TABLE 1.
Ca:Mg Ratio Hypothesis Tested in Diet Studies1
| Study | Study design | Background diet or intervention | Average Ca, mg/d | Average Mg, mg/d | Median Ca:Mg ratio | Health outcome | Risk ratio |
|---|---|---|---|---|---|---|---|
| North Carolina–Louisiana Prostate Cancer Project (PCaP) (4) | Case-only study | Usual diet2 (with focus on dairy products) | AA, 980; EA, 11652 | AA, 421; EA, 4292 | AA, 2333; EA, 2803 | Ratio >2.50 increased odds of high-aggressive prostate cancer | OR, 1.65 [1.19–2.28] |
| Tennessee Colorectal Polyp Study (14) | Case-control | Usual diet2 | 981 | 321 | 2.78 | Ratio ≤2.78; increasing Mg associated with decreased risk of colorectal adenoma | OR, 0.38 [0.20–0.71; P < 0.01] |
| Western New York Exposures and Breast Cancer Study (WEB) (5) | Case-control | Usual diet2 | 1138 | 294 | 3.873 | Ratio >2.59; Mg was associated with lower risk of all cause-mortality | HR, 0.36 [0.17–0.77; P-trend = 0.01] |
| Vanderbilt, VA, Duke (18) | Case-control | Usual diet | Black, 544; White, 681 (median) | Black, 261; White, 322 (median) | Black, 2.00; White, 2.20 | Higher Ca:Mg ratio was related to a reduced odds of prostate cancer in Blacks, but not in Whites, for both low-grade (P-interaction, 0.04) and high-grade prostate cancer | OR, 0.66 [0.45–0.96; P = 0.03] |
| NHANES (15) | 1999–2006 Cohort | Usual diet2 and level of physical activity | 987–1221 | 302–375 | 3.25 | Higher physical activity associated with reduced risk of mortality due to cancer when Ca:Mg ratios were between 1.70 and 2.60 (interaction not significant) | HR, 0.48 [0.26–0.87; P < 0.001] |
| Shanghai Women's Study (12) | Prospective cohort | Usual diet | 493 | 279 | 1.704 | Ratio ≤1.70; Mg associated with increased risk of total mortality in women | Mg HR, 1.24 [1.02–1.51; P-trend = 0.02] |
| Shanghai Men's Health Study (12) | Prospective cohort | Usual diet | 513 | 298 | 1.704 | Ratio >1.70; Mg and Ca associated with reduced total mortality in men | Mg HR, 0.66 [0.50–0.88, P-trend = 0.01]; Ca HR, 0.59 [0.44–80, P-trend = 0.00] |
| Prostate, Lung, Colorectal, and Ovarian (PLCO) (13) | Prospective cohort | Screening tests vs. usual care (usual diet)2 | 1057–1161 | 395–431 | 2.50 | Ratio 1.70–2.50; Ca was associated with reduced risks of incident advanced adenoma and distal colorectal cancer | OR, 0.70 [0.49–1.01] |
| NIH-AARP Diet and Health Study (19) | Prospective cohort | Usual diet2 | 881 (median) | 358 (median) | 2.463 | Increased Mg was associated with a reduced risk of noncardiac gastric carcinoma; the associations did not significantly differ by ratio | |
| NIH-AARP Diet and Health Study (16) | Prospective cohort | Usual diet2 | 881 (median) | 358 (median) | 2.463 | Higher Mg intake was associated with an increased risk of esophageal adenocarcinoma when Ca:Mg ratios <1.70 | HR, 1.96 [1.01–3.77] |
| Calcium Polyp Prevention Study (3) | RCT | Calcium 1200 mg/d × 4 y | Ratio ≤2.60, 656; ratio >2.60, 1110 | Ratio ≤2.60, 321; ratio >2.60, 319 | 2.60 | Ratio ≤2.60; Ca was associated with a reduced risk of colorectal adenoma recurrence | RR, 0.68 [0.52–0.92; P- trend = 0.075 for interaction] |
| Personalized Prevention of Colorectal Cancer Trial (PPCCT) (17) | RCT | Personalized Mg supplementation | 1299 | 350 | 3.80 | Decreasing ratio to ∼2.30 improved cognitive function by 9.1% (P = 0.03) and modified APOE cytosine among those aged >65 y |
1
For studies that used control groups outcomes are compared with controls or reference tertile or quartile of intakes. Risk ratios are reported as HRs, ORs, or RRs and expressed with 95% CIs. AA, African Americans; Ca:Mg, calcium-to-magnesium; EA, European Americans; RCT, randomized controlled trial; RR, relative risk.
2
Total intakes include intake from supplements where noted.
3
Calculated average or median value.
4
Median ratio for the Shanghai study, men and women combined.