How much magnesium do you need per day?
Research suggests that the 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 to eat enough magnesium-rich foods, as a large portion of the population falls short.
Research in 243 adults estimates that you need an average of 165 mg of magnesium per day to stay in balance, meaning you absorb as much as you excrete. That works out to roughly 2.36 mg per kilogram of body weight. But there is considerable individual variation: the prediction interval runs from 113 to 237 mg per day. Age and sex made no difference in that study.
This is notably lower than the official recommendations found in most dietary guidelines. That said, it does not mean that a higher intake is harmful. A higher intake through food is associated with a lower risk of high blood pressure, cardiovascular disease, stroke and type 2 diabetes. These are associations, not proven cause and effect, but they have been found in several large analyses.
A substantial portion of the population does not even reach the official recommendation. The Western diet contains few whole grains, nuts, legumes and leafy vegetables, which are the best sources of magnesium. People who structurally consume too little, sometimes only 50 to 99 percent of their requirement, may have elevated inflammatory markers in the blood without experiencing any direct symptoms.
If you want to know whether you have a deficiency, a standard blood test is not reliable enough. The magnesium level in the blood is a poor reflection of the body's total magnesium stores. More accurate tests exist, but are rarely used in routine clinical care. The best practical step is to make sure you eat enough magnesium-rich foods, such as nuts, seeds, whole grain products and green leafy vegetables.
The estimated balance point of 165 mg per day comes from a single controlled analysis involving 243 participants and 664 measurements. The associations with chronic diseases are based on several large reviews and meta-analyses, but do not demonstrate a cause-and-effect relationship. The findings on inflammatory markers and the Western diet come from comparable observational analyses. The researchers themselves emphasise that the official recommendations may have been set too high, but that the evidence for this comes from limited datasets.
How much iron do you need per day?
For healthy adults without a deficiency, compensating for 1 to 2 mg of iron per day through a varied diet is sufficient; if you have a demonstrated deficiency or are pregnant, the requirement is much higher and it is best discussed with your doctor.
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 much vitamin D should you take per day?
For healthy adults under 75, extra vitamin D is probably not necessary, but for children, people aged 75 and older, pregnant women, and those at high risk of diabetes, supplementation is worthwhile. If you are unsure whether you belong to a risk group, it is worth discussing this with your general practitioner.
Can you take too much magnesium?
Yes, too much magnesium can be dangerous, although serious toxicity from ordinary supplements is rare in people with healthy kidneys. With kidney problems or when using intravenous magnesium, medical supervision is genuinely necessary.
Which form of magnesium is best to take?
Magnesium citrate has the strongest evidence for good absorption in humans; if you want to take a magnesium supplement, an organic form such as citrate is a reasonable choice, but pay attention to product quality as well, because it varies considerably.