Magnesium requirements by age and sex

Daily requirements across life stages

Requirements come from the UK Reference Nutrient Intake and the US Recommended Dietary Allowance with both reference points covering the needs of approximately 97.5 percent of healthy individuals.

Children and adolescents

Infants 0 to 6 months need around 55 milligrams daily. Babies 7 to 12 months need 75 milligrams. Children 1 to 3 years need 80 milligrams. Children 4 to 8 years need 130 milligrams. Children 9 to 13 years need 240 milligrams. Adolescent boys 14 to 18 years need 410 milligrams while girls of the same age need 360 milligrams. Growth-related needs are highest during adolescence.

Adult women

UK women aged 19 and over need 270 milligrams of magnesium daily. US guidance recommends 310 milligrams daily for women 19 to 30 years and 320 milligrams daily for women 31 years and over. Both reference points cover the needs of most healthy adult women. Heavy menstrual losses can slightly increase requirements in some women.

Adult men

UK men aged 19 and over need 300 milligrams daily. US guidance recommends 400 milligrams daily for men 19 to 30 years and 420 milligrams daily for men 31 years and over. The higher male requirement reflects larger body size and muscle mass on average. Both reference points cover most healthy adult men.

Pregnancy and lactation

Pregnant women need 350 to 360 milligrams daily depending on age. Lactating women need 310 to 360 milligrams daily depending on age. The additional intake supports fetal development and milk production. Most antenatal multivitamins include magnesium at appropriate amounts though dietary intake typically still matters alongside.

Athletes and active adults

Heavy training increases needs 20 to 30 percent above the standard requirement. Adults doing serious endurance or strength training typically need 350 to 450 milligrams daily depending on training volume and conditions. Adults training hard in hot conditions may need slightly more again given sweat losses.

Practical intake for your situation

Adults wanting to meet their specific requirement can do so through targeted attention to magnesium-rich foods. A few sensible habits cover most situations.

Identify your target based on age, sex and situation

Standard adult requirement is 270 milligrams for UK women and 300 milligrams for UK men. Add 30 to 60 milligrams for pregnancy. Add 60 to 100 milligrams for heavy training. Use the right number for your actual situation rather than generic guidance.

Include magnesium-rich foods consistently

Dark leafy greens, nuts, seeds, whole grains and legumes provide the foundation. A daily portion of dark greens, a handful of nuts and whole grain choices over refined hits the standard adult requirement reliably. Adults with higher needs add more of these foods or supplement modestly.

Adjust for age-related changes

Older adults aim slightly above the standard requirement at around 350 milligrams to compensate for reduced absorption. Adolescents during growth phases need particularly high intake. Children and infants need age-appropriate amounts which are met by varied family eating rather than requiring specific calculation.

Use supplementation to fill gaps

Adults whose diets fall short of their specific requirement benefit from modest supplementation. Magnesium glycinate at 200 to 300 milligrams daily fills most gaps. The supplement complements diet rather than replacing it. Most magnesium-rich foods bring other beneficial nutrients alongside.

Reassess across life stages

Requirements change with pregnancy, lactation, training phases, ageing and changing health conditions. Reassess intake periodically rather than maintaining the same approach for decades. Major life changes warrant magnesium reassessment alongside other nutritional considerations.

When to see your GP about magnesium concerns

Meeting magnesium requirements is generally safe. See your GP if any of the following apply.

• Pregnancy or breastfeeding. Use antenatal multivitamins rather than separate magnesium products.
• Children needing supplementation. GP guidance for paediatric dosing.
• Kidney disease. Specialist input regardless of age.
• Persistent symptoms despite meeting requirements. Investigate other causes.
• Multiple medications. Pharmacist review for interactions.

Magnesium requirements vary across life stages and situations. Knowing your specific target rather than relying on generic guidance helps assess whether your intake actually meets your needs. Most adults can meet requirements through dietary attention with modest supplementation if needed. Specific situations including pregnancy, paediatric supplementation and kidney disease need medical guidance.

More on magnesium intake

Age-specific needs connect to broader topics. How much magnesium do adults need per day covers the adult basics. Magnesium and ageing covers older adult specifics. And Dietary sources covers practical food choices.