Fiber-fortified soy milk. Cereal enriched with probiotics. Omega-3-fortified juice. You’ve likely seen these labels and more popping up on kids foods throughout the grocery store. It’s not empty hype; when part of a balanced diet, nutritious add-ins are a simple way to ensure your child is well nourished.

“It’s always best to get your nutrients from whole foods,” says Ellie Krieger, RD, author of So Easy: Luscious, Healthy Recipes for Every Day of the Week (Wiley, 2009), and host of Food Network’s Healthy Appetite. “That said, there are circumstances where kids need supplemental nutrients. If they don’t eat calcium-rich foods, for example, calcium-fortified juice is a great choice.” Boosting foods with nutrients is nothing new; bread and cereals have long been enriched with B vitamins to replace nutrients lost during processing, and since the 1930s vitamin D has been added to milk to enhance calcium absorption. But recently, the “functional foods” approach (adding large amounts of nutrients to foods that don’t naturally contain them) has skyrocketed: In 2008, sales of kids functional foods totaled more than $7.7 billion and accounted for 76 percent of all the healthy kids products sold, according to Nutrition Business Journal.

If you do buy fortified foods, stay away from gussied-up junk fare, like diet soda with added vitamins and minerals or sugary granola bars with extra fiber. Also, keep track of how much of a nutrient your child is taking in. “If your child eats calcium-fortified cereal and calcium-fortified juice for breakfast, with calcium-fortified snack bars, plus milk and cheese, he or she may be getting too much,” says Krieger.

Which nutrients are worth looking for in kids foods, and how much does your child need? Here’s what you should know about these supercharged ingredients.

Omega-3 fats

Kids need these essential fatty acids for brain development, Krieger says. Omega-3s also improve learning and behavior, prevent and treat bipolar disorders in children, and relieve asthma. In one study, omega-3 supplements, along with zinc and vitamin C, significantly lowered inflammation and other asthma symptoms. Unless your child eats lots of salmon and sardines, he or she may not get enough. Processed meats—high in unhealthy fats that hamper the body’s ability to uptake omega-3s—may also lead to omega-3 deficiency, says Susan Levin, RD, communications director for the Physicians Committee for Responsible Medicine. How much kids need: Kids 8 and younger, 900 mg per day; ages 9 to 13, up to 1,200 mg per day; 14 and older, up to 1,600 mg per day. Find them in: Spectrum Omega-3 Mayonnaise, Silk Soymilk, Organic Valley Omega-3-Enriched brown eggs.

Probiotics

If your child uses antibiotics, suffers a bout of diarrhea, or eats a low-fiber, high-sugar diet—all of which deplete probiotics, also called beneficial bacteria or gut flora—he or she may need to supplement. Essential to healthy digestion, probiotics also enhance immune response, inhibit allergic reactions, and dramatically reduce childhood eczema. Kombucha and yogurt with active live cultures are excellent food sources. Look for low-sugar yogurt (or other probiotic products) because sugar can counteract probiotics’ positive effects. How much kids need: At least 5 billion to 10 billion CFUs per day. Find them in: Naked Juice Probiotic Smoothies, Kashi Vive cereal

Fiber

Found naturally in whole vegetables, fruits, and grains, fiber is important for digestion and elimination, but kids (and adults) rarely get enough, says Levin. A recent national survey showed that most children ages 2 to 5 didn’t eat even close to the recommended amount of fiber. Fiber also lowers type 2 diabetes risk and may help prevent obesity. How much kids need: 14–28 grams daily. Find it in: Silk Soymilk Plus Fiber, Bob’s Red Mill Organic High Fiber Hot Cereal, Gnu Foods Flavor & Fiber Bar.

Calcium

This mineral is abundant in dairy products and most leafy greens. It’s critical for bone and tooth health, and may also play a role in weight management. But studies indicate that most kids still don’t get enough calcium; in one study, more than half of girls and nearly half of boys ages 6 to 11 missed the recommended target amount. Kids who don’t like dairy products, are lactose intolerant or allergic to dairy, who don’t eat leafy greens, or who follow a vegan diet may benefit from calcium-fortified foods. How much kids need: Ages 4 to 10, 800 mg daily; adolescents, 800–1,200 mg daily. Find it in: Rice Dream Rice Drink Enriched, Tree Ripe Orange Juice Boxes with calcium.

Vitamin D

Vitamin D is tricky to get from foods; sardines and fatty fish are the best sources, and small amounts occur in liver and egg yolks. Sunlight is the best natural source. Unfortunately, “modern kids are at school, watching TV, or playing computer games during daylight hours,” says Levin. “When they are running around outside, they’re usually slathered with sunscreen, which inhibits vitamin D production.” Vital for healthy immune function in childhood, vitamin D also reduces the risk of cardiovascular disease, cancer, osteoporosis, and autoimmune disorders throughout life—so consider whether supplementation may be warranted for your child. How much kids need: At least 1,000 IU per day. Find it in: Uncle Matt’s Organic Orange Juice, Horizon Organic Milk.