How much iron do you need per day?
For healthy adults without a deficiency, 1 to 2 mg of iron per day through food is sufficient. When a deficiency or anaemia is confirmed, requirements are much higher; discuss that with your doctor.
Your body loses 1 to 2 mg of iron every day through the skin, the gut lining and sweat. You need to replenish this through food. Haem iron from red meat and fish is absorbed more easily than non-haem iron from legumes and leafy vegetables. Vitamin C eaten at the same meal helps the absorption of plant-based iron.
If you have a confirmed iron deficiency without anaemia and you feel tired, a supplement can help with that feeling of fatigue. Discuss with your doctor how much to take and for how long. On the label, what matters is the number of milligrams of elemental iron per tablet, for example in iron sulphate; the brand name is irrelevant.
In cases of iron-deficiency anaemia, people in research studies received up to 200 mg of elemental iron per day for 3 to 12 weeks. Only a small proportion of that is absorbed; the rest can cause gastrointestinal complaints such as constipation or nausea. Always find out why you have a deficiency before you start, and discuss this with your doctor.
If you are pregnant, your iron requirement is considerably higher. In research studies, pregnant women with iron-deficiency anaemia received up to 200 mg of elemental iron per day orally, during the third trimester and the period after delivery. Discuss this with your doctor or midwife. If you use thyroid medication or antibiotics such as ciprofloxacin, never take iron at the same time: it reduces the effectiveness of those medicines.
Do you want to take iron for your immune system or sports performance? It has been too little studied for that purpose to be recommended. The strongest evidence for immune support applies to vitamin C, vitamin D and zinc. And even with an iron deficiency without anaemia, your fitness levels are demonstrably not improved by it.
Based on PMID 33739032, 40066539, 34623079, 40603803 and 31963293. No large RCTs on daily requirements in healthy people; the 1-2 mg norm is based on loss/balance research.
How much magnesium do you need per day?
Research suggests that your body reaches balance at around 165 mg per day, but official recommendations are higher and there is considerable individual variation. In any case, make sure you get enough magnesium-rich foods, as a large part of the population falls short.
How much lithium do you need each day?
There is no official daily recommendation for lithium; scientists cite 1 mg per day as a cautious guideline, but evidence for benefits in healthy people is largely absent, so supplementation is not yet substantiated.
How much water do I really need to drink per day?
There is no magic number: for a healthy adult who is not very active, thirst is a reliable guide, with a total fluid intake of roughly 2 to 3 litres per day from all sources as a reference point. Drink more as soon as you exercise, when it is warm, or as you get older.
How many vegetables do you really need per day?
Five servings of vegetables and fruit per day offers the best protection, with non-starchy vegetables counting and juice and potatoes not. More than five servings adds nothing.
How many cups of green tea do you need per day?
Two to three cups of green tea per day is the amount at which research shows the most health benefits, though cause and effect has not been proven. Let the tea cool a little before drinking; tea that is too hot increases the risk of oesophageal cancer.
How much fibre do I need and why?
Aiming for 25 to 29 grams of fibre per day is well supported and delivers the greatest health benefit. Most people in Western countries fall well short of that, so eating more vegetables, legumes and wholegrain products is a smart step for almost everyone.