I'm never quite sure what to do about vitamin supplements. Should I take them? Or should I leave them?

Sometimes I think supplements could surely help me with whatever I'm lacking in my diet. Other times I don't want to mess with what might be working just fine in my body. Now if a doctor tells me my iron is low, I'll take a supplement to boost my levels. But if there is nothing apparently off kilter in my system, I tend to just leave things alone.

I'm glad at the moment for my current plan. Because nutritionists now suspect that high doses of vitamins and minerals -- believed by some to prevent cancer -- might actually be harmful.

Think about this:

The American Medical Association journal JAMA recently reported that high doses of antioxidant supplements can be harmful. Vitamin advocates challenged the analysis, saying it excluded large studies from China and Italy showing antioxidant supplements lowered mortality risk.

Consumers still should read labels carefully.

"Some of the things called daily vitamins can be higher than what we think is desirable," says one researcher who urges consumers to look for something about 100 percent of the daily value. That's really all people need, she declares. But a healthy diet is still most important and can prevent the need for supplements altogether. Yet for those who are sick, don't have access to nutritious food or for some other reason cannot eat well, the 100-percent rule is a good guide.

Children and teenagers -- mostly girls -- need zinc, a mineral important for maintaining healthy immune systems and healthy skin and for preventing colds and infections. Yet half of all teenage girls have zinc deficiencies.

Red meat is the most effective way of channeling zinc into the body. Perhaps these young girls are eating red meat less than two times per week -- a practice research shows can contribute to zinc deficiencies.

Iron is vital for good health. Menstruating women need it. The elderly need it. Pregnant women need it. And children need it too. But many lack healthy levels of iron.

Red meat contains a lot of iron. And while iron also comes from vegetable sources, meat contains more iron than most foods and is best utilized by the body in this form.

Red meat also contains B vitamins, phosphorus, potassium, magnesium, selenium -- and protein, critical for muscle and organ health. Protein from red meat is complete, meaning it contains all the amino acids the body cannot make on its own. Protein helps the body repair and renew.

There is definitely a good side to eating red meat. There is also a bad side.

Red meat has been linked to incidences of bowel cancer, breast cancer, heart disease, Alzheimer's disease, osteoporosis, arthritis, high cholesterol, clogged arteries, and food poisoning.

Experts say the controversy surrounding red meat comes down to the type of meat we are eating -- and how we are eating it.

There are three official red meats -- pork, lamb, and beef. Pork is the leanest, lamb is the fattiest, and beef is the most nutritious. Red meat is typically high in saturated fats and bad cholesterol. But lean beef is fairly healthy -- if it's not treated with hormones and is truly free from excess fat. The more white you see, the more fat you get.

So here is the trick for all meat-eaters out there -- choose lean meats, seek nutritious cuts of meat, avoid hormone-treated products, steer clear of processed meats (these include more additives and fats than simple cuts of pork, lamb, and beef), read labels carefully, make meat just one component of a balanced diet, and brace yourself for more research and study and discussion that will undoubtedly conclude that meat is good for us. And bad for us too.