Certain supplements should not be taken together, as this can lead to more issues than benefits.

Zinc and Calcium. They compete for absorption in the intestine, so taking them together will be less effective. To avoid this, dietitian Alyssa Simpson recommends taking zinc and calcium supplements with an interval of at least two hours.

Iron and Zinc. Iron can reduce the absorption of zinc when these two supplements are taken together, says Elizabeth Harris, MS, a certified dietitian. It is best to take these supplements with an interval of at least two hours.

Iron and Calcium. For adequate absorption in the intestine, take these supplements one after the other with a break of at least two hours.

Magnesium and Zinc. Take them at different times of the day. For example, magnesium in the evening and zinc in the morning. It is also recommended to take zinc with food, as it may cause nausea.

St. John's Wort and Serotonergic Supplements. St. John's Wort can lead to an increase in serotonin levels, so it should not be taken simultaneously with antidepressants.

Ginkgo Biloba and High Doses of Fish Oil. They thin the blood, and taking them together may increase the risk of excessive bleeding, notes dietitian Angie Coneghy. Also, be cautious with aloe, garlic, ginger, turmeric, fenugreek, and ginseng. They also thin the blood.

St. John's Wort and Ginseng. Both of these supplements increase serotonin levels. Therefore, it is not advisable to take them together.