Am J Gastroenterol. 2008;103:375-382.Reuters Health Information 2008. © 2008 Reuters Ltd.
Clinical ContextOverprocessing of foods has contributed to
a decline in
magnesium intake in the United States and other
industrialized countries because magnesium is lost during food
processing.
Gallstone disease is common in western countries, and the
most common
gallstones are cholesterol stones. Magnesium deficiency may
play a role in the hypersecretion of insulin, leading to cholesterol
formation and gallstones, whereas adequate magnesium intake may
decrease gallstone formation by enhancing gallbladder emptying and
decreasing biliary stasis. Dietary sources of magnesium include fish
and whole grains, green vegetables, legumes, nuts, and seeds.
This is an analysis within a prospective cohort study of
men in the
Health Professionals Follow-Up Study conducted between 1986 and 2002 to
examine the association between magnesium intake and the risk for
symptomatic gallstone disease. The participants were dentists,
veterinarians, osteopathic physicians, and podiatrists aged 40 to 75
years at baseline. They were mailed a biennial questionnaire about
medical history and conditions, and diet was assessed by a
semiquantitative food frequency questionnaire (SFFQ) every 4 years.
Study HighlightsIncluded were men who completed the questionnaire on food frequency and disease incidence.Excluded were those who reported a cholecystectomy or gallstone
disease at baseline, cancer, daily energy intake outside the range of
800 to 4200 kcal/day, or who left 70 or more food items blank on the
dietary questionnaire.The SFFQ had 131 items, and frequency of intake in the previous
year was assessed with use of 9 options from "never" or "less than once
a month" to "6 or more times a day."Nutrient scores were computed by frequency of consumption of each
unit of food and nutrient content from the food composition tables of
the Harvard Composition Database and the US Department of Agriculture
supplemented with manufacturers'' data.Total magnesium intake was estimated from dietary and supplemental intake of magnesium.Primary outcome was incident symptomatic gallstones, documented by
responses to questions about undergoing cholecystectomy or having a
diagnosis of gallstone disease from a clinician.441 men with a self-reported diagnosis had the diagnosis confirmed
by medical record review, and only 1 diagnosis was not confirmed.Those with asymptomatic gallstone disease or with a subsequent diagnosis of cancer were excluded from analysis.Cox proportional hazards regression model was used to calculate
relative risks (RRs) of symptomatic gallstones in relationship to
magnesium intake.Multivariate analyses were conducted controlling for gallstone risk
factors such as obesity, parity, smoking, alcohol, and use of
nonsteroidal anti-inflammatory drugs.Magnesium from dietary sources accounted for approximately 98% of
Total magnesium intake, with a median daily intake of 334
mg vs total
intake of 342 mg (close to recommended US allowance of 350 mg daily for
men).At baseline, men with higher magnesium intake were less likely to
be current smokers, were more physically active and lighter, and
consumed less saturated and monounsaturated fats, with higher intake of
protein, carbohydrates, caffeine, and fiber.The study population consisted of 42,705 men, and the return rate of biennial questionnaires was 94%.During 560,810 person-years of follow-up. 2195 symptomatic
gallstones were documented, of which 1297 cases required
cholecystectomy.The median magnesium intake for the lowest to the highest quintiles
were less than 288 mg/day, 288 to 323 mg/day, 324 to 359 mg/day, 360 to
409 mg/day, and more than 409 mg/day, with a 1.7-fold increase from the
lowest to the highest quintile of intake.Total magnesium intake was associated with a decreased risk for gallstones in the age-adjusted and multivariate models.The age-adjusted RR for the highest vs the lowest quintile of total
magnesium intake and dietary magnesium was 0.67 and 0.67, respectively (P for trend = .001).The multivariate RR for total magnesium intake and dietary
magnesium in the highest vs the lowest quintile was 0.72 and 0.68,
respectively (P for trend = .0006).For a 100-mg increase in dietary magnesium intake, the multivariate RR was 0.86.The association was dose dependent and remained robust after controlling for diabetes mellitus and asymptomatic gallstones.Intake of supplementary magnesium was not inversely associated with
gallstones, but the authors suggested that this was because of the low
overall intake (2% of total magnesium) of supplementary magnesium.
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