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- Some supplements work better when taken together.
- Some supplement combos help improve absorption. For example, vitamin D allows the gut to absorb calcium. And vitamin C helps the body absorb iron.
- Other supplements that may work better together include vitamin D and magnesium, as well as omega-3 and vitamin E.
You’ve probably heard that some supplements shouldn’t be mixed—but on the flip side, certain vitamin and mineral combinations actually work better in tandem. Dietitians say these nutrient pairings are worth considering for their added benefits.
1. Vitamin D and Calcium
For the approximately 10 million Americans with osteoporosis, bone health is naturally top of mind. If you’re looking to strengthen your skeleton, consider combining vitamin D and calcium.
“Vitamin D and calcium work synergistically to support bone health and prevent osteoporosis,” Julie Pace, RDN, of Core Nutrition Health & Wellness, told Health. “Vitamin D is essential for calcium absorption in the gut. Without it, your body can’t use calcium effectively,” she explained.
A 2019 study found that taking both vitamin D and calcium was more effective for preventing hip fractures in people at risk than taking vitamin D alone.
2. Vitamin C and Iron
Iron- and vitamin C-rich foods, like leafy greens and citrus fruits, don’t just taste good together—they’re also nutrient teammates.
Vitamin C enhances the body’s ability to absorb nonheme, plant-based iron, Erin Jowett, MS, RD, LDN, a functional dietitian, weight-loss expert, and founder of Integrative Weight & Wellness, told Health. It “does this by increasing the acidity of the GI tract, enhancing the conversion of ferric iron to ferrous iron,” the kind that's easier to absorb.
Getting enough iron is key for numerous areas of health. Having adequate levels supports oxygen transport and muscle metabolism and helps prevent iron-deficiency anemia.
3. Zinc and Vitamin A
Zinc is well known for supporting immune defense, helping the body fight off infections like the common cold. Vitamin A also plays a key role in immune health—as well as healthy vision, cellular communication, and reproduction.
Together, these nutrients build on each other’s effectiveness, said Amanda Crowe, MS, RD, INHC, founder of Drive By Nutrition. “Zinc enables the synthesis of retinol-binding protein, which transports vitamin A from the liver to tissues, and activates enzymes that convert retinol [a form of vitamin A] to its active form,” she told Health. It’s no surprise then that some studies have found that zinc and vitamin A deficiencies often go hand in hand.
4. Omega-3s and Vitamin E
Hoping to reap the brain and heart health perks of omega-3 fatty acids? You may want to pair them with vitamin E. “Omega-3 fats are highly unsaturated and prone to oxidation; vitamin E protects these fats and cell membranes, helping preserve their anti-inflammatory and cardioprotective effects,” Crowe said.
A 2019 meta-analysis found that combining vitamin E and omega-3 supplements reduced markers of inflammation, increased total antioxidant capacity, and boosted nitric oxide—a molecule that promotes better blood flow.
Before loading up on both, keep in mind that each one affects blood clotting. As such, Crowe recommended that those taking an anticoagulant consult a provider before using high-dose supplements.
5. Selenium and Iodine
Selenium and iodine don’t always get the spotlight, but these trace minerals are critical for good health—especially when it comes to a thriving thyroid. By regulating thyroid hormones, they support metabolism, weight regulation, and mood, said Jowett.
These two thyroid-supporting minerals also happen to work in tandem. “Selenium helps convert thyroid hormone (T4) into its active form (T3), while iodine helps build it,” Jowett said. Since low levels of either mineral can slow thyroid function, taking them together may help boost your endocrine system. If you have an overactive or underactive thyroid, ask your doctor about whether this combination should be part of your treatment.
6. Vitamin D and Magnesium
Vitamin D is one of the most popular dietary supplements in the U.S., second only to multivitamins. Magnesium is also commonly taken, driven in part by reports that most people in the U.S. don’t get enough from their diets.
If you happen to be supplementing with both, you’re onto something. According to Jessica Brantley-Lopez, MBA, RDN, vitamin D helps the gut transport magnesium from food and supplements more efficiently, while magnesium increases vitamin D absorption.
“Magnesium is required for vitamin D to be converted to its active form within the body,” Brantley-Lopez told Health. A 2018 study, for example, found that magnesium supplementation improved vitamin D levels in people with little of it and reduced levels that were too high.
In short, these two nutrients create a positive feedback loop that may support bone health, mood, and immune function, said Jowett.
