Nutritional News: Magnesium, the Quiet Mineral Behind 300 Enzymes

October 10, 2026

Series 13: Magnesium

Magnesium rarely makes headlines. It does little for supplement marketing compared with vitamin D or omega-3. Yet it takes part in more than 300 enzyme systems, and the research on how much we get from food, and what that means for long-term health, is more interesting than its profile suggests.

What magnesium does

According to the US National Institutes of Health Office of Dietary Supplements, magnesium acts as a cofactor in more than 300 enzyme systems. These include protein synthesis, muscle and nerve function, blood glucose control and blood pressure regulation. It is needed for energy production and for making DNA, RNA and the antioxidant glutathione. It also contributes to bone structure and helps move calcium and potassium across cell membranes, which supports nerve conduction, muscle contraction and normal heart rhythm.

How much do we need?

The NHS gives UK reference amounts of 300 mg a day for men and 270 mg a day for women aged 19 to 64. US recommended allowances are higher: 400 to 420 mg for adult men and 310 to 320 mg for adult women, depending on age.

Where it comes from

Magnesium sits at the centre of the chlorophyll molecule, and it is concentrated in the outer layers of seeds and grains. Whole plant foods are therefore the main dietary sources. The NIH food table lists the following seeds and nuts, all per 28 g serving:

Food	Serving	Magnesium (mg)
Pumpkin seeds, roasted	28 g	156
Chia seeds	28 g	111
Almonds, dry roasted	28 g	80
Cashews, dry roasted	28 g	74

The same table also lists leafy greens, beans, soya products and wholegrains, and notes that refining grains removes much of their magnesium.

Absorption is incomplete. The NIH estimates that about 30 to 40% of dietary magnesium is absorbed.

What the research says

Blood pressure. A Cochrane review of 12 trials (545 adults with hypertension) found a small average fall in diastolic pressure of about 2.2 mmHg. A separate meta-analysis of 22 trials reported falls of 3 to 4 mmHg systolic and 2 to 3 mmHg diastolic, with larger effects at supplemental doses above 370 mg a day. The DASH diet lowers blood pressure by around 5.5/3.0 mmHg, but because it changes many nutrients at once, magnesium's own contribution is hard to isolate.

Cardiovascular disease. Observational studies point in a consistent direction. In the ARIC cohort (14,232 adults), people in the highest quartile of serum magnesium had a 38% lower risk of sudden cardiac death. A meta-analysis of seven studies (241,378 participants) linked each extra 100 mg a day of intake to 8% lower total stroke risk. Observational data cannot show cause and effect, and the NIH notes that a large, well-designed clinical trial is still needed.

Type 2 diabetes. Cohort meta-analyses link each additional 100 mg a day of magnesium intake to about 15% lower diabetes risk (7 studies, 286,668 participants). A 2011 analysis found the association was significant mainly in people with a BMI of 25 or above. Trials of supplements in people who already have diabetes are small and inconsistent, and the American Diabetes Association states there is currently not enough evidence to recommend magnesium for improving glycaemic control.

Bone. Some population studies link higher magnesium intake to greater bone mineral density. A 30-day trial in 20 postmenopausal women found that supplementation suppressed markers of bone turnover. The NIH concludes that more research is needed before magnesium supplements can be recommended for preventing or managing osteoporosis.

Migraine. Three of four small placebo-controlled trials using up to 600 mg a day found modest reductions in migraine frequency, and the fourth found no benefit. The AAN/AHS guideline describes magnesium as “probably effective” for prevention. Because doses of this size exceed the supplement upper limit, use should be supervised by a clinician.

Who may fall short?

The NIH identifies several groups at higher risk of low magnesium status:

People with gastrointestinal conditions that reduce absorption (Crohn's disease, coeliac disease, bowel resection).
People with type 2 diabetes, who lose more magnesium in urine.
Older adults, who tend to absorb less and excrete more.
People with alcohol dependence.
Long-term users of loop or thiazide diuretics or proton pump inhibitors.

In NHANES 2013 to 2016, 48% of Americans consumed less than their estimated average requirement from food and drink.

Food versus supplements

The upper limit of 350 mg a day applies only to supplements and medicines, not to food. Magnesium from food poses little risk in healthy people. Higher supplement doses commonly cause diarrhoea, nausea and cramping. The NHS says up to 400 mg a day from supplements is unlikely to cause harm, and that short-term intakes above this can cause diarrhoea. Risk rises with impaired kidney function, so anyone with kidney disease should take advice before supplementing.

Authorised health claims

Under GB nutrition and health claims rules, magnesium has authorised claims. Magnesium contributes to a reduction of tiredness and fatigue, to normal energy-yielding metabolism, to normal functioning of the nervous system, to normal muscle function, to normal protein synthesis, to electrolyte balance and to the maintenance of normal bones and teeth. A food can only carry these claims if it meets the conditions of use set out in the rules.

Magnesium-containing foods in our range

Seeds, nuts and whole grains are the food groups that appear most often in magnesium tables. In our range these include pumpkin seed butter, sunflower seed butter, raw white sesame tahini, raw black sesame tahini, chia seeds, hulled hemp seeds, sprouted buckwheat and raw cashew butter. Check the nutrition panel on each pack for exact values.

Editorial note

This article summarises published research and reference data for general information. It is not medical advice. Anyone considering magnesium supplements, particularly people with kidney disease or on regular medication, should speak to a GP or pharmacist.