Magnesium is an essential mineral involved in over 300 enzymatic reactions throughout the body, supporting muscle and nerve function, bone health, heart rhythm, and energy production. Despite its importance, some UK population groups consume less than recommended amounts, particularly adolescents. Understanding which everyday foods contain magnesium and how to incorporate them into your diet is key to maintaining optimal health. This guide explores the best dietary sources of magnesium, daily requirements across different life stages, signs of inadequacy, and practical strategies for meeting your needs through food rather than supplements.

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. Research suggests adequate magnesium intake may support healthy blood pressure levels and contribute to cardiovascular health. The mineral is involved in the regulation of neurotransmitters, which send messages throughout the brain and nervous system. While associations between magnesium status and mood or cognitive function exist, evidence for benefits from supplementation remains mixed.

Despite its importance, the National Diet and Nutrition Survey indicates that some groups in the UK population consume less than the Reference Nutrient Intake (RNI), particularly adolescents, especially girls. Clinically significant deficiency is uncommon in healthy people with balanced diets but can occur with malabsorption conditions, certain medications, alcohol misuse, or uncontrolled diabetes. Understanding which foods contain magnesium and incorporating them into your daily diet is therefore important 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 (a typical 150g portion contains about 120mg). 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 concentrated sources of magnesium. Pumpkin seeds top the list with around 550mg per 100g (a 30g serving provides approximately 165mg), whilst almonds provide approximately 270mg, cashews 290mg, and Brazil nuts 375mg per 100g. A small handful (30g) of mixed nuts can contribute about 80mg to your daily magnesium intake. Chia seeds and flaxseeds are also excellent choices, 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 100g serving of cooked brown rice contains approximately 45mg of magnesium, whilst porridge oats provide around 140mg per 100g of dry weight (a typical 40g portion contains about 55mg).

Legumes including black beans, chickpeas, lentils, and kidney beans are both affordable and magnesium-rich. A 100g serving of cooked black beans provides roughly 70mg of magnesium. 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 meaningful amounts of magnesium alongside omega-3 fatty acids. Avocados, bananas, and dried fruits like figs also provide moderate amounts. Mineral water can be a supplementary source, with magnesium content typically ranging from 5-120mg per litre depending on the brand—check labels for specific information.

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. For adult men aged 19 and over, the RNI is 300mg per day. For adult women in the same age group, the recommendation is 270mg per day.

Pregnant and breastfeeding women do not require additional magnesium beyond the standard female RNI of 270mg daily in the UK. During pregnancy, the body adapts to increase absorption efficiency of various nutrients, including magnesium.

Children's requirements increase progressively with age. For infants, the UK uses 'safe intake' values rather than RNIs: 0–3 months require approximately 55mg daily, 4–6 months need 75mg, and 7–12 months need 85mg. Toddlers aged 1–3 years need 85mg, whilst children aged 4–6 years require 120mg daily. Children aged 7–10 years need 200mg daily. As children enter adolescence, requirements approach adult levels: both boys and girls aged 11–14 years require 280mg daily; adolescents aged 15–18 years need 300mg daily.

These figures represent the amount needed to prevent deficiency in 97.5% of the population. Individual requirements may vary based on factors including physical activity levels, certain medical conditions, and medication use. Some medications, particularly proton pump inhibitors (used for acid reflux) and certain diuretics, can affect magnesium absorption or increase urinary losses.

It is worth noting that the body tightly regulates magnesium levels, and healthy kidneys efficiently excrete excess amounts. Obtaining magnesium through food sources is preferable to supplementation. If considering supplements, the NHS advises not exceeding 400mg per day from supplements unless directed by a healthcare professional. People with kidney disease should consult their doctor before taking magnesium supplements.

Signs You May Not Be Getting Enough Magnesium

Magnesium deficiency, clinically termed hypomagnesaemia, can develop gradually and may initially present with subtle symptoms that are easily overlooked. Early signs often include fatigue, weakness, and loss of appetite. Some individuals experience nausea or general malaise. As magnesium plays a crucial role in muscle function, deficiency may manifest as muscle cramps, particularly in the legs, or muscle twitches and spasms. These symptoms occur because inadequate magnesium disrupts the balance between muscle contraction and relaxation.

Neurological symptoms can emerge as deficiency progresses. These may include numbness or tingling sensations, particularly in the extremities, due to magnesium's role in nerve signal transmission. Some people report increased irritability, mood changes, or difficulty concentrating. There is ongoing research into the relationship between magnesium status and mental health, though definitive causal links require further investigation.

Cardiovascular manifestations are particularly concerning. Magnesium deficiency can contribute to abnormal heart rhythms (arrhythmias), including palpitations. The mineral's role in maintaining normal heart rhythm means that severe deficiency may pose cardiac risks, though this typically occurs only in pronounced deficiency states.

Seek urgent medical help (999 or A&E) if you experience chest pain, severe palpitations with dizziness or fainting, new seizures, or severe muscle weakness, as these could indicate serious electrolyte imbalances requiring immediate attention.

Certain groups face elevated risk of inadequate magnesium intake. Older adults may have reduced dietary intake and decreased intestinal absorption. Individuals with gastrointestinal conditions such as Crohn's disease, coeliac disease, or chronic diarrhoea may experience impaired absorption. Type 2 diabetes can increase urinary magnesium losses, whilst excessive alcohol consumption interferes with magnesium metabolism. Long-term use of proton pump inhibitors (PPIs) has been associated with hypomagnesaemia, as highlighted in MHRA safety communications.

If you experience persistent symptoms suggestive of magnesium deficiency, consult your GP. Blood tests can assess serum magnesium levels, though this represents only 1% of total body stores and may not always reflect true deficiency. Your doctor can evaluate your symptoms in context, review medications that might affect magnesium status, and recommend appropriate dietary modifications or, if necessary, supplementation under medical supervision.

Tips for Increasing Magnesium Through Your Diet

Enhancing your magnesium intake through dietary modifications is both achievable and sustainable with practical strategies. Start with breakfast by choosing magnesium-rich options: porridge made with oats and topped with sliced banana, almonds, and a sprinkle of pumpkin seeds provides an excellent morning boost. Wholemeal toast with avocado offers another nutritious alternative.

Prioritise whole grains over refined options throughout the day. Replace white rice with brown rice or quinoa, choose wholemeal bread instead of white, and opt for wholegrain pasta. The refining process removes the magnesium-rich bran and germ, so whole grains retain significantly more of this essential mineral. When shopping, check food labels—products listing whole grains as the first ingredient are preferable.

Incorporate leafy greens daily. Add spinach or kale to smoothies, where the flavour is masked by fruit. Include a side salad with lunch or dinner, or stir leafy greens into soups, stews, and pasta dishes during the final minutes of cooking. Frozen spinach is convenient, economical, and retains its nutritional value—making it a practical option for increasing magnesium intake.

Snack strategically by keeping nuts and seeds readily available. A small handful of mixed nuts (approximately 30g) makes a satisfying snack that contributes meaningfully to daily magnesium intake. Spread nut butter on apple slices or wholegrain crackers. Add seeds to yoghurt, salads, or baked goods.

Include legumes regularly. Beans, lentils, and chickpeas are versatile, affordable, and magnesium-rich. Add them to salads, prepare hearty soups, or make vegetarian curries and chilli. Tinned varieties are convenient—simply rinse before use to reduce sodium content.

Consider dark chocolate as an occasional treat. Choose varieties with 70% cocoa content or higher for maximum magnesium benefit, but consume in moderation due to calorie density.

Drink mineral water as some brands contain significant magnesium. Check labels for mineral content—some waters provide 50mg or more per litre.

Remember that a balanced, varied diet incorporating these foods naturally provides not only magnesium but also other essential nutrients, fibre, and beneficial plant compounds that work together to support optimal health. If you're considering supplements, the NHS advises not exceeding 400mg per day from supplements unless recommended by a healthcare professional.

Frequently Asked Questions