Two cups of milk a day are enough for most kids, researchers say based on a new study. That gives children enough vitamin D from the milk, the study found. But it avoids reducing their supply of iron, as larger amounts of milk can do. The study included more than 1,300 healthy children. Parents reported how much milk the children drank. Researchers measured their levels of vitamin D and iron. Children who drank more than 2 cups of milk daily had lower levels of iron than those who drank 2 cups. But those who drank 2 cups a day had enough vitamin D and iron. The exception was children with darker skins. In the winter, they needed to drink 3 to 4 cups of milk to get enough vitamin D. The journal Pediatrics published the study online. HealthDay News wrote about it December 17.

By Henry H. Bernstein, D.O.
Harvard Medical School

What Is the Doctor's Reaction?

Got Milk? Children are often told to drink their milk because it will help them "grow big and strong." In the United States and Canada, more than 70% of children drink cow's milk every day!

Cow's milk is a major source for vitamin D in young children. This helps keep bones healthy. Iron is needed for good health, too. But cow's milk only has a small amount of iron in it. Cow's milk also makes it harder for the body to absorb iron that is eaten at the same time. Plus, drinking too much milk causes young children to lose blood (and iron) in their gut.

So what is the right amount of milk young children should be drinking each day? Children need enough milk to get vitamin D, but not too much, since it lowers the amount of iron in the body.

In a new study published in the journal Pediatrics, researchers tried to answer this question. They studied more than 1,300 healthy children between 2 and 5 years old. The average age was 4. They looked at how much milk these children were drinking each day. They also checked what their levels of vitamin D and iron were in the blood.

Among these children, drinking more milk was linked with higher levels of vitamin D. But drinking more milk also was linked with lower levels of iron. For each cup of cow's milk the child drank:

• Vitamin D levels went up 7%
• Iron levels went down by 4%

The researchers concluded that, for most children, two cups of milk was the best amount to drink each day. It gave young children the right amount of vitamin D, while not lowering their iron levels too much.

There was one exception. Children with darker pigmented skin should have 3 or 4 cups of milk daily during the winter. This is because days are shorter, so children are exposed to less sunlight in the winter. With less sunlight around, this group of children will not make enough vitamin D.

It was also found that children ages 2 to 5 who were given milk in a bottle did not take in more vitamin D. The researchers did note that their iron levels went down even more. This is one of the reasons that children should stop using a bottle at 12 months of age.

What Changes Can I Make Now?

Vitamin D and iron are very important nutrients for children. Your child's diet also should include other key vitamins and minerals.

To help your children grow big and strong, be sure they get these vitamins and minerals in their meals.

• Vitamin A is important for growth, healthy skin and tissue repair. It also helps with night and color vision.
  
  • Found in yellow vegetables, dairy products and liver
• B vitamins help red blood cells to form and assist with many bodily activities.
  
  • Found in meat (including liver), poultry, fish, soybeans, milk, eggs, whole grains and enriched breads and cereals
• Vitamin C strengthens connective tissue, muscles and skin. Helps to quicken the healing of wounds and bones. It also protects children from infection.
  
  • Found in citrus fruits, strawberries, tomatoes, potatoes, Brussels sprouts, spinach and broccoli
• Vitamin D helps teeth and bones form. It also helps the body absorb minerals such as calcium.
  
  • Found in fortified dairy products, fish oils, fortified margarine and egg yolks
  • Sunlight also helps the body make vitamin D
• Iron is important for making blood and building muscles.
  
  • Found in beef, turkey, pork and liver
  • Spinach, beans and prunes also contain iron
  • Some cereals and flour are enriched with iron
• Calcium is necessary for healthy bone development.
  
  • Found in milk, cheese, yogurt and sardines
  • Some vegetables, such as broccoli and spinach, also have calcium in them.
  • Some fruit juices are now fortified with calcium. This can be another good source of calcium.

What Can I Expect Looking to the Future?

You can expect your pediatrician to talk with you about how important it is for your child to have a diet rich in vitamins and minerals. A pediatrician can help you plan a healthy, balanced diet for your child. You can also talk with a nutritionist, if you need more guidance.

Researchers will continue to study the best ways for children to get all the vitamins and minerals they need to stay healthy.

Milk is a great source of calcium and vitamin D. But it also lowers iron stores in children. So parents need to remember that 2 glasses of milk, 8 ounces each, per day is the right amount for most children all year round. New ways of teaching parents these important messages about cow's milk will be created.