Callers voice their concerns about a variety of topics, including the health implications of drinking diet soda and the safety of petroleum jelly. Dr. Oz and Lisa Oz answer these questions and more.

Is petroleum jelly safe to use as a moisturizer?
Dr. Oz says he doesn't recommend you use petroleum jelly anywhere on your body because it is not a natural product—it is a by-product of oil production. Lisa agrees and says natural moisturizers, such as coconut, lanolin, jojoba nut or grape seed oil, should be used instead. "The natural approaches are usually the safer ones just because you can guarantee that you will absorb some of this material through your skin," Dr. Oz says.

Is caffeine-free diet soda healthier than regular soda?
Dr. Oz says not only do the chemicals in diet soda stay in your body for 36 hours, the sweetness of noncalorie soda tricks your mind and might contribute to high cholesterol, high blood pressure and high blood sugar. "When you drink a diet soda, your brain is getting feedback that you are having something sweet, but it is not getting any extra calories," he says. "People who have diet drinks also tend to eat more simple carbohydrates; they crave them because they didn't get them when the sweetness hit their tongue." If you are going to drink soda, Dr. Oz says to drink a regular one and do so rarely.