Which form of zinc is best to take?
Zinc picolinate and zinc histidine have the strongest independent evidence for good absorption, but all comparative studies are small. Avoid large portions of grains around the time of intake, as phytate substantially blocks absorption.
If you want to try zinc for better absorption, opt preferably for zinc picolinate or zinc histidine. In a study of 15 people, hair, urine and red blood cells showed a measurable increase after four weeks only with zinc picolinate; gluconate and citrate performed no better than a placebo at the same dose. Zinc histidine produced the same effect on blood concentration as a dose of zinc sulphate three times as high, in a study of 10 people.
On the label, look for 'Zinc picolinate' or 'Zinc histidine' with a clear statement of elemental zinc in mg per capsule or tablet. Zinc gluconate and zinc aspartate are also reasonable choices: gluconate is absorbed slightly better than zinc oxide, and aspartate outperformed gluconate in a small study. The brand name, the colour of the capsule and the time of intake (morning or evening) do not matter.
What does matter: do not take zinc at the same time as large portions of wholegrain cereals, maize, rice or legumes. Phytate in those foods substantially blocks the absorption of every form of zinc. Fermenting or sprouting those products reduces that effect.
Pay attention to the upper limit: the European Food Safety Authority EFSA sets 25 mg of elemental zinc per day as the maximum without medical supervision. If you consistently take more than this, your copper levels may fall, potentially leading to anaemia or nerve complaints. If you want to use zinc for a medical condition, during pregnancy or alongside medication, discuss this with your doctor.
All comparative studies are small, with 8 to 15 participants, and of short duration. The review that identifies zinc glycinate and gluconate as the best options was written by employees of a supplement manufacturer; keep that conclusion in perspective. If your dietary intake is adequate, a supplement is not worth your money.
The available comparative studies are small (n=8 to n=15 participants). No meta-analyses are available. One review has a potential conflict of interest (authors employed at supplement manufacturer Pharmavite). The findings on the phytate-inhibiting effect are the best supported, with multiple reviews confirming them.
Which form of magnesium is best to take?
Magnesium citrate has the strongest evidence for absorption into the body. Magnesium oxide, the cheapest option, demonstrably performs the worst and is best avoided.
Should you take extra copper when taking high doses of zinc?
Anyone who takes more than 25 mg of elemental zinc per day over a prolonged period runs a real risk of copper deficiency, sometimes with serious consequences. Have your blood values checked and always discuss high zinc doses with your doctor.
Which form of vitamin B12 is best to take?
The form of vitamin B12 matters less than the dose: when correcting a deficiency, what counts above all is taking enough. When there is an absorption disorder, injections are the indicated route; discuss that with your doctor.
Which type of collagen is best to take?
For the skin, hydrolysed collagen peptides (2.5 to 5 grams per day for at least 8 to 12 weeks) are the best-supported option. For knee pain, you can try UC-II (40 mg per day) or hydrolysed collagen (10 grams per day) for six months, but the only independent study found no effect.
Is too much zinc harmful?
Too much zinc is certainly harmful: as an adult, stay below 25 mg of elemental zinc per day (EFSA limit) and be cautious with high-dose zinc supplements, because even moderate over-supplementation can disrupt copper balance.
Is zinc beneficial for my immune system?
Zinc is useful for your immune system if you have a deficiency or belong to a risk group, such as older adults or severely malnourished people. For colds, up to 30 mg of elemental zinc per day may shorten symptoms, but high doses are more likely to be harmful than beneficial.