Wheel your race-car grocery cart down the vitamin aisle these days, and you're confronted with a dizzying array of supplements: A, B complex, calcium, iron, omega-3s. It's enough to make a parent's head spin.

This month, Dr. Lewis First, chief of pediatrics at Vermont Children's Hospital at Fletcher Allen Health Care, cuts through the alphabet soup of supplements with some simple advice.

KIDS VT: Let's talk about why vitamins and minerals are important.

LEWIS FIRST: Basically, they make our bodies work properly. Vitamins are made by plants and animals, and minerals come from the soil and water but also from the plants and animals we eat. Sometimes we don't make enough of these natural substances so we have to take them in through the foods we eat.

KVT: What are the most critical vitamins and minerals?

LF: The big ones are vitamins A, B, C and D, calcium and iron. Vitamin A keeps your skin healthy, helps your tissues repair and helps with color and night vision. Vitamin Bs help produce energy and make red blood cells. Vitamin C helps the body heal from an injury. Vitamin D and calcium are for tooth and bone formation as well as overall growth. Iron helps make red blood cells and muscles. The good news is you can find all these nutrients in the grocery store.

KVT: When would a child need a supplement?

LF: If your children aren't eating regular, well-balanced meals, if they're picky eaters, if they have an underlying medical condition that causes trouble digesting or absorbing nutrients, or if they're on a vegetarian diet, then your children will likely benefit from a vitamin supplement. These kids aren't necessarily going to need a multivitamin but possibly a specific supplement for whatever nutrient they're missing. Your child's health care provider can make that recommendation.

KVT: Can supplements be dangerous to children?

LF: Yes, if they're left out for a child to get. If you're going to keep vitamins in your home — particularly if they're chewables, taste like candy and look like cartoon characters — they should be safeguarded like medicine and locked away.

KVT: What if kids don't eat vegetables?

LF: If they're not eating their vegetables, they're probably still getting the vitamins they need from fruit. It's only if they're missing both fruits and vegetables that parents may want to consider a vitamin.

KVT: What about breast-fed babies?

LF: Early on, every baby who is breast feeding or those not getting a lot of dairy products must be on some source of Vitamin D because of possible deficiencies of that vitamin in the maternal diet. The American Academy of Pediatrics recommends that all breast-fed infants be given a Vitamin D supplement until the Vitamin D requirements of the lactating mother and infant are determined. Vitamin D can be metabolized in our bodies through sunlight, but in our particular environment, many kids don't get adequate amounts of sunlight during much of the year, and infants should stay out of the sun anyway due to their thin skin and the dangers of the sun's ultraviolet rays.

KVT: What about families on vegetarian diets?

LF: Depending upon what kind of vegetarian you and your children are, kids could be missing some of the basic vitamins in their diet, but they may still acquire them in other nonvegetarian foods if directed to these foods by a child's doctor. For example, if your children are not drinking cow's milk, they can still drink vitamin-fortified soy milk. My advice is, if you are using a diet that may be short in any of the four basic food groups, talk to your child's health care provider about adding a vitamin supplement.

KVT: What about the omega-3 fatty acids?

LF: You hear a lot about the omega-3 fish oils, which, theoretically, are beneficial for the cardiovascular system. But there's not a lot of data on the benefits of fish oils for children. Fish oil may help with brain development, but these data are controversial and not all studies show that omega-3 fatty acids make a difference in kids.

KVT: How about fiber supplements?

LF: If kids are not eating enough fruits and vegetables, this can lead to issues of constipation and belly pain, so a fiber supplement may be in order.

KVT: Any advice on probiotic supplements?

LF: Probiotics are types of bacteria that are friendly to our digestive system and can help us stay healthy. The most common ones we hear about are bifidobacteria and lactobacillus. These types of microbes make substances that keep cells in the intestines healthy and fight off unfriendly bacteria, yeasts and molds. We use antibiotics to kill bad bacteria, but we use probiotics to populate your digestive system with good bacteria. Probiotics are supposed to reduce your risk of diarrhea, lower the risk of food allergies and help you grow. However, most of the foods we eat, including yogurt, are already colonizing our gut with these good bacteria from the moment we're born.

KVT: If kids are eating a balanced diet, do they need to take a daily multivitamin?

LF: No. If parents are giving a multivitamin to a child who is staying on his or her growth curve, a multivitamin is not necessarily making a difference in the child's ability to grow and develop and thus is not indicated in an otherwise healthy child.