You have probably found yourself in this situation frequently.  You are at the food market, trying to put together a healthy diet for a week, which requires you to decide just what you’ll be in the mood for a couple of days from now.

The beans look good. There’s a special on lamb chops. And the strawberries are calling your name. Exactly how much, and of what, do you need to buy – and eventually consume – to meet your nutrient requirements?

Start with vitamin D, the sunshine vitamin. The evidence is amassing that we need it not just for strong bones but for durable minds, healthy hearts, and to ward off many types of cancer. But where do we get it (besides sunshine)? And (this is the big question) exactly how are we supposed to know what the recommended daily allowance – expressed by the government and nutritionists in international units, anywhere from 200 to 600 of them – looks like in terms of actual food?

And that’s just one of 13 vitamins, 14 minerals, several types of fiber, and countless antioxidants and phytochemicals that help maintain health. How do you balance all of those needs in real food?

Your best bet is to think: color. The natural color of a food can be a reliable indicator of the vitamins, minerals, and other nutrients it supplies.

For example, dark green veggies such as broccoli, spinach, and sugar snap peas are high in vitamin C.

Red, yellow, and orange fruits and vegetables such as carrots, sweet peppers, and sweet potatoes are known for their high beta carotene, or vitamin A, content, but they can also be rich in vitamin C.

White fruits and veggies, like mushrooms, potatoes, and bananas, supply B vitamins and many minerals, while white dairy products – milk, yogurt, cheese – provide ample amounts of calcium (and are usually fortified with vitamin D).

Purplish-blue foods, like grapes and blueberries, are best known for their anticancer and heart-helping antioxidants. But like most other fruits and vegetables, they’re also high in vitamin C and fiber.

Brown foods, in the form of grains, nuts, and seeds, supply vitamins E and B, which include folic acid. Brown and white foods like meat, fish, poultry, tofu, and legumes stand out as defining sources of protein and minerals like iron and zinc.

The more colors you toss into your shopping cart, the better chance you have of meeting all your nutritional needs. Choose a variety of superstars from every food group – mangoes and blueberries from the fruit group; spinach, broccoli, and potatoes from vegetables; oatmeal, wheat germ, and a multigrain roll from the grains; skim milk and yogurt from dairy; salmon and lentils from the protein group – all packed into a single day.

Approach your snacks just as wisely. Instead of grabbing a handful of pretzels or chips, fill the gaps between meals nutritiously. You can nibble on berries or other fresh fruits; pick away at almonds, walnuts, or sunflower seeds; savor low-fat yogurts and cheeses; or munch on whole-grain crackers. Not all at once, of course.

“You don’t have to meet the daily requirement for every single nutrient every single day, and in fact, most people can’t,” says Susan Finn, CEO of the American Council for Fitness and Nutrition and former president of the American Dietetic Association. “Focus on choosing a wide variety of foods from every food group, every day, at every meal, include plenty of ‘superstars,’ and you’ll get the nutrients you need.”

To meet the nutritional needs of two people for a day, here’s a rough guide to what to put in your shopping basket: 1 to 11/2 pounds of meat, fish, poultry, or protein alternative like beans, tofu, or wheat gluten; one-half to 1 pound each of three or four different vegetables, including one starchy veggie such as potatoes, peas, or winter squash; two pieces of three or four different fruits, including berries; a quart of milk, two containers of yogurt, and one or two types of cheese; a high-fiber cereal such as oatmeal or raisin bran; walnuts, almonds, or sunflower seeds for snacking; a box of pasta or a bag of rice to substitute for starchy vegetables.

Bon appétit.

Content supplementation from and Psychology Today