Eating well is an essential part of a healthy life, and the older you get, the more important it becomes to make good food choices. It helps keep your body strong, your mind sharp, and your energy level up. Here's a quick guide to the types of healthy foods that should always be on your shopping list.

Fruits and vegetables. Look for the most colorful produce, says Diane Stadler, PhD, RD, a research assistant professor of medicine at Oregon Health & Science University. "The darker the red, the deeper the green, the more yellow, the more orange -- they're the foods that have function." That means they're loaded with vitamins and antioxidants. Stadler recommends blueberries, red raspberries, and dark cherries as ideal fruits, and she says you can't miss with any of the dark leafy vegetables like spinach, kale, or Swiss chard. And you can have them all year because, when it comes to nutrients, frozen is just as good as fresh.

Dairy. "This is an incredibly important food group for people as they get older," Stadler says. "Calcium needs are high and they stay high, and you can't get any other foods with as much calcium as dairy." Milk, for example, gives you nearly all the calcium you need in three 8-ounce servings. Dairy's also a great source of vitamin D -- it's essential for healthy bones, but people of a certain age are often deficient in D. Stick to low-fat or nonfat milk, yogurt, and cheese.

Whole grains. These powerhouse foods are pantry essentials. A good source of B vitamins, they are also loaded with some of the best-for-you fiber available. A recent study found the fiber in whole grains is better protection against cardiovascular disease, infections, and respiratory ailments than fiber from any other source. And whole-grain foods are much more widely available now. "There's a whole variety beyond oatmeal and whole wheat, such as quinoa, which is incredibly high in protein."

Meat. "If you choose it, choose wisely," Stadler says. Focus on lean meats such as skinless chicken and turkey breasts, which supply protein and vitamin B-12 without heart-clogging fats. "If you can see a layer of fat, it is saturated fat and associated with bad cholesterol," she says. You want to avoid that as well as gargantuan proportions. Stadler recommends visualizing a deck of cards when choosing a portion of meat. If there's more than that on your plate, she says, box it up or take it off your plate before you start to eat to avoid temptation.

Fish. Oily fish like salmon provide an excellent source of omega-3 fatty acids, which help fight the bad cholesterol that tends to build up as we get older. Stadler says just two servings of fatty fish per week are enough to meet your requirements for this healthy fat. Canned salmon is a good choice because it is often packed with some edible fish bones, adding a calcium boost. If you don't eat fish at home, order it when you go out. "That's a perfect opportunity to meet the recommendations," she says.