How much of this vitamin, mineral or supplement do I need per day?

Adults 19 to 50 need 1,000 mg. It rises to 1,200 mg for women from 51 and everyone from 71, and teenagers aged 9 to 18 need 1,300 mg. The tolerable upper intake level is 2,500 mg up to age 50 and 2,000 mg after, and calcium is absorbed best in doses of 500 mg or less at a time.

Adult men and post-menopausal women need 8 mg a day. Menstruating women need 18 mg, pregnancy needs 27 mg and lactation 9 mg. The upper limit is 45 mg for adults. Vegetarians and vegans need roughly 1.8 times these figures, because non-heme iron from plants absorbs far less efficiently.

Men need 400 mg from 19 to 30 and 420 mg after; women need 310 mg then 320 mg. The catch is the upper limit: 350 mg a day applies to supplemental magnesium only. Magnesium from food carries no limit, because the kidneys clear the excess without trouble.

The RDA is only 2.4 mcg, but oral absorption is the problem, not the requirement. Intrinsic-factor absorption saturates at a couple of micrograms per dose, and everything above that relies on passive diffusion at about 1% efficiency. So the practical schedules are 25 to 100 mcg spread daily, 250 mcg once a day, or 2,000 mcg once a week — 500 mcg daily from age 65.

No. Because absorption per dose is capped, a single monthly dose leaves most of the month uncovered no matter how large it is. Monthly dosing works by injection, which bypasses absorption entirely, but not orally. Switch to daily or weekly.

The RDA is 600 IU a day from age 1 to 70 and 800 IU after, with a 4,000 IU upper limit for adults. Sun can supply it, but how much depends on your skin type, latitude, season and age — and above roughly 37° latitude, winter sunlight produces essentially none regardless of how long you stay outside.

Multiply the total oil per capsule by the EPA + DHA concentration. A 1,000 mg capsule at 30% delivers 300 mg of EPA plus DHA; at 18% it delivers 180 mg. Standard fish oil runs 18 to 30%. The AHA general range is 250 to 500 mg a day, so a weak capsule may need two or three to reach the minimum.

220 mcg a day, up from 150 mcg as a non-pregnant adult, and 290 mcg while breastfeeding. That is about 7 g of iodized salt a day at 30 mcg per gram, which is more salt than most sodium guidance allows — which is why a prenatal supplement containing iodine is the usual route.

Either 0.3 g per kg of bodyweight a day split into four doses for 5 to 7 days, then 3 to 5 g a day to maintain — or skip loading entirely and take a flat 5 g from day one, reaching the same saturation in 3 to 4 weeks. Monohydrate is the only form with the evidence behind it.

However many close the gap between your protein target and what your food already provides. At the ISSN rates that target is 1.6 to 2.2 g per kg for building muscle, and if you eat 100 g from food and need 140 g, that is two 25 g scoops. If you need more than three scoops a day, the food side of the equation is the thing to fix.

400 mg a day for healthy adults — roughly four 8 oz cups of brewed coffee. In pregnancy it is 200 mg, and for adolescents a conservative 100 mg. By weight the figure is about 6 mg per kg, capped at 400. Bear in mind that a large coffee-shop brew can carry 300 mg by itself.

Adults typically take 5 to 20 billion CFU a day, adolescents the same, children 4 to 12 about 5 to 10 billion, toddlers 2 to 5 billion and infants under a billion. But CFU count is the least important thing on the label: the strain, and whether that specific strain has evidence for what you want it to do, matters far more.