Incorrectly selected supplements can not only not provide the expected benefits, but also reduce the absorption of nutrients or even cause side effects. Doctors and nutritionists remind: the timing of intake and combinations matter, especially when it comes to minerals and popular "health" supplements.
Specialists, including experts from Health, draw attention to several combinations that should be avoided or taken at intervals.
Calcium and iron: competitors in the intestines
According to Jennifer Warren, MD, calcium and zinc can block iron absorption because they compete for absorption in the intestines. Therefore, it is advisable to take iron supplements separately - in the morning, with water or citrus juice, as vitamin C improves iron absorption.
The doctor advises avoiding taking iron with other supplements for at least two hours. If iron on an empty stomach causes nausea, it can be taken with a small amount of food, but still not combined with calcium.
Calcium itself is also better to consume separately from iron so as not to reduce the effectiveness of both minerals.
Calcium and zinc: less benefit when taken together
S. Vivek Lal, MD, explains that calcium and zinc also compete for absorption. Taking them together can make it harder for your body to absorb each mineral.
Zinc is important for the immune system and tissue healing, and calcium is important for bone health. Poor absorption due to competition in the gut reduces the benefits of both supplements.
The specialist advises:
– take calcium with meals;
– do not combine it with zinc in calcium-rich foods or in the same dose of supplements.
The form of calcium matters: calcium citrate can be taken regardless of meals, while calcium carbonate is better absorbed during meals.
Zinc and Copper: Risk of Copper Deficiency
Nutritionist Helen Thieu reminds us that zinc and copper have similar transport pathways in the body and compete for absorption. Taking high doses of zinc (60 mg per day or more) for a long time can impair copper absorption and reduce its levels in the blood.
Copper deficiency can lead to anemia, muscle weakness, and other health problems. For adults, the upper safe limit for zinc intake is 40 mg per day.
To avoid imbalances, the nutritionist advises dividing the intake of zinc and copper throughout the day or choosing multivitamin/mineral complexes with moderate doses of these elements.
Fish oil and ginkgo biloba: double "thinning" effect
Dr. S. Vivek Lal warns that ginkgo biloba and high doses of fish oil can suppress platelet function. When combined, they increase the risk of bleeding due to excessive blood thinning.
To reduce the risks, he advises not to take these supplements at the same time, and if necessary, to reduce the dose or alternate them in time. People who are already taking medications that affect blood clotting should be especially careful.
Activated charcoal: removes vitamins and minerals
Activated charcoal is known for its ability to bind toxins, but along with them, it also "cleans" beneficial substances. That is why it should not be combined with vitamins or mineral supplements.
According to Lal, activated charcoal binds to minerals and vitamins, dramatically reducing their absorption. This supplement, if prescribed, should be taken in short courses and be sure to separate any medications, vitamins, and minerals by 2–4 hours.
General rule: don't "mix" everything in one go
Doctors emphasize that even useful supplements can lose their effectiveness or become dangerous if taken haphazardly and combined with “everything with everything.” Before starting to take vitamins and minerals, you should:
– consult a doctor or clinical nutritionist;
– evaluate real tests, and not just focus on your well-being;
– adhere to recommended doses and dilute problematic combinations over time.
Only in this case will supplements really work for your benefit and not create hidden health risks.
