Dear Doctor: My son is obsessed with electronic gaming. He spends hours a day doing this. Is this unhealthy?

Dear Reader: I have a teenage son as well, so this is a question with which both you and I struggle. When I was younger, in the infancy of computer games, the games were of low resolution and the goal was simply to develop enough skill to master them. To me, this was a fun activity, often separating me from the mundane and stressful activities of everyday life.

Today's games are more complex, requiring a variety of skills in complex reasoning and hand-eye coordination. Proficient players record their techniques on YouTube, and the truly elite compete in auditoriums, watched online by hundreds of thousands of people. Is there a downside to this? Definitely -- if parents don't manage it properly.

The first potential problem with these games is the prolonged sitting required. This type of sedentary behavior can lead to obesity.

A 2004 study performed in Switzerland compared obesity rates and the hours that people spent either playing electronic games or watching television. Researchers found a significant correlation between playing electronic games and obesity, with a connection especially likely among people who spent more than two hours a day playing games. On the plus side, the obesity rates were not as high among game-players as among people who watched television, supposedly because of the passive nature of watching television and the greater amounts of unhealthy food consumed while watching it.

Other studies have not shown this obesity risk, but then they've only compared the risk of more than one hour of gaming per day versus less than one hour of gaming per day.

In a study by the American Academy of Pediatrics in 2009, children and teens who said they played more than 45 minutes of video games per day were more likely to report poorer health and increased psychological distress than those who played less than that amount. Those gamers also were found to have more behavior problems.

And consider this: In an Australian survey study of 3,000 adolescents ages 11 through 17, those who had the highest levels of psychological distress were those who spent the most time playing electronic games or roaming the internet. It may be that gaming itself is not the full problem. Rather, the gaming may be an outlet for children with emotional issues.

However, the biggest problem with gaming is that it can be addictive. The Diagnostic and Statistical Manual of Mental Disorders (DSM 5) identifies Internet Gaming Disorder as a condition that warrants further studies.

My feeling is that electronic games can have benefits for children and adolescents, but exposure to them must be limited.

I recommend that you watch for addictive behavior from your son in connection to these games and that you limit the amount of time he spends with them each day. The American Academy of Pediatrics recommends no more than two hours of screen time per day. If your son is playing these games and in addition watches television, he may have an increased risk of obesity, poorer health and behavior problems.

When it comes to activity, keep two other pieces of advice in mind. One, encourage your son to substitute more active video games over the more passive variety and, even better, encourage him to pursue sports and other forms of exercise.

(Robert Ashley, M.D., is an internist and assistant professor of medicine at the University of California, Los Angeles.)

(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.)

Dear Doctor: My sister has decided to switch her entire family to a vegan diet, including her 2-year-old twins. But I'm really worried -- is it possible for young children to stay healthy and get all of the nutrients that a growing body requires?

Dear Reader: Unlike a vegetarian diet, which cuts out meat, poultry and fish, the vegan approach eliminates all animal-based products. It centers instead on whole grains, legumes, nuts, seeds, fruits, vegetables and leafy greens.

Some people choose a vegan diet for health reasons, others for ethical ones. But because not all nutrients essential to human health are present in plants, vegans face special challenges to ensure that their diet is well-rounded.

A vegan diet for young children has gotten a lot of bad press recently. A mother in Pennsylvania, who fed her infant only nuts and berries in an effort to go vegan, was recently charged with child endangerment. In Italy, where a number of vegan babies wound up in the hospital with malnutrition, some lawmakers want to make a plant-based diet illegal for anyone under 16.

But these are extreme cases. Proponents of plant-based diets say the real culprit is ignorance of proper nutritional principles, not veganism itself. With care and vigilance, and with the guidance of a pediatrician or registered dietitian, a well-balanced vegan diet can provide the nutritional needs of children and adolescents.

One of the most important parts of childcare is proper nutrition and feeding. Due to their more intensive nutritional requirements, children and adolescents are more susceptible to malnutrition when following an atypical diet. With a relatively short window in childhood during which critical growth in the brain, body, skeleton and internal organs takes place, it's all too easy for a child's diet to adversely affect future growth and development.

Vitamin B-12, vitamin D, iron, zinc, calcium and essential fatty acids are key nutrients for proper development in babies and children. Getting an adequate amount of B-12, which is provided by milk and eggs in a traditional diet, and meeting the minimum requirement for iron, which is present in red meat, is of particular concern in the vegan diet.

As there are no known plant sources for vitamin B-12, and without meat to provide essential fatty acids and other nutrients, providing a nutritional supplement, such as a multivitamin, is essential to normal growth and good health.

Another concern is that the plant-based diet is less nutrient-dense and more difficult to digest than the traditional diet. It not only takes more food to meet caloric and nutritional needs in a plant-based diet, it requires a greater amount of energy for the body to extract nutrients. Including concentrated sources of energy such as nuts and nut butters, soy products and legumes will help support appropriate growth.

If your sister does her homework, works in partnership with her primary care physician or a dietitian, makes sure the children get the full range of nutrients they need and are hitting their growth milestones, having a healthy vegan family is indeed possible.

A final thought -- going vegan is a radical change. Perhaps suggest to your sister that the family do a dry run, for instance Vegan Wednesdays for a month or two? If that works, then they can expand slowly until veganism becomes a family lifestyle.

(Eve Glazier, M.D., MBA, is an internist and assistant professor of medicine at UCLA Health. Elizabeth Ko, M.D., is an internist and primary care physician at UCLA Health.)

(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.)

Dear Doctor: My teenage daughter got the HPV shot. Should my son get it as well?

Dear Reader: The vaccine against HPV infection was initially created for females under the age of 26 to reduce the risk of cervical cancer. Human papilloma virus, or HPV, has been shown to be the cause of virtually all cervical cancer cases in women. Thus, if you decrease the possibility of infection with HPV, you would decrease the rates of cervical cancer, a disease diagnosed in 12,000 to 13,000 women in the United States each year. That's all for the good among females, but your question -- a logical one -- was about the benefit to males.

In men, HPV infection can lead to penile cancers, anal cancers and oral cancers. It has been estimated that 70 percent of cancers of the oropharynx are related to HPV. If that is the case, HPV-related cancers are diagnosed in about 11,000 men in the U.S. per year, so the vaccine would appear to have benefit for males as well.

The other benefit of the vaccine -- for both men and women -- is the prevention of genital warts. These warts are not life-threatening, but they're more than a nuisance to the people who get them. The Gardasil vaccine, the most common HPV vaccine, protects against four types of HPV. In addition to protecting against HPV types 16 and 18, which cause many HPV-related cancers, the vaccine also protects against types 6 and 11, which cause 90 percent of genital warts.

The benefits of giving boys the HPV vaccine appears to be enough to recommend giving the vaccine to your son. In addition, by giving your son the HPV vaccine, you will also decrease the likelihood that the virus will be passed on to other people. Providing the vaccine to boys nationwide will lead to less HPV in the community, which will in turn lead to a decrease in cervical, penile, anal and oral cancers.

The biggest problem with the HPV vaccines is the rate of vaccinations. Only 6 of 10 adolescent girls have started the HPV vaccine series, and only 5 of 10 adolescent boys have started it. As there is a two- to three-shot regimen for these vaccines, I can understand if your son does not want to get the vaccine simply to prevent a hypothetical cancer or wart.

However, as a society, we vaccinate against many other illnesses at a much higher rate even when the incidence of those illnesses is quite low. HPV is a very common infection and leads to multiple cancers and genital warts. I'm glad your daughter received the vaccine. Your son should get it too.

(Robert Ashley, M.D., is an internist and assistant professor of medicine at the University of California, Los Angeles.)

(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.)