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.)

Dear Doctor: While my wife and I were working in the garden, she got dizzy and couldn't understand what I was saying. It went away after a few minutes, but I took her to the ER anyway. The doctors said she had a TIA. What is that, and is it dangerous?

Dear Reader: Your wife experienced a transient ischemic attack, or TIA. Also known as a mini-stroke, a TIA happens when part of the brain is temporarily deprived of blood flow.

You were right to seek immediate medical help. The symptoms of a TIA and those of a major stroke, which is the fifth-leading cause of death in the United States, are quite similar. And though the effects of a TIA are temporary -- that's the "transient" in the name -- that doesn't mean they're harmless.

First, let's talk about what's going on.

Ischemic strokes occur when a blood vessel in the brain becomes blocked, often by a blood clot. As a result, the part of the brain that is fed by that vessel is starved of blood. Since blood carries oxygen, which is vital to survival, it takes just a few minutes for brain cells to begin to die.

Unlike in a major ischemic stroke, where the blockage persists and damage can be permanent, a TIA resolves quickly. Sometimes it takes just a few minutes, and sometimes the effects can last up to 24 hours. When the TIA is over, the person feels normal again.

Symptoms of a TIA include the dizziness and cognitive lapse that your wife experienced. Additional symptoms may be a sudden headache, impaired vision, numbness or weakness in the face or limbs, garbled speech, and loss of balance and coordination.

The federal Centers for Disease Control and Prevention classify a TIA as a medical emergency. Although impairment due to a TIA is temporary, the event itself is a warning sign that needs to be addressed. A person who has experienced a TIA is at increased risk of a full-blown stroke, particularly in the first few days after the attack. However, with prompt treatment, as well as certain lifestyle changes, you can decrease the chance of a future stroke.

Your wife should see her primary care physician to discuss what happened and to begin treatment. This typically includes taking aspirin, a blood thinner that makes your platelets less likely to clump together. Aspirin should be initiated and continued under a doctor's supervision.

The good news is that your wife can also make some simple lifestyle changes to decrease her risk of another episode:

-- Keep blood pressure under control.

-- Don't smoke, and avoid secondhand smoke.

-- Maintain a healthy weight.

-- Eat plenty of fresh fruits and vegetables.

-- Exercise regularly.

-- Avoid stress.

-- Get enough sleep.

-- Limit alcohol.

Even better news: Every one of these suggestions will make you healthier, too.

(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.)