Dear Doctor: Colorectal cancer is rising among young people, as I recently read in a news report. But why? I thought colorectal cancer required a lifespan of unhealthy behavior.

Dear Reader: When I went through medical school, my professors had the same notions about colon cancer. The prevailing belief was that colon cancer was predominantly a disease of those over 50. Yes, colorectal cancers did occasionally occur in younger people, but these cases were attributed to familial diseases such as Lynch syndrome or familial adenomatous polyposis, or to a significant family history of colon cancer. Ulcerative colitis or extensive Crohn's disease could also put younger people at risk of colon cancer.

However, data have been warning for several years now of a rise in colon cancers diagnosed prior to the age 50. A 2015 study in JAMA Surgery looked at colorectal cancer data from nine states between 1975 and 2010. During that time, the overall rate of colon cancer decreased -- but only because the rate of colon cancer after the age of 50 decreased. In that study, 92 percent of colorectal cancer cases occurred after age 50; 8 percent occurred before age 50; and only 1 percent occurred between the ages of 20 and 34. In that same study, the 35-to-49 age group experienced little change in the colon cancer rate, but among those ages 20 to 34, the rate of colorectal cancer cases increased by 2 percent per year.

When the researchers looked specifically at localized (meaning they hadn't spread) rectal cancers and sigmoid colon cancers in this younger age group, they found that the rate of these cancers had increased by 4 percent. Because the total numbers of colorectal cancers in this age group was small, the increased rate of cancer in that age group was also small. But the authors noted that over the next 20 years, the rates may continue to increase at the current rate, and a substantial number of cancers, especially in the rectal and sigmoid areas, may be diagnosed among people ages 20 to 34.

A 2017 study looked at similar data from the same nine states between the years 1974 and 2013 -- and had similar findings. As expected, the rates of colorectal cancers decreased in those over 55 and decreased even further in those over 70. Among people ages 20 to 40, the cancer rates decreased between 1974 and 1985, but then substantially increased between 1985 and 2013. Between 1985 and 2013, people ages 30 to 39 had a rate increase of about 1 percent, and those 20 to 29 had a rate increase of 2.4 percent. Again, the absolute rate of colorectal cancers in this age range is low, such that the incidence increased from 1 in 200,000 people per year to 1 in 100,000 per year.

But why the increase? Consider that the increased rates of colorectal cancers in this younger age group coincide with increased rates of obesity among young Americans, with multiple studies confirming the correlation. Further, colorectal cancer has been linked to decreased consumption of fruits, vegetables and fiber and an increased consumption of processed meats -- characteristics of a modern American diet reliant upon processed food.

Although the rates of colorectal cancer in younger Americans are still relatively low, the increased incidence in this age range is emblematic of unhealthy habits among younger Americans. If those habits don't change, we can expect the colorectal cancer rates to keep rising.

(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: A neurologist diagnosed me with vestibular neuritis after an "event" a year ago that put me in the hospital for a week. My MRI was unrevealing, but I am still unbalanced and find it hard to get around. Besides physical therapy, can anything else be done?

Dear Reader: Vestibular neuritis is a condition that occurs when either the inner ear, or the nerves that connect the inner ear and the brain, become inflamed due to infection. This results in dizziness (vertigo) that can range from mild to severe. In the most severe cases, vertigo can cause a constant spinning sensation that makes it difficult to stand or walk, and can cause headache, nausea and vomiting.

What exactly is vestibular neuritis?

The word "vestibular" refers to the vestibular system. This is the portion of the inner ear and the brain that interprets the sensory information the body uses to regulate balance and control eye movements. Neuritis is a general term for diseases in which a nerve or a group of nerves becomes inflamed.

When the vestibular system is healthy, the signals to the brain from the left and right sides of the body match up. When the nerves on one side become swollen due to inflammation, the information sent to the brain gets scrambled. This results in the brain being unable to match up what the left and right sides of the body are saying, and the result is varying degrees of vertigo.

Balance is affected, and vision or hearing may also be involved. Some people find it difficult to concentrate, and some experience tinnitus, which is the presence of a ringing sound with no outside source.

Most inner ear infections are viral in nature. Unfortunately, not a lot is known about how these infections are transmitted. In many cases, the viral infection runs its course over a period of weeks and symptoms go away. In some cases, if the vestibular nerves have been damaged, the dizziness can persist.

As you probably learned, there is no definitive test for vestibular neuritis. The MRI that you had was not to diagnose vestibular neuritis, but rather to rule out conditions with similar symptoms such as head injury or stroke. Other conditions with similar symptoms include allergic reactions, the side effects of certain prescription or nonprescription medications, a neurological disorder or anxiety.

In cases where dizziness persists, further testing may be appropriate. This is done to confirm that the diagnosis is correct, and to pinpoint the location of the problem within the vestibular system. In addition to a hearing test, a physician or audiologist may recommend electronystagmography or videonystagmography tests used to evaluate the vestibular system. A short course of steroids may be recommended to decrease the inflammation in the vestibular system. The hopeful news is that, over time and with the help of rehabilitation exercises, the brain adjusts to the altered signals and the dizziness can abate.

(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've had gout three times in the last three years. I was prescribed Colcrys and indomethacin, but I'm finding confusing information about foods and beverages. One site told me to avoid potatoes and chicken. Other sites said I could drink wine. Any advice would be appreciated.

Dear Reader: The correlation between gout and elevated uric acid in the bloodstream was discovered in the mid-19th century. The problem is that in joints, where the temperature is cooler than in the bloodstream, elevations of uric acid cause the formation of monosodium urate crystals. This is most common in the big toe joint and in the ankle. White blood cells then engulf the uric acid crystals, creating even more inflammation. The result, as you know, is an extremely painful joint.

The first aspect you should assess is your weight. A 2005 study that followed 47,150 men for 12 years found that those with a BMI greater than 35 were three times as likely to develop gout than those with a BMI between 21 and 23. In addition, those who gained 30 pounds during the study were twice as likely to develop gout, while those who lost 10 pounds had a lower risk.

In line with this, the consumption of sugary sodas has also been associated with gout. A subsequent analysis of the data found men who drank five to six sugar-sweetened sodas per week had a 29 percent increased risk of gout compared to men who drank less than one serving per month. Those who drank one soda per day had a 45 percent increased risk, and those who drank two or more servings per day had an 85 percent increased risk. Researchers did not see an association between gout and consumption of diet soft drinks.

The next aspect you should assess is your alcohol consumption. Beer, wine and liquor have all been associated with gout attacks. In a study of people with a history of gout, two to four drinks within 24 hours increased the odds of having an attack by 51 percent. Even one drink increased odds by 13 percent. In regard to wine: If you have never had gout in the past, wine appears safe. But in this study, of those who had gout, even one glass or less of wine was associated with a 26 percent increased risk of a gout attack.

A low-purine diet is often touted as a way to decrease gout attacks. Foods that are high in purines -- a type of chemical compound -- include sardines, anchovies, herring, mackerel, scallops, liver and other organ meats. Beer is also high in purines. If you have gout, you'd be wise to eliminate or severely restrict such products in your diet. Other foods, including a variety of meats and fish, have moderate purine levels, but they won't make a large difference in your uric acid level, so there's no need to be overly restrictive toward them.

That said, other types of protein -- found in dairy, soy and other beans -- have been shown to lower uric acid levels when compared to the protein found in meat and fish. Cherries have also been shown to reduce the risk of gout attacks, although the mechanism is unknown. Vitamin C, too -- at a daily 500 milligram dose -- has been shown to slightly lower uric acid levels.

Lastly, check your medications. Hydrochlorothiazide (a diuretic), aspirin and niacin can all increase the uric acid level within your bloodstream and increase your chance of a gout flare.

My essential advice is: If you're overweight, try to lose weight. The most simple way to start is to avoid desserts and sugary drinks. Second, if you drink alcohol, either eliminate it or limit yourself to not more than one drink per day. Third, stay away from foods that are very high in purines.

Each of these steps will lower your risk of a new painful gout attack -- and put you on the road to an overall healthier lifestyle.

(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.)