When you think about vitamins, it’s easy to imagine them as solo players, each doing one specific job. You might picture vitamin A for your eyes, vitamin C for your immune system, and vitamin K for your blood clotting. That’s true, but it’s only half the story. In your body, these three vitamins don’t just work alone—they work together in ways that make each one more effective. Understanding that teamwork can help you make better food choices and get more out of every bite.

Vitamin A is famous for supporting vision, especially in low light. But it also plays a major role in keeping your skin and the linings of your respiratory and digestive tracts healthy. Those linings are your first line of defense against germs, so vitamin A is basically your body’s bouncer. Vitamin C, meanwhile, is a water-soluble antioxidant that protects your cells from damage caused by free radicals. It also helps your body make collagen, a protein that holds your skin, muscles, and blood vessels together. Vitamin K is often overlooked, but it’s essential for activating proteins that help your blood clot when you get a cut. More recently, researchers have found it’s also critical for directing calcium into your bones and teeth instead of letting it build up in your arteries.

Now here’s where the teamwork comes in. Vitamin C helps regenerate vitamin E, another antioxidant, but it also indirectly supports vitamin A. When your body uses vitamin A to protect your cells, that vitamin can get oxidized and become less effective. Vitamin C steps in to help recycle it, keeping your vitamin A supply working longer. At the same time, vitamin A supports the health of your mucous membranes, which are often the first place vitamin C is needed to fight off infections. So one helps the other stay ready.

Vitamin K and vitamin A also partner up, particularly when it comes to your bones. Vitamin K activates a protein called osteocalcin, which acts like a magnet for calcium. Vitamin A helps regulate the cells that build and break down bone tissue. If you get too much vitamin A from supplements, it can interfere with vitamin K’s work and cause calcium to end up in the wrong places. But when you get them from food in balanced amounts, they support each other nicely. And vitamin C ties into this too because it’s required for the production of collagen, which forms the flexible framework where calcium and other minerals attach to build strong bones. Without enough vitamin C, your bones become brittle even if you get plenty of calcium and vitamin K.

For your heart, this trio also matters. Vitamin K helps keep calcium out of your artery walls by activating a protein called matrix Gla protein. Vitamin C protects the inner lining of your blood vessels from oxidative stress, and vitamin A helps maintain that lining as well. When all three are at good levels, your cardiovascular system is better equipped to stay clear and flexible. That’s a much bigger deal than any single vitamin working alone.

So how can an average American adult put this into practice without obsessing over every meal? Focus on whole foods that naturally combine these vitamins. Leafy greens like kale and spinach are stars because they contain vitamin A in the form of beta-carotene, along with a solid dose of vitamin K and a bit of vitamin C. Add some bell peppers or broccoli for a vitamin C boost, and you’ve got a simple salad that covers all three. Sweet potatoes are packed with vitamin A, while a side of sauerkraut or a handful of strawberries handles vitamin C. For vitamin K, fermented foods like natto or even sauerkraut provide it in a highly absorbable form, and so do collard greens and Swiss chard.

One thing to keep in mind is that these vitamins come in different forms. Vitamin A from animal sources like liver or eggs is preformed, while plant sources give you carotenoids that your body converts as needed. Vitamin C is water-soluble, so you need it regularly, but your body can store it to some extent. Vitamin K is fat-soluble, meaning you absorb it better when you eat it with some fat, like a drizzle of olive oil on your greens. That’s why a simple salad dressing isn’t just tasty—it’s a smart way to help your body use the nutrients.

None of this means you need to become a nutrition scientist. It just means that when you choose colorful vegetables, leafy greens, and a little healthy fat, you’re giving your body the raw materials for some impressive teamwork. Instead of thinking about vitamins as isolated pills, think of them as a crew that needs each other to do the job right. Whether it’s keeping your vision sharp, your bones sturdy, or your blood vessels clear, vitamins A, C, and K work best when they work together. And that’s a lesson you can apply at your very next meal.