Magnesium is one of the most abundant minerals in the body and plays an important role as a co-factor in more than 300 enzyme systems (16). Some magnesium health benefits include energy production, carbohydrate metabolism, bone health, muscle contractions and maintaining a normal heart rhythm (26).
How does the body absorb magnesium?
Magnesium is absorbed in the small intestine, stored in bone minerals and excess is excreted in the kidneys and faeces (13). About 50 to 60% of the magnesium in the body is inside bones, with the remainder residing in soft tissue (14). The amount stored inside bones depletes to nearly one-half (25).
Components of food can also influence the body's ability to absorb nutrients. Studies suggest that when the fibre is consumed in high amounts of 40-50g per day, this can lower magnesium absorption. (13, 14) Reduced magnesium absorption has also been found with a high intake of zinc (23) and dietary protein intake of less than 30g per day (11).
The body is quite smart at adapting its ability to absorb nutrients based on how much is eaten (22, 23). Absorption through the gut can increase up to 75% on low magnesium diets and reduce to 25% on high magnesium diets (21).
Women and men between the ages of 19-30 years old require 310mg and 400mg of magnesium each day, respectively, to meet the RDI (Recommended Dietary Intake) (16). After 30, this jumps even further for both genders, with males requiring 420mg per day and 320mg per day for females (16).
Despite its importance, the latest Australian Health Survey indicates that one in three Australians are failing to meet these recommendations (1). Inadequacy is highest in 14 to 18-year-old females, with 72% of females not meeting their requirements (1). Similar results have also been found in the United States and other western countries following dietary patterns similar to Australia.
What foods are rich in magnesium?
Luckily, this important mineral is widely found throughout the food supply in both plant and animal foods (16). Magnesium-rich foods include green vegetables, peas, beans and nuts, as well as some shellfish and spices (16).
The foods below are excellent sources of magnesium(7).
Magnesium health benefits
Here are several health benefits of magnesium and reasons why it's important to to get the recommended dose.
Reducing muscle cramps
A muscle cramp is a sudden, painful contraction of a muscle lasting a few minutes (14). There are multiple theories as to why muscle cramps occur during exercise, including poor diet, heavy sweating, dehydration, poor physical condition and inflexible muscles (10). Due to the role magnesium plays in muscle contraction and relaxation, it is thought to relieve muscle cramping. Unfortunately, studies that have tested the effect of supplementation on muscle cramps have shown that it provides no greater benefit than a placebo (9,10,17).
Improving heart health
One of the key benefits of magnesium is the role it may play in the prevention of heart disease and stroke. One large study of 313,000 people found that higher circulating levels in the blood were associated with a 30% lower risk of heart disease (4). Other studies have shown that there may also be an association between low dietary magnesium intake and a higher risk of stroke, high blood pressure and high cholesterol (2). However, more research is needed in this area.
Signs of magnesium deficiency
Testing for magnesium status can be challenging as blood levels of magnesium do not provide reliable information as to how much is stored within cells and bones (16). Deficiency is relatively rare in humans, as the kidneys limit urinary excretion of minerals (16). However, having a low intake over a long period of time and excessive loss of magnesium due to conditions such as chronic alcoholism, some chronic diseases, and the use of certain medications can lead to deficiency (6).
Signs deficiency can include:
- Loss of appetite
- Weight loss
- Muscle weakness
- Muscle spasms
Those most at risk of deficiency include people with gastrointestinal diseases such as inflammatory bowel diseases and bowel resections that may result in chronic diarrhoea or malabsorption (18). Some studies suggest that increased urinary magnesium excretion can occur with insulin resistance and/or type 2 diabetes (4, 18, 24).
Older adults have an increased risk of deficiency due to having lower dietary intake (8), reduced absorption from the gut with age (15) and a higher likelihood of consuming medication that interacts with magnesium status (3,12).
Should I supplement magnesium?
Our philosophy is always to focus on real, whole foods first before adding a supplement. A good rule of thumb to ensure you're getting enough of this essential micronutrient is to try to have a variety of different plant-based foods in your diet each day.
However, we also understand that it can be challenging to keep a healthy, balanced diet when life gets busy. This is especially important if you're in the at-risk category of magnesium deficiency or are a picky eater.
To learn more about supplements, take Vitable's quiz about your lifestyle, health and body goals.
Find out more about other areas that the above supplements can help you with:
*Always read the label. Follow the directions for use. If symptoms persist, talk to your health professional. Vitamin and/or mineral supplements should not replace a balanced diet.