In This ArticleView AllIn This ArticleZinc & CalciumIron & ZincIron & CalciumMagnesium & ZincSt. John’s Wort & Serotonin SupplementsGinkgo Biloba & Fish OilSt. John’s Wort & GinsengThings to ConsiderHow to Know What’s Safe
In This ArticleView All
View All
In This Article
Zinc & Calcium
Iron & Zinc
Iron & Calcium
Magnesium & Zinc
St. John’s Wort & Serotonin Supplements
Ginkgo Biloba & Fish Oil
St. John’s Wort & Ginseng
Things to Consider
How to Know What’s Safe
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Photo:Eating Well/Abbey Littlejohn
Eating Well/Abbey Littlejohn
Grocery aisles are full of supplements claiming to do everything from preventing you from getting a cold to improving your mood and reducing stress. These potential benefits have made supplements much more popular over the years, with some people taking more than a handful each day. However, taking certain supplements together can cause more issues than benefits. They may counteract each other, one may hinder absorption of the other, or they may lead to undesirable health effects when taken in combination. Here are seven supplement combinations you should not take together or should be careful about combining.
7 Things You Should Look for When Buying a Supplement, According to Dietitians
1. Zinc and Calcium
“Zinc and calcium compete for absorption in the gut, so taking them together can limit the effectiveness of both,” saysAlyssa Simpson, RDN, CGN, CLT, a digestive health dietitian.Zincis often used to support your immune health or wound healing, and calcium is used to fill dietary gaps that could harm your bone health.Yet, they probably won’t have these desired benefits if your body can’t absorb them well. To avoid this, Simpson recommends taking zinc and calcium supplements at least two hours apart.
2. Iron and Zinc
Iron can reduce the absorption of zinc when these supplements are taken together!," saysElizabeth Harris, M.S., RDN.
In particular, iron supplements with 25 milligrams of iron or more could be problematic for zinc levels. Although high doses of iron are very common when treating iron deficiency, they can reduce zinc absorption and total plasma zinc concentrations.To avoid this, taking zinc and iron supplements at least two hours apart is best.
3. Iron and Calcium
The 7 Best Iron Supplements, According to Dietitians
4. Magnesium and Zinc
“Magnesium and zinc compete for absorption in the intestines, meaning taking high doses of both at the same time can reduce how much your body absorbs each mineral,” says Hernandez. This is particularly true for very high doses of zinc (upward of 140 mg per day), which far exceeds the tolerable upper intake level of 40 mg for adults.Still, your health care provider may advise that you space these two supplements out just in case.
“Take magnesium and zinc supplements at different times of the day, such as magnesium in the evening and zinc in the morning. I recommend taking zinc with food as it has a tendency to cause nausea,” recommends Hernandez. And since magnesium glycinate (a type of magnesium)can help support relaxation and sleep, it’s a great option to take at night.
5. St. John’s Wort and Serotonergic Supplements
St. John’s wort is anherbal supplementoften used to help manage depression, although research is still mixed on its efficacy. That said, it may raise serotonin levels, so you should not take it in combination with antidepressant medications, as this could lead to a life-threatening increase in serotonin levels.
There are also risks of taking St. John’s wort with serotonin-boosting supplements. “Combining St. John’s wort with serotonin-boosting supplements like 5-HTP or SAMe can elevate serotonin levels too much, potentially leading to symptoms like restlessness and confusion,” says Simpson. The solution? “Stick to one serotonin-supporting supplement at a time,” she says. Before starting any of these supplements, we suggest speaking with your health care provider for individualized guidance.
6. Ginkgo Biloba and High-Dose Fish Oil
“Both ginkgo biloba and high-dose fish oil thin the blood and, when combined, they can increase the risk of excessive bleeding,” says Simpson. This is especially true if you’re also taking a blood-thinning medication like warfarin, saysAngie Konegni, M.S., RD, CSR, LD.
Other potentially blood-thinning supplements to be careful about taking together are aloe, garlic, ginger, turmeric, fenugreek and ginseng, among others.If you’re taking any of these supplements in combination, “consider alternating or lowering the doses to avoid stacking their effects,” recommends Simpson.
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7. St. John’s Wort and Ginseng
What to Consider If You Take These Supplements
If you’re taking any of the above supplements, speak with your health care provider before adding a new one to avoid harmful interactions. If you’ve already been taking a supplement combination that could be harmful or hinder proper absorption, reach out to your health care provider so they can advise you on how to proceed. They may simply recommend that you start taking them a few hours apart.
Also, keep in mind that it’s more likely that you’ll encounter issues if you’re taking high-dose supplements. A health care provider can advise you on the appropriate dosage for meeting your nutrient or health needs without going overboard and increasing the risk of adverse effects.
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How to Know What Supplement Combinations Are Safe
Before starting a new supplement, it’s best to speak with a health care provider to ensure it’s safe for you and get guidance on an appropriate dosage. Make sure to share all the supplements and medications you’re taking so your health care provider can let you know whether there are any supplement or drug interactions to be aware of. This is the best way to ensure your unique combination of supplements is safe to take.
The Bottom Line
Whenever possible, prioritize food over supplements. Food-food interactions are much less common, and foods contain a whole host of beneficial nutrients that work together to support your health. If you need to take any of the above supplements, speak with a health care provider for individualized guidance so you don’t accidentally pair supplements that can interact with one another.
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SourcesEatingWell uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable and trustworthy.National Institutes of Health, Office of Dietary Supplements. Fact Sheet for Health Professionals.Zinc.National Institutes of Health, Office of Dietary Supplements. Fact Sheet for Health Professionals.Calcium.National Institutes of Health, Office of Dietary Supplements. Fact Sheet for Health Professionals.Iron.National Center for Complementary and Integrative Health.St. John’s Wort and Depression: In Depth.Abebe W.Review of herbal medications with the potential to cause bleeding: dental implications, and risk prediction and prevention avenues.EPMA J. 2019;10(1):51-64. doi:10.1007/s13167-018-0158-2
Sources
EatingWell uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable and trustworthy.National Institutes of Health, Office of Dietary Supplements. Fact Sheet for Health Professionals.Zinc.National Institutes of Health, Office of Dietary Supplements. Fact Sheet for Health Professionals.Calcium.National Institutes of Health, Office of Dietary Supplements. Fact Sheet for Health Professionals.Iron.National Center for Complementary and Integrative Health.St. John’s Wort and Depression: In Depth.Abebe W.Review of herbal medications with the potential to cause bleeding: dental implications, and risk prediction and prevention avenues.EPMA J. 2019;10(1):51-64. doi:10.1007/s13167-018-0158-2
EatingWell uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable and trustworthy.
National Institutes of Health, Office of Dietary Supplements. Fact Sheet for Health Professionals.Zinc.National Institutes of Health, Office of Dietary Supplements. Fact Sheet for Health Professionals.Calcium.National Institutes of Health, Office of Dietary Supplements. Fact Sheet for Health Professionals.Iron.National Center for Complementary and Integrative Health.St. John’s Wort and Depression: In Depth.Abebe W.Review of herbal medications with the potential to cause bleeding: dental implications, and risk prediction and prevention avenues.EPMA J. 2019;10(1):51-64. doi:10.1007/s13167-018-0158-2
National Institutes of Health, Office of Dietary Supplements. Fact Sheet for Health Professionals.Zinc.
National Institutes of Health, Office of Dietary Supplements. Fact Sheet for Health Professionals.Calcium.
National Institutes of Health, Office of Dietary Supplements. Fact Sheet for Health Professionals.Iron.
National Center for Complementary and Integrative Health.St. John’s Wort and Depression: In Depth.
Abebe W.Review of herbal medications with the potential to cause bleeding: dental implications, and risk prediction and prevention avenues.EPMA J. 2019;10(1):51-64. doi:10.1007/s13167-018-0158-2
