0.80 (0.64, 1.00)	0.84 (0.67, 1.05)	0.81 (0.64, 1.01)	0.85 (0.68, 1.06)	0.92 (0.74, 1.14)	0.78 (0.63, 0.98)	0.09
Model 3c	1.0 (Reference)	0.96 (0.77, 1.19)	0.85 (0.68, 1.07)	0.78 (0.61, 0.98)	0.82 (0.64, 1.03)	0.86 (0.68, 1.10)	0.84 (0.66, 1.08)	0.91 (0.72, 1.16)	1.02 (0.81, 1.31)	0.93 (0.73, 1.22)	0.77
Colon cancer (n=1252)
No. of cases	132	127	123	113	111	128	123	128	150	117
Person-years	216 799	222 088	225 307	223 847	226 211	223 394	225 963	224 046	226 191	225 165
Model 1a	1.0 (Reference)	0.86 (0.68, 1.10)	0.79 (0.62, 1.02)	0.70 (0.54, 0.90)	0.68 (0.53, 0.87)	0.75 (0.59, 0.96)	0.70 (0.55, 0.90)	0.71 (0.56, 0.91)	0.81 (0.64, 1.02)	0.60 (0.46, 0.77)	<0.001
Model 2b	1.0 (Reference)	0.90 (0.70, 1.15)	0.84 (0.66, 1.08)	0.74 (0.58, 0.96)	0.73 (0.57, 0.95)	0.82 (0.64, 1.05)	0.79 (0.61, 1.01)	0.80 (0.62, 1.03)	0.93 (0.73, 1.18)	0.70 (0.54, 0.90)	0.06
Model 3c	1.0 (Reference)	0.89 (0.69, 1.14)	0.83 (0.64, 1.07)	0.74 (0.57, 0.96)	0.74 (0.56, 0.97)	0.83 (0.64, 1.09)	0.81 (0.62, 1.07)	0.84 (0.64, 1.11)	1.01 (0.77, 1.33)	0.81 (0.61, 1.10)	0.77
Rectal cancer (n=349)
No. of cases	33	42	32	31	38	33	31	36	31	42
Person-years	216 881	222 161	225 392	223 929	226 277	223 469	226 048	224 115	226 294	225 227
Model 1a	1.0 (Reference)	1.19 (0.75, 1.89)	0.86 (0.53, 1.41)	0.83 (0.51, 1.36)	0.98 (0.61, 1.57)	0.83 (0.51, 1.34)	0.77 (0.47, 1.26)	0.90 (0.56, 1.45)	0.73 (0.45, 1.20)	0.96 (0.61, 1.53)	0.31
Model 2b	1.0 (Reference)	1.26 (0.79, 1.99)	0.93 (0.57, 1.52)	0.91 (0.56, 1.50)	1.09 (0.68, 1.75)	0.92 (0.57, 1.50)	0.88 (0.54, 1.45)	1.05 (0.65, 1.70)	0.86 (0.52, 1.42)	1.17 (0.73, 1.86)	0.97
Model 3c	1.0 (Reference)	1.26 (0.78, 1.98)	0.94 (0.57, 1.55)	0.93 (0.55, 1.54)	1.14 (0.69, 1.87)	0.99 (0.58, 1.66)	0.97 (0.57, 1.65)	1.19 (0.71, 2.03)	1.04 (0.60, 1.82)	1.54 (0.90, 2.66)	0.23

Abbreviations: CI=confidence interval; MET=metabolic equivalent.

^aModel 1 was adjusted for age (in months).

^bModel 2 was adjusted for age (in months), smoking before age 30 (0, 1–4, 5–10, or >10 pack-years), history of colorectal cancer in a parent or sibling (yes, no), history of endoscopy (yes, no), regular aspirin use (yes, no), body mass index (<25, 25–<30, ⩾30 kg m^–2), physical activity (<3, 3–<27, ⩾27 MET-hours per week), postmenopausal hormone use (premenopausal, never, past, or current user).

^cModel 3 was further adjusted for consumption of processed meat (quintiles), consumption of beef, pork, or lamb as a main dish (quintiles), alcohol consumption (0–<5, 5–<10, 10–<15, or ⩾15 g per day), energy-adjusted total calcium intake (quintiles), total folate (quintiles), total vitamin D intake (quintiles), and total energy intake (quintiles).