Dear Doctor: I recently began running again after a six-year hiatus. My only problem is that my heels hurt after I run -- so much so that I limp for a few minutes the next morning until my body adjusts. As the day progresses, I stop noticing the pain. Any suggestions?

Dear Reader: Running is supposed to be good for you, so it can seem perplexing and frustrating when, instead, it causes pain. In your case, I suspect the cause is plantar fasciitis.

The plantar fascia is a band of thick tissue that attaches to your heel bone (the calcaneus) and extends from there all the way to the base of your toes, providing support for the arch of your foot. Because the plantar fascia is prone to inflammation, it's a common cause of foot pain in adults. This inflammation, known as plantar fasciitis, is most common in adults ages 40 to 60 and accounts for nearly 1 million doctor visits each year in the United States.

One-third of the time, as in your case, the symptoms are on both sides. Runners and dancers are more likely to develop plantar fasciitis than people in the general population because of repetitive trauma. In runners, the pain can be related to poor-fitting running shoes; tightness within the calf, Achilles tendon and hamstrings; flat feet; or running on hard surfaces.

The typical symptom, which you described, is pain in the heel that is noted with the first step out of bed. The pain is sharp and may subside with walking, but may reoccur by the end of the day if an affected person is on his or her feet all day.

Your doctor can usually diagnose plantar fasciitis simply by examination, although he or she may recommend X-rays to rule out other causes for heel pain.

As for what you can do, I would recommend stretching. Tight calf muscles and Achilles tendons can cause the heel to lift so that the contact point with the ground when walking and running is at the area of the plantar fascia. Stretching the calf and even the hamstring can help change that contact point. A foam roller can massage and stretch the calf and hamstring, as can a nighttime splint that keeps the calf stretched and the foot flexed upward. Also, just as stretching the back of the leg is helpful, so is strengthening the muscles at the front of the leg. A physical therapist can recommend specific exercises.

Other pain-reducing tips include buying shoes with good arch and heel support, and using heel inserts to cushion the heel while walking or running. NSAIDs such as ibuprofen and naproxen can decrease inflammation and pain, as can icing your heels after a run.

Finally, you should curtail the running until the pain in your heels subsides. Don't resume it until you've improved your biomechanics through stretching and strengthening exercises.

If the pain persists, a doctor may recommend a steroid injection into the heel, but this should be reserved for people who have not been helped by physical therapy and courses of oral anti-inflammatories.

(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 have Type 1 diabetes and have used marijuana for years to control my blood sugar. I've seen my blood sugar drop 100 points in five minutes with marijuana, a lot faster than my Humalog insulin can manage. Why is that? Will medical marijuana ever go mainstream?

Dear Reader: Marijuana, or cannabis, contains more than 100 active chemical compounds. Known as cannabinoids, each of them behaves differently in the body. As the number of states that allow the use of cannabis for medical purposes continues to grow, so does the body of evidence that many of the compounds found within the plant have therapeutic potential. The most common use of cannabis in the United States right now is for pain control. It's also widely used for anxiety, to manage nausea and has been shown to be effective in reducing inflammation. It also shows promise in managing symptoms of neurological conditions like Parkinson's disease and multiple sclerosis.

The challenge to investigating medical claims regarding cannabis is the fact that, despite what's happening in individual states, it remains illegal at the federal level. Cannabis is a Schedule l drug, in the same category as heroin, which means research is subject to numerous restrictions. Even so, various studies and clinical trials are moving forward, and in time we will learn more about what cannabis can -- and can't -- do.

In researching your question regarding cannabis and diabetes, we found that you're not alone in noticing its effect on blood sugar. However, much of what we found is anecdotal evidence, which lacks scientific rigor. At this time, the study of cannabis and its potential effects on diabetes is in the early stages, with much of the work done in mice and on donated tissue samples. Until researchers are able to work extensively with human populations, the how and why of the effects of cannabis on the complex physiologic processes encompassed by diabetes will remain educated guesses.

Preliminary research suggests that certain cannabinoids may help with glucose control. Some studies have found that cannabis can have a positive effect on insulin resistance. A study published in 2016 in a journal of the American Diabetes Association found that THCV, one of the cannabinoids that are not psychoactive, improved glycemic control in some individuals with Type 2 diabetes. Another study that same year drew a link between cannabidiol, a compound in cannabis, and a decrease in inflammation of the pancreas. In an observational study using data from the federal Centers for Disease Control and Prevention, researchers found the incidence of diabetes among regular cannabis users to be measurably lower than that of the population at large. At the same time, the results of several other recent studies contradict a number of these pro-cannabis findings. So, basically, the jury is still out.

Although cannabis shows promise in the area of diabetes, science has yet to catch up with the claims being made. In the research that has been done, the reason for the effects of cannabis are not yet fully understood. Interest in the subject is strong, though, and continues to grow. We'll keep an eye on the topic for you and report back as we learn of new advances.

(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: My daughter isn't a flight attendant, but she flies a lot for business. Is she at an increased risk for cancer?

Dear Reader: Commercial airline flying is a relatively new experience. The concept of flying to multiple locations for business would have been inconceivable 100 years ago. The evolution of the human body has not been adapted to flight, so the exposure of humans to prolonged airplane travel is a change that may have health consequences. At higher altitude there is greater exposure to ionizing radiation. Flight attendants and pilots spend much of their working time 30,000 feet above the Earth's surface, so their health may give us an indication of potential hazards with flying.

A recent study in the journal Environmental Health looked at 5,366 former and current flight attendants and compared them with a control group of the same age and health. More than 80 percent of the flight attendants were women. The average age of the participants was 52 and the average duration at the job was 20 years.

The authors looked at the number of cancers in the flight attendants and found a greater rate of cancer overall compared with the control group. In women, there was a 51 percent greater prevalence in breast cancer, a 2.27 times greater risk of melanoma and a 4.09 times greater risk of other types of skin cancer. The elevations of skin cancer were not as great among male flight attendants. There were also increases in the rates of uterine, cervical, gastrointestinal and thyroid cancer among female flight attendants.

The rate of cancer increased with every five-year increment in the air for non-melanoma skin cancers, but this was not noted with other types of cancer. This result is confusing because one would believe there would be greater numbers of cancers based on greater flight time. What is also confounding is that the flight attendant group had fewer children on average than the control group, which should lower the rate of breast cancer in the control group compared to the flight attendants (the greater number of children a woman has incrementally lowers the rate of breast cancer). The authors, though, still found a modest increased rate of breast cancer in flight attendants with the same number of children as the control group. Lastly, the study doesn't take into account the amount of time flight attendants spent on layovers and vacations in the sunshine. This would appear to be greater than the control group and could be a reason for the increased rate of skin cancer.

Nonetheless, ionizing radiation is a risk factor for breast and non-melanoma skin cancers. Cabin crews have the highest annual ionizing radiation dose out of all American workers. While I believe there is a greater risk of cancer among flight attendants, I also feel that confounding factors may make the risk less than what is reported.

But this doesn't really answer the question regarding your daughter. Flight attendants have a substantially greater number of hours in the air than your typical business commuter. Thus, I feel your daughter may not be at a significant risk of cancer from her relatively short time in the air. But I would feel even more comfortable saying this if there were some way to protect both passengers and cabin crews from ionizing radiation.

(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.)