Dear Doctor: Are organic foods better for you than ordinary foods? I say yes because there are no hormones or pesticides involved. My husband says that once you wash your produce carefully, the only difference between an organic peach and a regular one is the price tag.

Dear Reader: Welcome to a long-running and robust debate. Whether organic foods provide health benefits over and above those grown by conventional methods has been under discussion for decades. (And here we're being polite -- both sides of this battle can get pretty worked up.)

Before we wade into the fray, let's take a stab at some definitions. That's actually easier said than done. At its most basic, when something is organically grown, it is understood to have been raised without the use of synthetic pesticides, herbicides or fertilizers; without antibiotics; and with seeds or products that have not been genetically engineered or altered.

Dig a little deeper (sorry) and the word "organic" takes a detour into the legal realm. In order to market their products as organic, farmers must adhere to specific guidelines put forth by the U.S. Department of Agriculture. So to simplify our discussion, let's go with the basic spirit of the word. That is, fruits and vegetables raised without conventional pesticides or synthetic fertilizers, and farm animals raised without the use of hormones, and with access to the outdoors and to pasture.

Are organically raised foods better for your health? Studies say maybe. Will we ever get a definitive answer? Probably not. The challenge is that the topic is so vast as to be virtually unmanageable. Even studies that have broken the question down into discrete parts come up with mixed results.

So what is known for sure?

When you buy organic produce, you're getting fruits and vegetables with measurably less pesticide residue than when you buy the same produce that has been conventionally grown. But before you take a victory lap, conventionally grown produce in the United States generally exceeds the minimum tolerance levels for pesticides set by the Food and Drug Administration.

As to why organic produce has any pesticide residue at all, some have been OK'd for organic farming. Drift from conventional farms, plus lingering DDT in the soil, are believed to account for the rest of the pesticide residue found on organic produce.

Studies show that organically grown produce also has higher levels of antioxidants and lower levels of the heavy metal cadmium than does conventional produce. And when it comes to beef, the FDA's feeding guidelines that call for organic cattle to be raised on grass and alfalfa lead to meat that is higher in omega-3 fatty acids. Increased levels of omega-3's are also found in organic dairy and eggs. On the minus side: Organically produced milk tends to be lower in iodine, an essential nutrient, than conventional milk.

In a paper published this year, researchers did the heavy lifting and systematically examined the published literature on the benefits of organic versus conventional food. Their findings: "It is therefore currently not possible to quantify to what extent organic food consumption may affect human health."

Bottom line: The "organic vs. conventional" battle rages on.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: Just how bad is it to give kids fruit juice before they turn 1?

Dear Reader: Fruit juice has been touted as "part of a nutritious breakfast" for years. As a child, I was told that juice was good for me, providing me with vitamin C. After all, it was a healthier alternative to sodas, and it tasted good. Today, kids routinely drink cranberry juice, orange juice, grape juice, apple juice and many other juices for those reasons. But now, with the epidemic of obesity and diabetes, adults are starting to think more carefully about the sugar content of fruit juice.

Fruit juice contains four sugars: sucrose, glucose, fructose and sorbitol. All of these, except sorbitol, are easily absorbed by the body and raise blood sugar and insulin levels. In addition, the sugars from juice that are not absorbed can cause bloating, abdominal pain and diarrhea in toddlers.

Another problem with fruit juice is that you easily get all the sugar of a fruit, but without the fiber. Take orange juice, for example. If you were to eat an orange, your hunger might be satiated enough not to eat another, thus limiting your sugar and caloric intake. However, an 8-ounce glass of orange juice might require four oranges. This is true for many other fruits as well. That's a lot of sugar and calories, with all their negative effects.

A recent policy statement from the American Academy of Pediatrics suggests that infants who drink fruit juice may be less likely to eat fruits when they are older, and, further, infants might be replacing milk with juice. Milk, in addition to sugar, has a substantial amount of the protein, fat and vitamins necessary for growth. However, juice has sugar and some vitamins, but no protein or fat. Not convinced? Excessive consumption of juice in children has been associated with malnutrition and short stature. (Note that because water lacks nutrients, it's not recommended for infants younger than 6 months.)

Another worry about the sugar in fruit juice is the effect it has on young teeth, because prolonged exposure to sugar leads to cavities. The risk is heightened when infants are given juice in a bottle or sippy cup, because they can carry the bottle or sippy cup with them -- drinking whenever they want. Both the American Academy of Pediatrics and the American Academy of Pediatric Dentistry recommend that juice be given only in an open cup to minimize how much a child drinks.

I agree that giving juice to children younger than 1 year of age is not healthy for them. But the same holds true for those older than 1. Juice may have some health benefits, but overconsumption will still ultimately lead to a greater risk for obesity, cavities and diabetes. So parents of older children should continue to control their consumption of juice. And, because they're not reliant on liquids for nutrition, teaching them to use water to slake their thirst is a good idea.

We've focused here on drinks that are 100 percent juice. The unhealthy elements of juice become even more pronounced when sugar is added to create a "fruit drink" or a "juice cocktail."

I understand that it's hard for a parent to say no to a crying infant who craves juice or a fruit drink. But doing so is much easier than trying to change entrenched unhealthy habits.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I just heard that instead of causing injuries, running may be good for your back. Is this true? If it is, I'm going to lace up my shoes and head back out to the trail!

Dear Reader: Running is one of those physical activities that, over the years, has accrued an almost mind-bending cache of contradictory advice. So it's no wonder that the results of a new study, which suggests that running can improve the health of the discs in your spine, have caught you by surprise.

Let's start with a look at the spinal column, which as we've said before is a marvel of engineering. With a minimum of moving parts, this gently s-shaped curve of bone, cartilage, collagen and protein gels supports the body and gives it structure. It allows multi-directional movement and protects the vital bundles of nerves that connect the brain to the rest of the body.

The vertebrae are the series of load-bearing bones that articulate the spine. These are connected to one another by gel-filled discs, which also act as shock absorbers. But the same interlocking structure that lends flexibility to the spine is also its most vulnerable feature.

How the repetitive stress of running affects the various parts of the spine, particularly the discs, has long been a subject of debate. In the study published last spring, scientists from Australia set out to answer the question and learn whether intervertebral discs can be strengthened. To that end, they studied the spines of 79 men and women between the ages of 25 and 35. One-third of them were not runners. In fact, that group rarely exercised at all. Of the runners in the study, all had been training for at least five years, and regularly logged anywhere from 12 to 30 miles per week.

With the use of advanced imaging techniques, the researchers measured the size and resilience of each participant's spinal discs. The results were surprising. The runners in the study, whose regular exercise regimen placed repeated demands on the shock-absorbing qualities of the spine, had intervertebral discs that were larger and filled with more fluid than did the group who rarely exercised. That is, their discs were healthier than those of the non-running participants.

Even more intriguing was the fact that the size of the vertebrae of the joggers, who totaled 12 to 25 miles per week, and the long-distance runners, who ran as much as 70 miles per week, were virtually the same. That is, total mileage didn't matter. Longer runs didn't make the spine healthier, nor did they cause deterioration.

Those of us who aren't runners will be happy the scientists didn't stop there. By parsing their data even further, they discovered that the health effect on intervertebral discs begins at a pace of 4 mph, or a brisk walk.

Although a single study can't definitively answer whether running is good or bad for the back, the results here add a layer of fascinating and encouraging information for runners and walkers alike.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)