– Fat-soluble vitamins (vitamin A, vitamin D, vitamin E and vitamin K) are better absorbed with full stomach. Take supplements such as daily multivitamins, vitamin E, calcium + vitamin D and vitamin D + vitamin K after meal.
– Absorption of water-soluble vitamins such as group B vitamins and vitamin C are not affected with food. For this reason, these vitamins can be taken regardless of the time of taking foods (on an empty stomach or after taking food).
– Note that taking a medicine on an empty stomach means taking it one hour before or two hours after a meal, and taking it on a full stomach means taking it between or immediately after a meal.
– Minerals such as calcium and magnesium and trace elements such as zinc, manganese, etc. require an acidic environment for absorption, so it is better to take them after meals when stomach acid secretion increases. Take these supplement at least 2 hours apart from taking antacids such as AlMg suspension. Notice that the absorption of these minerals significantly decreases in patients taking acid suppressant drugs such as omeprazole, pantoprazole and famotidine.
– The salt form of minerals may affect their absorption, for example, magnesium citrate has better absorption compared to magnesium oxide or magnesium carbonate. Calcium citrate is also better absorbed than calcium carbonate. Citrate salts of these minerals are more suitable for patients who take acid suppressant medications.
– The prevalence of gastrointestinal side effects is important in deciding when to take a supplement. For example, GI adverse effects are common with zinc and it is usually recommended to take zinc supplements after meals. Gastrointestinal adverse effects are also common with iron compounds, but on the other hand, food reduces iron absorption. For this reason, it may be recommended to take iron supplements on an empty stomach, and in case of digestive adverse effects, it is advisable to take them after meals. But in any case, iron supplements should be taken at least two hours apart from tea, dairy products and eggs, because they reduce iron absorption significantly.
– Some medications reduce absorption of metal ions. For example, ciprofloxacin, tetracycline and related compounds reduce the absorption of minerals and iron.
– If you get minerals through taking different products, put at least 2 hours between them, because they may compete with each other in absorption. (For example, put at least 2 hours between taking supplements containing zinc, calcium, magnesium or iron)
– Supplements that are similar in structure to amino acids and proteins are better to be used between meals so that they do not compete with proteins in food for absorption (supplements such as arginine).
– In general, supplements that food does not affect their absorption (for example, supplements containing glucosamine) are better to be used after meals in order to reduce the possibility of digestive adverse effects.
– Some supplements improve each other’s absorption. For example, taking vitamin C with iron enhances iron absorption, and therefore vitamin C could be used with iron supplements for better absorption of iron.
– Sometimes it is necessary to consider the time of taking supplements according to their clinical use. For example, in case of using arginine for erectile dysfunction it should be taken one hour before intercourse. Arginine for improving athletic performance is better to be taken one hour before exercise.
– If you use several supplements or medicines, always consult your pharmacist or doctor to to be informed about the optimal time of taking your medicines or supplements.