By Stephen Daniells， 15-Mar-2010
Increased intakes of magnesium may reduce a man’s risk of colon cancer by over 50 per cent， says a new observational study from Japan.
Intakes of the mineral of at least 327 milligrams per day were found to reduce the risk of colon cancer by 52 per cent， compared to intakes less than 238 milligrams per day， while no benefits were observed in women， according to findings published in the Journal of Nutrition.
Being an epidemiological study， the findings do not prove causality， and additional studies， and particularly randomised trials， are needed to confirm the findings， said researchers from Japan’s National Cancer Center in Tokyo.
Dietary sources of magnesium include green， leafy vegetables， meats， starches， grains and nuts， and milk. Earlier dietary surveys show that a large portion of adults does not meet the RDA for magnesium (320 mg per day for women and 420 mg per day for men).
Magnesium has been heralded as an ingredient to watch for 2010. Indeed， a recent report from The Freedonia Group reported that global demand for nutrients and minerals will reach $12.6bn by 2013; a 6.4 per cent increase on last year’s level.
The report， World Nutraceutical Ingredients， highlighted magnesium as one of the minerals with fastest growth， along with calcium. Other fact growing ingredients included soy proteins and isoflavones， psyllium and resistant maltodextrin fibres， omega-3 fatty acids， probiotics， and carotenoids.
Study details
The Japanese researchers recruited 87，117 people with an average age of 57 and followed for about eight years. Dietary intakes were assessed using a food frequency questionnaire. Average intakes of magnesium for men and women were 284 and 279 milligrams per day.
During the course of the study， 689 and 440 cases of colorectal cancer in men and women were documented.
Men with the highest average intakes of magnesium (at least 327 mg/d) were associated with a 52 per cent lower risk of colon， but not rectal， cancer， compared to men who consumed the lowest average intakes.
“Increased intake of magnesium-rich foods is recommended if other studies， including randomized controlled trials， confirm our findings，” concluded the researchers.
Colorectal cancer accounts for nine per cent of new cancer cases every year worldwide. The highest incidence rates are in the developed world， while Asia and Africa have the lowest incidence rates.
It remains one of the most curable cancers if diagnosis is made early.
Magnesium for male， but not female， hearts
A recent review of the cardiovascular benefits of magnesium in the Journal of the American Academy of Nurse Practitioners， reported that increased intakes of the mineral may reduce the risk of coronary heart disease (CHD) in men， but the evidence is lacking for women.
And with the mineral being implicated in more than 300 biochemical reactions in the body， and toxicity issues being rare “oral magnesium supplementation is recommended”， concluded the reviewers Tavia Mathers and Renea Beckstrand from Brigham Young University.
Source: Journal of Nutrition
Volume 140， Pages 779-785
“High dietary intake of magnesium may decrease risk of colorectal cancer in Japanese men”
Authors: E. Ma， S. Sasazuki， M. Inoue， M. Iwasaki， N. Sawada， R. Takachi， S. Tsugane， Japan Public Health Center-based Prospective Study Group
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