Here in America, we've become a society so worried about skin cancer, that we've overlooked some of the good things that the sun provides for us. One of those things is an improvement in our mood. Another is Vitamin D. But Vitamin D is also obtainable through food including oily fish, eggs, fortified cereals, milk and orange juice. It can also be taken as a pill or liquid supplement.

Vitamin D works directly on the cells in the body, affecting metabolism the way a hormone dose. It is an extremely important vitamin, and we are finding out just how important with each new study. Deficiencies can lead to bone softening disease (rickets short term, or osteoporosis long term), dementia, heart disease, diabetes, Multiple Sclerosis, some cancers, autoimmune diseases, and infections.

As we lather ourselves and our children with sunscreen, we increase our deficiencies. A recent study from Children's Hospital in Boston revealed that 40% of infants were lacking in Vitamin D. Those especially affected had darker skin which interferes with absorption, or are from the Northeast, where there is less direct sunlight.

But the solution to the growing Vitamin D deficiency problem in our children is NOT to expose them to more sun. Supplying a liquid supplement by mouth is just too easy. The American Academy of Pediatrics has just wisely doubled the recommendation for infants and children to 400 IU daily. This amount is completely safe, and is the amount of Vitamin D found in a liter of infant formula.

The problem, believe it or not, is worse for mothers who are breast feeding. When was the last time you heard a doctor say that breast milk was deficient in anything? The problem may come from mothers not having enough Vitamin D, which is then lacking in their breast milk. It may be easily correctable by administering supplements to breast-feeding mothers rather than their infants, but this has yet to be studied. In the meantime, the Boston study showed 10 times the amount of Vitamin D deficiencies in infants of breast feeding mothers as compared to those who used formula feeds. This is a huge discrepancy, especially when you consider how easy it is to supplement this essential vitamin.

So use sunscreen on your children's skin, but at the same time consider giving them a daily drink of Vitamin D.

Dr. Marc Siegel is an internist and associate professor of medicine at the NYU School of Medicine. He is a FOX News Medical Contributor and writes a health column for LA Times, where he examines TV and movies for medical accuracy. Dr. Siegel is the author of "False Alarm: the Truth About the Epidemic of Fear" and "Bird Flu: Everything You Need to Know About the Next Pandemic". Read more at www.doctorsiegel.com

Dr. Marc Siegel, a practicing internist, joined FOX News Channel (FNC) as a contributor in 2008..