We discussed micronutrients in episode #7 of our podcast, Nutrition: the ABC of almost everything. These include minerals, including magnesium. If you enjoy reading about nutrition, you may already know about the importance of magnesium in sport.

Why does it matter? Read on.

What are the benefits of magnesium?

Why do we need magnesium? This does not mean that a supplement is 100% necessary: not everyone needs a supplement. The aim is to meet the recommended intake through food where possible.

Magnesium is an essential mineral and electrolyte with a key role in bodily function.

It is needed for functions including muscle contraction and blood pressure regulation.

Who would not want their muscles to function properly?

Magnesium in an athlete’s diet

As an athlete, you may wonder why magnesium-containing sports supplements are often recommended when training hard.

In sport, magnesium participates in many processes affecting performance, from muscle contraction and oxygen uptake to energy production and electrolyte balance.

Research has also explored magnesium intake before bed and improved sleep. Rest is essential for physical adaptations to exercise, so this is another area of interest.

Despite its importance in sport, intake can be overlooked. Many people have magnesium intakes below their needs, and athletes can be particularly vulnerable to inadequate magnesium status.

In people with inadequate intake, ensuring sufficient magnesium through food or appropriate supplements can have beneficial effects on performance.

Great! Now you know why magnesium matters for athletes.

How does magnesium help muscles?

During exercise, magnesium moves towards sites of energy production. For example, during strength exercise, it moves towards the muscles where the action is happening.

Its role in muscle function has been widely studied. It participates in energy metabolism and supports muscle contraction and relaxation. Good muscular performance is associated with adequate blood magnesium levels.

Suboptimal magnesium status or deficiency can contribute to inefficient energy metabolism and a poorer cardiorespiratory response. Magnesium deficiency can disrupt neuromuscular function, and insufficient magnesium levels may contribute to muscle cramps.

How much magnesium does an athlete need?

The general adult intake figures presented here are:

For men aged 18–30, 400 mg daily; for women aged 18–30, 300 mg.
Above 30 years, these figures rise to 410 mg for men and 310 mg for women.

Athletes may have higher needs, with estimates of 10–20% above the general population. Requirements depend on the individual, the sport and the conditions, including humidity and temperature.

Intense exercise, particularly endurance activity such as triathlon, running and cycling, increases losses through urine and sweat. Greater training and magnesium losses may require higher intake. Around exercise, electrolyte supplementation may be worth assessing.

When should magnesium be taken?

First, consider supplementation when deficiency is identified. A deficiency is described here using serum levels below 1.82 mg/dl, with an optimal range given as 2.06–2.4 mg/dl.

Who may need particular attention to magnesium levels?

People with diabetes, cardiovascular disease, osteoporosis, sleep problems or chronic fatigue.
People eating a diet high in salt, ultra-processed foods, soft drinks and alcohol.
People with a low intake of nuts, vegetables, pulses and fruit.
People taking diuretics, antacids, oral contraceptives or antibiotics.

Symptoms of magnesium deficiency

Potential symptoms of magnesium deficiency include leg cramps, dizziness, digestive problems, fatigue, irregular heartbeat, headache and irritability.

An intake below 260 mg/day in male athletes or 220 mg/day in female athletes may contribute to magnesium deficiency. Magnesium supplementation or increased dietary intake can have performance benefits in people who are deficient.

Magnesium supplementation

The supplement doses discussed range from 50–500 mg/day. Amounts above 600 mg/day can cause adverse effects such as abdominal pain and diarrhoea. Agree an appropriate dose with a professional who can assess your individual case.

As magnesium intake rises, the proportion absorbed falls, reducing its percentage bioavailability. Dividing intake throughout the day may therefore be useful. This also supports the principle that supplements are unnecessary when food already meets your needs: the body limits absorption and eliminates excess magnesium.

Focus on meeting requirements through food and assess the need for supplements, particularly in endurance athletes. Appropriate electrolyte intake during exercise and magnesium-rich foods afterwards can help support adequate status.

Magnesium-rich foods

These foods can be useful additions to your diet, provided they are suitable for your individual circumstances:

Seeds: sesame, pumpkin and sunflower.
Nuts: almonds, hazelnuts, cashews and walnuts.
Fruit: bananas, watermelon and avocado.
Pulses: pinto beans and lentils.
Wholegrains: oats, brown rice and whole wheat.

Knowing where to find magnesium helps you meet your needs through food. We recommend professional guidance, particularly if you exercise regularly. A sports nutritionist designs your nutrition plan to provide the recommended macro- and micronutrient intake for your activity.