Magnesium is essential for over 300 enzymatic reactions in the body, supporting muscle and nerve function, bone health, heart rhythm, and energy production. Despite its importance, many people in the UK do not meet recommended intake levels. Understanding which foods are rich in magnesium and how to incorporate them into your daily diet is crucial for maintaining overall health. This guide explores the best dietary sources of magnesium, recommended intake levels, signs of deficiency, and practical strategies to optimise your magnesium consumption through everyday food choices.

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 may contribute to cardiovascular health. 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 certain groups in the UK population have magnesium intakes below the Reference Nutrient Intake (RNI), particularly adolescents and young 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 87mg of magnesium. 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 seed kernels contain around 534mg per 100g, whilst almonds provide approximately 268mg, cashews 270mg, and Brazil nuts 376mg per 100g. A small handful (30g) of mixed nuts can contribute 70-90mg 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 180g portion of cooked brown rice provides about 86mg of magnesium, whilst a 40g serving of dry porridge oats contains approximately 55mg.

Legumes including black beans, chickpeas, lentils, and kidney beans are both affordable and magnesium-rich. A 200g serving of cooked black beans provides around 120mg. Dark chocolate (70% cocoa or higher) contains approximately 228mg per 100g, though a typical 30g portion provides about 68mg and should be consumed in moderation due to its calorie and sugar content.

Fish such as mackerel, salmon, and halibut contribute useful 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 significantly between products.

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 women do not require additional magnesium beyond the standard female RNI, as the body adapts to increase absorption efficiency during pregnancy. However, breastfeeding women have slightly increased needs, with recommendations suggesting an additional 50mg daily, bringing the total to approximately 320mg per day to account for magnesium secreted in breast milk.

Children's requirements increase progressively with age. Infants aged 0-3 months require approximately 55mg daily, rising to 60mg for those aged 4-6 months, 75mg for 7-9 months, and 80mg for 10-12 months. Toddlers aged 1-3 years need around 85mg, whilst children aged 4-6 years require 120mg, and those aged 7-10 years need 200mg. As children enter adolescence, requirements increase further: boys and girls aged 11-14 years need 280mg. Teenagers aged 15-18 years approach adult levels, with boys requiring 300mg and girls 300mg daily.

It is worth noting that 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 (particularly proton pump inhibitors or diuretics), and older adults may have increased magnesium requirements or reduced absorption efficiency. People with chronic kidney disease should avoid magnesium supplements unless advised by their healthcare provider. If you regularly use magnesium-containing laxatives or antacids, discuss this with your GP before considering additional magnesium.

Whilst magnesium from food sources is safe, supplements can cause diarrhoea and other side effects. According to NHS guidance, taking 400mg or less of supplemental magnesium daily is unlikely to cause harm in most adults with normal kidney function. If you have concerns about your magnesium status, discussing this with your GP or a registered dietitian is advisable rather than self-supplementing.

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 or attributed to other causes. Early signs of inadequate magnesium intake may include fatigue, weakness, and reduced appetite. Some individuals report experiencing muscle cramps, particularly in the legs at night, or muscle twitches and spasms. Whilst there is no official link establishing muscle cramps as exclusively caused by magnesium deficiency, the mineral's role in muscle function means inadequate levels may contribute to these symptoms.

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 evidence remains evolving and other factors invariably play significant roles.

More pronounced deficiency can affect cardiovascular function. Abnormal heart rhythms (arrhythmias) may develop in severe cases, as magnesium is essential for maintaining normal electrical activity in cardiac tissue. Blood pressure regulation may also be affected, though hypertension has multiple contributing factors.

Certain groups face higher risk of inadequate magnesium intake. Older adults often have reduced dietary intake and decreased intestinal absorption. Individuals with gastrointestinal conditions such as Crohn's disease, coeliac disease, or chronic diarrhoea may have impaired absorption. Type 2 diabetes can increase urinary magnesium loss, and long-term use of proton pump inhibitors or certain diuretics may affect magnesium levels.

When to seek medical advice: If you experience persistent muscle cramps, unexplained fatigue, heart palpitations, or numbness and tingling, contact your GP. Blood tests can assess magnesium levels, though serum magnesium may not always reflect total body stores accurately, and interpretation should be clinical. Your GP may need to repeat testing if clinical suspicion persists despite normal initial results. Seek urgent medical attention (999/A&E) for new or worsening palpitations, fainting episodes, seizures, or severe muscle weakness. Never self-diagnose deficiency or begin supplementation without professional guidance, as excessive magnesium intake can cause adverse effects including diarrhoea and, in extreme cases, more serious complications.

If you suspect side effects from any medicines, vaccines, or herbal products, report them through the MHRA Yellow Card scheme.

Tips for Increasing Magnesium Through Your Diet

Optimising your magnesium intake through dietary sources is both achievable and sustainable with practical strategies. Start with breakfast by choosing wholegrain options such as porridge oats (40g dry oats provides approximately 55mg magnesium) topped with sliced banana (27mg per medium banana), a tablespoon of ground flaxseeds (40mg per tablespoon), and a handful of chopped almonds (80mg per 30g). This combination provides a substantial magnesium boost alongside fibre and other essential nutrients. Alternatively, two slices of wholemeal toast with almond butter offers around 60mg of magnesium.

Incorporate leafy greens daily by adding spinach or kale to various meals. A 100g portion of cooked spinach provides approximately 87mg of magnesium. Wilt spinach into pasta dishes, curries, or omelettes. Include rocket or watercress in sandwiches and salads. A side portion of steamed greens with your evening meal significantly contributes to daily magnesium intake whilst providing vitamins A, C, and K.

Make nuts and seeds accessible by keeping small portions readily available. Pre-portion 30g servings into small containers for convenient snacking (providing 70-90mg magnesium depending on the mix). Sprinkle pumpkin seeds over soups, salads, or roasted vegetables. Add chia seeds to yoghurt, smoothies, or use them to make chia pudding. Nut butters spread on fruit or wholegrain crackers provide both satisfaction and nutritional value.

Choose whole grains over refined alternatives whenever possible. Replace white rice with brown rice (a 180g portion provides about 86mg magnesium), quinoa, or bulgur wheat. Select wholemeal or granary bread instead of white varieties. Experiment with whole grain pasta or try ancient grains like spelt or freekeh for variety.

Include legumes regularly in your meal planning. Add chickpeas to salads, make bean-based soups or stews, or prepare hummus as a nutritious dip. A 200g portion of cooked lentils provides approximately 72mg of magnesium. Lentils cook quickly and work well in curries, bolognese sauce, or as a side dish. Canned varieties offer convenience without compromising magnesium content—simply rinse before use.

Cooking methods matter: Boiling vegetables in large amounts of water can leach magnesium into the cooking liquid. Steaming, roasting, or stir-frying helps retain mineral content. When boiling is necessary, use minimal water and consider incorporating the cooking liquid into soups or sauces.

Stay hydrated with magnesium-containing water: Some mineral waters naturally contain magnesium, with content listed in mg/L on the label. Tap water in hard water areas also contributes small amounts of magnesium to daily intake.

Plan balanced meals that combine multiple magnesium sources. A dinner of grilled salmon with quinoa and roasted vegetables topped with pumpkin seeds provides approximately 150-200mg magnesium from several food groups whilst ensuring dietary variety. Gradually introducing these changes makes them more sustainable than dramatic dietary overhauls.

Frequently Asked Questions