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mrsD · 10-10-2006, 04:23 PM

Magnesium and exercise depletion:

Quote:

Crit Rev Food Sci Nutr. 2002;42(6):533-63. Related Articles, Links

Magnesium and exercise.

Bohl CH, Volpe SL.

University of Massachusetts, Department of Nutrition, Amherst 01003, USA.

Magnesium is an essential element that regulates membrane stability and neuromuscular, cardiovascular, immune, and hormonal functions and is a critical cofactor in many metabolic reactions. The Dietary Reference Intake for magnesium for adults is 310 to 420 mg/day. However, the intake of magnesium in humans is often suboptimal. Magnesium deficiency may lead to changes in gastrointestinal, cardiovascular, and neuromuscular function. Physical exercise may deplete magnesium, which, together with a marginal dietary magnesium intake, may impair energy metabolism efficiency and the capacity for physical work. Magnesium assessment has been a challenge because of the absence of an accurate and convenient assessment method. Recently, magnesium has been touted as an agent for increasing athletic performance. This article reviews the various studies that have been conducted to investigate the relationship of magnesium and exercise.

Publication Types:
Review
Review, Tutorial

PMID: 12487419 [PubMed - indexed for MEDLINE]

Magnesium and age:

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Magnes Res. 2001 Dec;14(4):283-90. Links
Prevalence of hypomagnesemia in an unselected German population of 16,000 individuals.

* Schimatschek HF,
* Rempis R.

Department of Pharmacology and Toxicology of Nutrition, University of Hohenheim, Stuttgart, Germany. schimats@uni-hohenheim.de

Based on a recently proposed reference range for plasma/serum Mg with its lower limit set at 0.76 mmol Mg/L the frequency of hypomagnesemia was evaluated in an unselected population group of about 16,000 individuals in total as well as in subgroups built according to sex, age and state of health. Hypomagnesemia was present in about 14.5 percent of all persons with generally higher frequencies in females and outpatients. In addition a slight but significant effect of age became overt. There was a continuous increase in the frequency of hypomagnesemia until the 29th year of life followed by a steady state. In elderlies, especially in old ladies, highest prevalence of up to one third of this subgroup occurred. Suboptimal levels were detected in 33.7 per cent of the population under study. These data clearly demonstrate that the Mg supply of the German population needs increased attention.

PMID: 11794636 [PubMed - indexed for MEDLINE]

Magnesium and celiac disease:

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Wiad Lek. 2001;54(9-10):522-31. Links
[Reasons for magnesium deficiency in children with coeliac disease]
[Article in Polish]

* Rujner J,
* Wojtasik A,
* Syczewska M,
* Stolarczyk A,
* Kowalska M,
* Iwanow K,
* Kunachowicz H,
* Socha J.

Instytut Pomnik-Centrum Zdrowia Dziecka w Warszawie.

Magnesium (Mg) deficiency is often noted in patients with coeliac disease (CD). The aim of the study was the analysis of the reasons of this deficiency in children with CD, diagnosed according to ESPGAN criteria. MATERIAL: The study was performed on 41 patients aged 6-18 years adhering to strict gluten-free diet GFD(+) for mean 11 years, with normal small intestine mucosa, and IgAEmA(-), and on 32 patients aged 5-17 years on gluten containing diet, with classical CD, silent CD or after gluten challenge--GFD(-). In this group the villous atrophy of the small intestine and IgAEmA(+) were observed. In 18 of these patients Mg deficiency was found using Mg-loading test (30 mmol/1.73 m2). METHODS: The following parameters were analysed: type of the disease, observance of gluten-free diet, sex, and living place. Mg, Ca, Na, protein, fat, and dietary fiber intake was assessed using food frequency questionnaire method, and steatorrhea using faecal fat excretion (g/24 h). RESULTS: The frequency of Mg deficiency was similar in both sexes, occasionally in children from small towns (4.5%), and more often in children from big cities (31.5%), and village (34.4%). Dietary Mg intake below RDA was observed in 23% of children from GFD(+) group, in 19% from GFD(-) one, and in 17.6% in children with Mg deficiency. Insufficient Mg intake was found in 18.2% of children from small towns, in 17.6% from big cities, and in 12.5% from villages; Ca in 36.6%, 58.8%, and 59.3%, and protein in 18.2%, 35.3%, and in 34.4% respectively. In all groups of children high intake of fat and Na was observed. Dietary fiber intake was within the recommended values. All children with classical CD had increased fat excretion (mean 25.9 g/24 h), in other patients it was within normal values [GFD(+) mean 1.95 g/24 h, in GFD(-) without diarrhoea 1.7 g/24 h. CONCLUSIONS: Magnesium deficiency in children with CD depends on the form of the disease, adhering to GFD, diarrhoea with steatorrhea, and/or low Mg intake with the diet.

PMID: 11816296 [PubMed - indexed for MEDLINE]

Poor food choices in USA:

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Arch Pediatr Adolesc Med. 2003 Aug;157(8):789-96. Related Articles, Links

Reported consumption of low-nutrient-density foods by American children and adolescents: nutritional and health correlates, NHANES III, 1988 to 1994.

Kant AK.

Department of Family, Nutrition, and Exercise Sciences, Queens College of the City University of New York, Flushing 11367, USA. ashima_kant@qc.edu

OBJECTIVE: To examine the contribution of foods of modest nutritional value to the diets of American children and adolescents. METHODS: The data were from the third National Health and Nutrition Examination Survey, 1988 to 1994, and included 4852 children and adolescents, aged 8 to 18 years. Foods reported in the 24-hour dietary recall were grouped into the following low-nutrient-density (LND) food categories: visible fat; table sweeteners, candy, and sweetened beverages; baked and dairy desserts; salty snacks; and miscellaneous. The independent association of the number of LND foods mentioned in the recall with intake of food groups, macronutrients, micronutrients, and body mass index was examined by means of regression procedures to adjust for multiple covariates. RESULTS: The LND foods contributed more than 30% of daily energy, with sweeteners and desserts jointly accounting for nearly 25%. Intakes of total energy and percentage of energy from carbohydrate and fat related positively, but percentage of energy from protein and dietary fiber (in grams) related inversely to the reported number of LND foods (P<.05). The reported number of LND foods was a negative predictor (P<.001) of the amount of nutrient-dense foods reported. The mean amount of reported intake of several micronutrients-vitamins A, B6, and folate, and the minerals calcium, magnesium, iron, and zinc-declined (P<.05) with increasing tertiles of reported number of LND foods. The LND food reporting was not a significant predictor of body mass index. CONCLUSION: High LND food reporting was related to higher energy intake but lower amounts of the 5 major food groups and most micronutrients.
PMID: 12912785 [PubMed - indexed for MEDLINE]

and also:

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J Am Diet Assoc. 2002 Apr;102(4):530-6. Related Articles, Links

Using Dietary Reference Intake-based methods to estimate the prevalence of inadequate nutrient intake among school-aged children.

Suitor CW, Gleason PM.

Mathematica Policy Research, Princeton, NJ, USA.

OBJECTIVE: To estimate the prevalence of inadequate usual intakes of nutrients by school-aged children. DESIGN: A descriptive study using data from the US Department of Agriculture 1994 to 1996 Continuing Survey of Food Intake by Individuals. Each subject provided two 24-hour recalls. We adjusted for day-to-day variation in nutrient intake and estimated the percentage of children with intakes below the Estimated Average Requirement (EAR) using the Software for Intake Distribution Estimation Program. SUBJECTS: A national sample of noninstitutionalized children aged 6 to 18 years (N=2,692). STATISTICAL ANALYSES: Chi2 tests showed that background characteristics or percentages with intakes below the EAR were the same across the 6 gender-age and racial/ethnic groups. The SUDAAN statistical package was used to account for the complex sample design. RESULTS: Usual intakes were more favorable for 5 B vitamins and iron than for the other nutrients examined. High percentages of children had intakes below the EAR for vitamin E. Many children aged 9 years and older had intakes below the EAR for folate and magnesium. Females aged 9 years and older had low calcium intakes relative to the Adequate Intake value. Females aged 14 to 18 years were at highest risk of usual intakes that did not meet the EARs. Few males in this age group met the EAR for vitamin E or magnesium. APPLICATIONS: Females aged 14 to 18, in particular, should be targeted for efforts to improve nutrient intakes. Studies should monitor children's usual nutrient intakes after adjusting for day-to-day variation.

PMID: 11985410 [PubMed - indexed for MEDLINE]

Wearing contacts? Have corneal issues?

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Cornea. 2003 Jul;22(5):448-56.Click here to read Links
Corneal changes in magnesium-deficient rats.

* Gong H,
* Takami Y,
* Kitaoka T,
* Amemiya T.

Department of Ophlamology and Visual Sciences, Nagasaki Univerity School of Medicine, Japan. hgong@net.nagasaki-u.ac.jp

PURPOSE: The purpose of the current study is to investigate the cornea in magnesium (Mg) deficiency and elucidate the local function of trace elements. METHODS: After delivery, mother Wistar Kyoto rats were fed a low Mg diet containing 0.1 mg Mg/100 g diet with all other nutrients and distilled and deionized water. Infant rats were suckled by their mothers for 21 days and then fed the same Mg-deficient diet. Control mother rats were fed commercial rat pellets containing 24 mg Mg/100 g diet and all other nutrients. The corneas were examined by electron microscopy at 6 weeks of age. RESULTS: In the Mg-deficient rats, serum Mg levels were significantly lower and calcium (Ca) levels higher than in the control rats. The corneas of Mg-deficient rats showed decreased microvilli and microplicae in the epithelial cells of the most superficial layer, increased mitochondria with abnormal shapes in the basal cells in the epithelium, condensed chromatin in the nuclei of the basal cells, and high density deposits and macrophage-like cells in the subepithelium of the stroma. Mg-deficient rats had pentagonal and square endothelial cells. CONCLUSION: Since Mg2+ has biologic functions including structural stabilization of protein, nucleic acids, and cell membranes, Mg deficiency may induce changes in the corneal surface and nuclei of corneal epithelial and endothelial cells. These disturbances may interfere with protection from infections, foreign bodies, dryness, and direct exposure to air. Thus, Mg is essential for the cornea to maintain normal structure and function.

PMID: 12827051 [PubMed - indexed for MEDLINE]