5 Supplements to Avoid Combining

Medically reviewed by Femi Aremu, PharmD

• Some supplements can negatively affect each other’s absorption or efficacy when consumed together.

• Combining supplements that have similar effects may increase the risk of adverse reactions or health issues.

• To ensure safety, it’s best to space out doses, avoid excessive amounts, and consult a healthcare professional before mixing supplements.

While supplements can play a vital role in enhancing your health, it’s essential to be mindful of their timing and combinations. Certain pairings can diminish absorption or lead to unwanted side effects.

1. Calcium and Iron

What happens: Taking calcium alongside iron is not recommended. “Both calcium and zinc can inhibit the absorption of iron minerals because they compete for absorption in the intestines,” explains Jennifer Warren, MD, DABOM, DABFM, medical director at Mochi Health. “This is particularly important for individuals with iron deficiency who require additional iron to combat anemia,” she adds.

Why it matters: Since iron and calcium compete for absorption in the digestive system, taking them simultaneously can diminish their effectiveness, reducing the nutrients your body actually absorbs.

What to do instead: “To maximize absorption, take iron independently in the morning with either water or citrus juice, as vitamin C can enhance iron absorption. Avoid consuming other mineral supplements for at least two hours,” recommends Warren. If iron supplements cause nausea on an empty stomach, they can be taken with a small amount of food. Likewise, calcium should also be taken alone to optimize absorption.

2. Calcium and Zinc

What happens: Similar to iron, calcium competes for absorption with other minerals, such as zinc. “Calcium and zinc will vie for absorption in the gut, so taking them together can diminish the amount absorbed of each,” states C. Vivek Lal, M.D., director of clinical innovation at the Heersink Institute of Biomedical Innovation at the University of Alabama at Birmingham.

Why it matters: “Zinc is crucial for immune function and healing, while calcium helps meet dietary requirements for bone health,” explains Lal. “Suboptimal absorption resulting from nutrient competition can hinder these benefits,” he indicates.

What to do instead: “A practical approach is to consume calcium supplements during meals and take zinc at other times when not paired with calcium-rich foods or supplements,” advises Lal. It’s worth noting that some forms of calcium, like calcium citrate, can be taken with or without food, while others, such as calcium carbonate, should be taken with meals.

3. Zinc and Copper

What happens: Copper and zinc compete for absorption in the small intestine. “These minerals share similar transporters in their absorption pathways, leading to competition,” explains Helen Tieu, RD.

Why it matters: While both copper and zinc compete for absorption, issues usually arise when excessively high doses of zinc are consumed. Research indicates that long-term intake of 60 milligrams or more of zinc daily can impair copper absorption, potentially leading to deficiencies that may cause health issues like anemia and muscle weakness. The Tolerable Upper Intake Level (UL) for zinc is set at 40 milligrams per day for adults.

What to do instead: “Space out doses of these minerals throughout the day or opt for a balanced multivitamin that includes lower amounts of zinc and copper,” suggests Tieu.

4. Fish Oil and Ginkgo Biloba

What happens: Platelets are tiny blood cells that enable your blood to clot and minimize bleeding. “Ginkgo biloba and high-dose fish oil can both inhibit platelet function, making it riskier to take them together due to increased bleeding potential,” explains Lal. This is particularly important for individuals on blood-thinning medications like Warfarin. “Similar caution applies to other blood-thinning supplements such as garlic, ginger, turmeric, and ginseng,” he adds.

Why it matters: Consuming high doses of blood-thinning supplements can pose significant risks, especially for those already using anticoagulants. It’s also unwise to take blood thinners prior to scheduled surgeries, as this heightens the risk of excessive bleeding.

What to do instead: To ensure safety, Lal suggests steering clear of combining these supplements, considering lower dosages, and discussing your regimen with your physician, particularly before any surgical procedures.

5. Activated Charcoal with Any Nutrient

What happens: Activated charcoal is a well-known natural remedy for digestive issues like bloating and for detoxifying the body. However, it is inadvisable to take activated charcoal with vitamins and minerals. “Activated charcoal binds to these substances, impairing their absorption,” warns Lal.

Why it matters: Extended usage of activated charcoal can prevent the absorption of essential nutrients, leading to deficiencies and potential health concerns. It can also interfere with the absorption of medications, diminishing their efficacy, which can pose health risks.

What to do instead: Lal recommends using activated charcoal in short, directed doses, ensuring it is taken separately from all medications and supplements for a span of 2 to 4 hours.

Why Supplement Combinations Matter

While dietary supplements may appear harmless, improper combinations or excessive dosages can lead to diminished nutrient absorption and serious side effects.

“Considering supplement interactions is vital since many share absorption pathways and affect the enzymes responsible for metabolizing and clearing medications,” explains Warren. “These interactions could lead to severe consequences, including medication ineffectiveness, nutritional deficiencies, and adverse effects.”

If you’re uncertain about specific supplement combinations or have queries about safety, it’s highly recommended to consult your healthcare provider.

How to Take Supplements Safely

Here are some practical guidelines to help you ensure safe supplement use:

• Space them out: Take competing nutrients several hours apart. For instance, consume iron in the morning and calcium later in the day.

• Avoid large doses: Unless directed by a healthcare professional, it’s safest to remain below the established upper limits (ULs) for vitamins and minerals to prevent excessive intake, which might deplete other essential nutrients in certain cases.

• Pair wisely: Some supplement combinations promote absorption, such as vitamin C and iron, while others, like calcium and iron, hinder it.

• Consult with your healthcare provider: If you have any doubts or need guidance regarding supplements, consider discussing your concerns with a trusted healthcare professional.

For more information, please refer to the original article on Health.