The central role of magnesium in skeletal muscle: from myogenesis to performance.

A physiological concentration of magnesium (Mg) is essential for optimal skeletal muscle function. Indeed, Mg plays a crucial role during the differentiation process (myogenesis), in muscle fiber composition, muscle contraction and performance. This narrative review describes in detail the relevance of Mg in skeletal muscle, highlighting the importance of adequate Mg intake to ensure optimal skeletal muscle cell function and performance in individuals of all ages.

Eicosanoids and Oxylipin Signature in Hereditary Hemochromatosis Patients Are Similar to Dysmetabolic Iron Overload Syndrome Patients but Are Impacted by Dietary Iron Absorption.

INTRODUCTION: Oxylipins are mediators of oxidative stress. To characterize the underlying inflammatory processes and phenotype effect of iron metabolism disorders, we investigated the oxylipin profile in hereditary hemochromatosis (HH) and dysmetabolic iron overload syndrome (DIOS) patients. METHODS: An LC-MS/MS-based method was performed to quantify plasma oxylipins in 20 HH and 20 DIOS patients in fasting conditions and 3 h after an iron-rich meal in HH patients. RESULTS: Principal component analysis showed no separation between HH and DIOS, suggesting that the clinical phenotype has no direct impact on oxylipin metabolism. 20-HETE was higher in DIOS and correlated with hypertension (p = 0.03). Different oxylipin signatures were observed in HH before and after the iron-rich meal. Discriminant oxylipins include epoxy fatty acids derived from docosahexaenoic acid and arachidonic acid as well as 13-HODE and 9-HODE. Mediation analysis found no major contribution of dietary iron absorption for 16/22 oxylipins significantly affected by the meal. DISCUSSION: The oxylipin profiles of HH and DIOS seemed similar except for 20-HETE, possibly reflecting different hypertension prevalence between the two groups. Oxylipins were significantly affected by the iron-rich meal, but the specific contribution of iron was not clear. Although iron may contribute to oxidative stress and inflammation in HH and DIOS, this does not seem to directly affect oxylipin metabolism.

Métodos para la determinación del estado del magnesio en humanos / Methods of assessment of magnesium status in humans / Métodos para a determinação do estado do magnésio em humanos

En la actualidad, datos epidemiológicos sugieren que, en países occidentales, la ingesta de magnesio no satisface la ingesta recomendada, lo que apoya un riesgo de deficiencia de magnesio latente en estas poblaciones. La evaluación del estado de magnesio sigue siendo un desafío para el laboratorio clínico ya que el magnesio se encuentra distribuido mayoritariamente en el hueso y tejidos blandos. Existe la necesidad de conciliación entre una prueba de fácil acceso, rápida, sensible y representativa del magnesio intracelular. La utilidad de diferentes biomarcadores en sujetos sanos ha sido evaluada; se ha reportado que el magnesio en plasma, eritrocitos y orina parecen ser biomarcadores sensibles a la ingesta dietética y útiles como biomarcadores en la población general. Sin embargo, esto no es concluyente, ya que se resalta que aún se requieren estudios mejor diseñados, que impliquen factores como mayor población empleada, dosis y tiempo de suplementación. El progreso en la genética y la genómica abren perspectivas interesantes en la búsqueda de estos biomarcadores que permitan cuantificar los niveles de magnesio celular así como también las reservas de todo el cuerpo, para poder así establecer recomendaciones dietéticas mejor ajustadas a la población.

Epidemiological studies suggest that dietary magnesium in the Western countries does not meet the recommended intake, supporting a risk of latent magnesium deficiency with Western diet behavior. Assessment of magnesium status remains a major challenge for the clinical laboratory, since, magnesium storage is mostly found in bone and soft tissues. The conciliation between an easy obtained sample, rapid and robust laboratory test, and the parameter representative for intracellular magnesium is extremely difficult to reach. In a current systematic review study, the usefulness of magnesium status biomarkers in healthy subjects has been evaluated. It is proposed that plasma and erythrocyte magnesium, and urinary magnesium excretion which respond to dietary manipulation appear to be useful biomarkers in the general population. However, it is emphasized that well-designed studies of sufficient size with varying doses and duration of magnesium supplementation are still required. The development of specific and sensible biomarkers, making it possible to obtain cell magnesium levels as well as body magnesium pool evaluation, relevant to study individuals, small and large populations, remains a major challenge for the assessment of magnesium status. A progress in genetics and genomics opens new interesting perspectives in the search of these biomarkers.

Na atualidade, dados epidemiológicos sugerem que, nos países ocidentais, a ingestão de magnésio não supre a ingestão recomendada, o que apoia um risco de deficiência de magnésio latente nestas populações. A avaliação do estado do magnésio continua sendo um desafio para o laboratório clínico, visto que o magnésio se encontra distribuído principalmente no osso e nos tecidos moles. Há a necessidade de conciliar evidência facilmente acessível, rápida, sensível e representativa do magnésio intracelular. A utilidade de vários biomarcadores em indivíduos saudáveis foi avaliada, e foi relatado que o magnésio em plasma, eritrócitos e urina parecem ser biomarcadores sensíveis à ingestão dietética e úteis como biomarcadores na população geral. No entanto, esta não é conclusiva, uma vez que se destaca que são requeridos ainda estudos melhor desenhados, envolvendo fatores como utilização de maior população, dosagem e tempo de suplementação. Um avanço na genética e na genômica abre perspectivas interessantes na busca desses biomarcadores para poder quantificar os níveis de magnésio celular bem como as reservas do corpo inteiro, e assim poder estabelecer melhores recomendações na dieta adaptadas à população.