Calcium and Iron
One of the most common supplement conflicts occurs between calcium and iron. Both minerals are vital for health—calcium supports bone strength, while iron is essential for oxygen transport and energy—but taking them together can backfire.
“Calcium and iron use similar absorption pathways in the intestinal tract,” explains Sather. “When both are present in the digestive system at the same time, they compete for uptake. Calcium often wins, which can block your body from properly absorbing iron.”
This can be especially concerning for people who are iron deficient, pregnant, or have higher iron needs. Over time, consistently pairing these two nutrients could make it harder to maintain healthy iron levels, potentially leading to fatigue, weakness, or other health issues.
How to Take Calcium and Iron Safely
Fortunately, there’s a simple solution. Sather recommends spacing these supplements at least two hours apart.
Iron: Take it in the morning with water or a vitamin C-rich drink like orange juice to boost absorption.Calcium: Take it later in the day, ideally with a meal, avoiding iron-rich foods at the same time.
By separating these minerals, you can ensure your body gets the full benefits of both, supporting everything from bone health to energy levels.
The bottom line
Even when supplements are meant to improve your health, timing matters. Pairing calcium and iron together may seem convenient, but it can unintentionally cancel out their benefits. Following Sather’s advice on spacing your supplements can help you get the most out of your routine—without compromising your nutrient intake.