What foods have magnesium? Green leafy vegetables, nuts, seeds, whole grains, and legumes are amongst the richest dietary sources of this essential mineral. Magnesium supports over 300 enzymatic reactions in the body, including muscle and nerve function, energy production, and bone health. Despite its importance, many UK adults consume less than the recommended amount. Understanding which everyday foods contain magnesium and how to incorporate them into your diet can help you meet your daily requirements naturally, without the need for supplementation in most cases.

Why Magnesium Is Essential for Your Health

Magnesium is the fourth most abundant mineral in the human body and plays a vital role in over 300 enzymatic reactions. This essential nutrient is crucial for maintaining normal muscle and nerve function, supporting a healthy immune system, keeping your heartbeat steady, and helping bones remain strong. Magnesium also contributes to energy production at the cellular level and assists in the synthesis of DNA and proteins.

Within the body, approximately 60% of magnesium is stored in bone tissue, whilst the remainder is found in muscles, soft tissues, and bodily fluids. The mineral works closely with calcium to regulate muscle contraction and relaxation—magnesium allows muscles to relax whilst calcium triggers contraction. This partnership is particularly important for cardiac function, where magnesium helps maintain normal heart rhythm.

Magnesium also plays a significant role in glucose metabolism and insulin sensitivity. Observational studies suggest adequate magnesium intake may support healthy blood pressure levels and contribute to cardiovascular health, though supplementation is not routinely recommended for prevention or treatment of these conditions. The mineral is involved in the regulation of neurotransmitters, which send messages throughout the brain and nervous system, potentially influencing mood and cognitive function.

Despite its importance, the National Diet and Nutrition Survey (NDNS) indicates that many adults in the UK have intakes below the Reference Nutrient Intake (RNI), particularly among certain age groups. It's important to note that while intake may be below recommended levels, frank deficiency is uncommon in healthy adults. Understanding which foods contain magnesium and incorporating them into your daily diet is therefore essential for maintaining overall health and wellbeing.

Top Food Sources of Magnesium in the UK Diet

A varied diet incorporating whole foods provides the best approach to meeting your magnesium requirements. Green leafy vegetables are among the richest sources, with spinach, kale, and Swiss chard leading the way. A 100g serving of cooked spinach provides approximately 80mg of magnesium (about 30% of an adult's daily needs). The chlorophyll molecule that gives these vegetables their green colour contains magnesium at its centre, making them naturally abundant in this mineral.

Nuts and seeds are exceptionally magnesium-dense foods. Pumpkin seeds top the list with around 550mg per 100g, whilst almonds provide approximately 270mg, cashews 290mg, and Brazil nuts 375mg per 100g. A small handful (30g) of mixed nuts can contribute significantly to your daily magnesium intake. Chia seeds and flaxseeds are also excellent sources, easily incorporated into porridge, yoghurt, or smoothies.

Whole grains retain their magnesium content in the bran and germ, which are removed during refining. Brown rice, quinoa, wholemeal bread, and oats are valuable sources. A 150g serving of cooked brown rice provides about 65mg of magnesium, whilst a typical 40g portion of dry porridge oats contains approximately 55mg.

Legumes including black beans, chickpeas, lentils, and kidney beans are both affordable and magnesium-rich. A 100g serving of cooked black beans provides around 70mg. Dark chocolate (70% cocoa or higher) contains approximately 230mg per 100g, though it should be consumed in moderation due to its calorie and sugar content.

Fish such as mackerel, salmon, and halibut contribute modest amounts of magnesium alongside omega-3 fatty acids. Avocados, bananas, and dried figs are fruit sources worth including regularly. Fortified foods including some breakfast cereals may also contribute to magnesium intake, though checking labels is advisable as fortification levels vary.

It's worth noting that mineral content can vary by variety, growing conditions and processing methods. The UK Composition of Foods Integrated Dataset (CoFID) provides detailed information on the nutrient content of foods commonly consumed in the UK.

How Much Magnesium Do You Need Daily?

The recommended daily intake of magnesium varies according to age, sex, and life stage. In the UK, the Reference Nutrient Intake (RNI) established by the Department of Health provides guidance on adequate magnesium consumption:

• Adult men aged 19 and over: 300mg per day

• Adult women aged 19 and over: 270mg per day

• Children aged 0-3 months: 55mg per day

• Children aged 4-6 months: 60mg per day

• Children aged 7-12 months: 75mg per day

• Children aged 1-3 years: 85mg per day

• Children aged 4-6 years: 120mg per day

• Children aged 7-10 years: 200mg per day

• Boys aged 11-14 years: 280mg per day

• Girls aged 11-14 years: 280mg per day

• Boys aged 15-18 years: 300mg per day

• Girls aged 15-18 years: 300mg per day

Pregnant women do not require additional magnesium beyond the standard female RNI, as the body adapts to increase absorption efficiency during pregnancy. For breastfeeding women, UK guidance suggests maintaining the standard RNI is sufficient for most women.

These figures represent the amount needed to prevent deficiency in the majority of the population. The European Food Safety Authority (EFSA) has set slightly different values, with adequate intake levels of 350mg for men and 300mg for women.

Individuals with certain medical conditions, those taking specific medications, and older adults may have a higher risk of low magnesium levels. Long-term use of proton pump inhibitors or diuretics can reduce absorption or increase losses of magnesium, respectively. If you have concerns about your magnesium status, discussing this with your GP or a registered dietitian is advisable rather than self-supplementing.

Regarding supplements, the NHS notes that high doses (over 400mg per day) can cause diarrhoea. People with kidney disease should not take magnesium supplements unless advised by a clinician. If you do take supplements, be aware that magnesium can interact with certain medications and should be taken at least 2-4 hours apart from medicines such as levothyroxine, certain antibiotics, and bisphosphonates.

Signs You May Not Be Getting Enough Magnesium

Magnesium deficiency, clinically termed hypomagnesaemia, can develop gradually, and early symptoms may be subtle or non-specific. Muscle cramps and spasms are among the commonly reported signs, particularly affecting the legs and feet. These occur because magnesium is essential for proper muscle relaxation; without adequate levels, muscles may contract involuntarily. Night-time leg cramps are sometimes associated with low magnesium, though it's important to note that evidence for magnesium as a sole cause or treatment for idiopathic cramps is limited.

Fatigue and weakness may develop as magnesium is crucial for energy production within cells. Individuals may notice reduced exercise tolerance or persistent tiredness that does not improve with rest. Mental health changes including increased anxiety, irritability, or low mood have been associated with inadequate magnesium intake in some observational studies, though the relationship is complex and multifactorial.

Abnormal heart rhythms (arrhythmias) represent a more serious manifestation of magnesium deficiency. Magnesium helps regulate the electrical signals that coordinate heartbeat, and severe deficiency can lead to palpitations or irregular heart rhythm. Numbness and tingling in the extremities may occur due to magnesium's role in nerve function. Loss of appetite, nausea, and vomiting can appear in more pronounced deficiency states.

Certain groups face higher risk of inadequate magnesium intake. These include older adults (due to reduced dietary intake and absorption), individuals with gastrointestinal conditions such as Crohn's disease or coeliac disease (which impair absorption), people with type 2 diabetes (increased urinary losses), and those with alcohol dependence (multiple mechanisms affecting magnesium status).

When to contact your GP: If you experience persistent muscle cramps, unexplained fatigue, heart palpitations, or any concerning symptoms, consult your doctor rather than self-diagnosing magnesium deficiency. Blood tests can assess magnesium levels, though serum magnesium may not always reflect total body stores. Your GP can identify underlying causes and recommend appropriate management.

Seek urgent medical attention (call 999) if you experience chest pain, severe palpitations, collapse, or seizures. For urgent advice when your GP is unavailable, contact NHS 111.

Tips for Increasing Magnesium Through Your Diet

Optimising your magnesium intake through dietary sources is both achievable and sustainable with some straightforward strategies. Start your day with magnesium-rich foods by choosing porridge made with oats and topped with sliced banana, a tablespoon of pumpkin seeds, and a few squares of dark chocolate shavings. Alternatively, wholemeal toast with almond butter provides a substantial magnesium boost alongside healthy fats and protein.

Incorporate leafy greens daily by adding spinach or kale to smoothies, omelettes, curries, or pasta dishes. A large mixed salad with your lunch or dinner contributes valuable magnesium whilst providing fibre and other essential nutrients. Steaming or lightly cooking greens may help preserve nutrients compared to boiling in large amounts of water.

Choose whole grains over refined alternatives whenever possible. Swap white rice for brown rice or quinoa, select wholemeal bread instead of white, and opt for wholegrain pasta. These simple substitutions significantly increase magnesium intake whilst providing additional fibre and B vitamins. The refining process removes up to 80% of magnesium from grains, making whole grain choices particularly important.

Keep nuts and seeds readily available as convenient snacks. A small container of mixed nuts in your bag or desk drawer provides an easy magnesium boost between meals. Sprinkle seeds over salads, soups, or yoghurt to enhance both nutritional value and texture. Nut butters spread on fruit or wholegrain crackers make satisfying, magnesium-rich snacks.

Include legumes regularly in your meal planning. Adding chickpeas to salads, making bean-based soups or stews, or preparing hummus as a dip all contribute to magnesium intake. Legumes are also economical, versatile, and provide plant-based protein and fibre.

Be mindful of food preparation methods. Boiling vegetables in large amounts of water can leach magnesium into the cooking water, which is then discarded. Steaming, roasting, or stir-frying helps retain mineral content. If you do boil vegetables, consider using the cooking water in soups or sauces to recapture lost nutrients.

Limit processed foods, which are typically low in magnesium and other essential minerals. Focusing on whole, minimally processed foods naturally increases your intake of magnesium alongside other beneficial nutrients. Reading food labels can help identify fortified products that contribute to magnesium intake, though whole food sources should form the foundation of your diet.

For most people, meeting magnesium requirements through diet alone is entirely feasible with attention to food choices. Supplements should only be considered under medical guidance, as excessive magnesium intake from supplements can cause adverse effects including diarrhoea. The NHS advises that doses above 400mg per day may cause diarrhoea. People with kidney disease should not take magnesium supplements unless advised by a clinician.

If you do take magnesium supplements, be aware they can interact with certain medications. Take magnesium supplements at least 2-4 hours apart from medicines such as levothyroxine, certain antibiotics (tetracyclines/quinolones), and bisphosphonates. Always check with a pharmacist if you're unsure about potential interactions.

If you suspect side effects from magnesium medicines or supplements, you can report these via the MHRA Yellow Card scheme.

Frequently Asked Questions