Disclaimer: This series is for educational purposes only and is not meant for diagnostic use.
In today's nutrient spotlight we will be talking about the micronutrient magnesium. A micronutrient is a nutrient that the body needs in small amounts. Magnesium is a mineral and is involved in a number of key biological processes inside the body. Some of these processes include: regulation of blood pressure, nerve and muscle function, protein synthesis etc. Magnesium is quite abundant in the body with approximately 60% stored in the bones. It is also involved in metabolic pathways that produce energy for the cells (I will have a dedicated blogpost about these pathways later). Magnesium is also a necessary factor for the transport of other minerals across the cell membrane and into the cell like calcium and potassium. This is important for regulating things like muscle contraction, heart rhythm and also nerve impulses. Magnesium is also important for bone health maintenance as it participates in the chemical reaction that converts vitamin D to its active form which we know from the precious nutrient spotlight is important for the absorption of nutrients like calcium and phosphorus (important for bone mineralization). As mentioned above it helps in the mobilization of calcium which is another nutrient involved in bone mineralization. It goes without saying that a severe deficiency in magnesium will negatively impact these functions. Additionally, because magnesium is involved in these functions, diseases affecting them involve magnesium. For example disruptions in magnesium balance in the body is involved in hypertension and heart disease as well as muscle or nerve dysfunction.
Magnesium sources include: Green leafy veggies like spinach and kale, Legumes such as edamame and black beans, nuts such as almonds, peanuts, cashews, seeds like chia and pumpkin seeds. You will also find it in fiber rich foods like oats, whole wheat bread and also in salmon, yogurt, milk etc.
Recommended Dietary Allowance for Magnesium
The recommended dietary allowance (this details the recommended intake of a nutrient that one should aim for daily to maintain health) for magnesium varies by age and sometimes by sex.
1-3yrs: 80mg
4-8yrs: 130mg
9-13yrs: 240mg
14-18yrs: Males- 410mg Females- 360mg
19-30 yrs: Males- 400mg, Females- 310mg
Over 31yrs: Males- 420mg, Females- 320mg
Magnesium Status, Intake and Deficiency
The body will absorb up to 40% of the magnesium that we consume. Balance of magnesium inside the body is controlled primarily by the kidneys which under normal/healthy circumstances will excrete a certain amount of magnesium in the urine. However, if there is a deficiency, the kidneys will hold on to all the magnesium available and it will not be excreted. It is because of this reason why magnesium deficiency is not very typical in healthy people. The deficiency will start to manifest when a person is consistently not intaking magnesium. Certain groups have a higher likelihood of developing a magnesium deficiency. These groups include people who have gastrointestinal (GI) dysfunction eg. Chronn's Disease where significant parts of the intestines are affected which results in malabsorption of a number of nutrients like magnesium. The same is true for people who have parts of their GI tract surgically removed (as in bariatric surgeries). Other groups at risk include the elderly population (because absorption of the nutrient by the gut decreases as we age and also excretion of magnesium increases as we age) or people who experience chronic alcoholism because they tend to vomit a lot which leads to loss of the nutrient and also kidney function is affected by over consuming alcohol.
Magnesium status is hard to assess in the clinic because most of it is stored in your bone and cells and the little that is present in the blood cannot accurately represent your overall status. Some clinicians may use a persons dietary intake (from a dietary recall/ food frequency questionnaire) to determine magnesium status but this is mostly estimation. If you think you have a magnesium deficiency incorporating more magnesium rich foods would be a good start. Common symptoms of magnesium deficiency include nausea and vomitting,weakness etc. For more severe deficiency symptoms include: numbness or tingling, muscle cramps, abnormal heart rhythm etc. Severe magnesium deficiency can also lead to a deficiency in calcium and potassium because it is important for their mobilization into the cells.
To end, as always I have to extend caution when considering supplements. An excess of magnesium intake from food does not have adverse effects on our health because as mentioned before the kidneys will excrete what you don't need. However, too much magnesium from supplements can lead to diarrhea and stomach cramps so please be careful and don't just take supplements on a whim. Please talk to your doctor before taking supplements.
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