DEAR DR. BLONZ: I know you're not a medical doctor, but I was hoping for some general guidance about the care my mother, who was diagnosed with thyroid cancer, is receiving. We are in a managed-care plan through my father's job, and I was hoping you might have some idea of how we could go about getting a second opinion to confirm her diagnosis and treatment plan. My friends have been telling me many different things, but my parents seem content with whatever the doctor says. Advice? -- F.E., New York

DEAR F.E.: I deeply sympathize with your situation. Getting a second opinion regarding diagnosis and treatment can be an important part of the approach to any complex medical situation.

Cancer is not a singular entity with consistent features. As such, the diagnosis of cancer can depend on interpretation of medical evidence, and indicators of any cancer's unique characteristics are not always clear-cut. Doctors can differ in their approaches; some are conservative, while others are more aggressive. And medical facilities can differ in their familiarity with and use of evolving technologies.

You should work with your parents to voice your concerns and verify that your mother's diagnosis and treatment strategy make medical sense. If you feel it is appropriate, raise the issue of getting a second opinion. Most physicians will respect the request for a different set of eyes to review a case, and insurance may cover it. If possible, find a cancer center or a university-affiliated teaching hospital, ideally with faculty who have researched the type of thyroid cancer affecting your mother. The National Institutes of Health provides information on finding cancer centers and doctors at b.link/y55yveu. In addition, check the American Cancer Society's Cancer Survivors Network at b.link/yxhhe8q for discussions from other patients who have been down this road. My best to you and your family during this difficult period.

DEAR DR. BLONZ: I learned in school that riboflavin in milk is destroyed by light. If that is true, why is milk sold in clear containers? Am I wasting my money by paying more for milk in opaque containers? -- S.T., Tulsa, Oklahoma

DEAR S.T.: Milk is a perishable food, and exposure to natural or bright fluorescent light can destroy a percentage of riboflavin (vitamin B2), vitamin C and vitamin B6 and, over time, encourage the development of "off" flavors. Light intensity, duration of exposure and time away from refrigeration will determine how much these nutrients are affected.

A healthful diet should include nutrients from many sources, so minor losses from one food should not negate the nutritional value of that food. That said, storage in an opaque container, such as a paper carton, seems to be best in preserving milk's nutrients, while clear glass -- while aesthetically pleasing, and recyclable -- is not. Always check the product's date to be sure you are enjoying fresh milk. (Read more on food product dating at b.link/cbsr87.)

Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.

DEAR DR. BLONZ: I returned from a trip with a cold. Two close friends, who don't know each other, brought over their homemade chicken soup to help me recover. I recall my grandmother bringing it over when we were sick during childhood. Is there anything special about chicken soup for a cold, or is it the soothing of the warm liquid that does it? -- S.F., New York

DEAR S.F.: With winter comes cold and flu season, and many have the misfortune to succumb. I compliment your friends for offering homemade chicken soup. Not only does it help with its soothing warmth and taste, but it can also work with your body's immune system to help it gain the upper hand. History and science help make this case.

Chicken soup was noted as a remedy in ancient Rome, where Pedanius Dioscorides, Nero's army surgeon, wrote about its benefits in "De Materia Medica." In the second century, Greek physician Aretaeus of Cappadocia described chicken soup's use in treating respiratory disorders. Perhaps most notably, in the 12th century, Moses Maimonides, a prominent medical scholar, recommended chicken soup for colds, flu and asthma.

To understand the role chicken soup can play in fighting illness, it helps to review the sequence of events when a sufficient dose of the cold virus enters your upper respiratory system.

Recognizing a foreign microbe, our immune system reacts, assembling its team to isolate and defeat the virus. Inflammation is an element of the battle plan, which results in congestion and symptoms that include a runny nose, sore throat, minor coughing and headache. If the virus spreads to the lower respiratory tract, it can lead to more serious conditions like laryngitis, bronchitis or pneumonia. (Read more about the common cold at b.link/kuxxk6q.)

Congestion, while evidence of the immune system at work, can slow the healing process if it collects more rapidly than it can drain. Thinning and moving congestion out of your system can hasten recovery, so doctors recommend you stay hydrated, and will often suggest the use of an expectorant.

A classic study at Mount Sinai Medical Center in Miami found that chicken soup helps to clear congestion. Dr. Irwin Ziment, a pulmonary specialist at UCLA, attributed this to the amino acid cysteine found in chicken soup, which is similar to acetylcysteine, a medicine used to break up congestion. Chicken soup can also help some symptoms of asthma -- Maimonides recommended it because he found it helped clear mucus from the lungs.

Other research physicians, including Dr. Stephen Rennard of the University of Nebraska, reported that chicken soup might block inflammation and congestion caused by white blood cells in the windpipe. His experiment used a soup made with carrots, onions, sweet potatoes, turnips and parsnips, prepared by his wife, Barbara.

A basic chicken soup recipe involves cooking chicken in water with carrots, onions and celery. My personal recipe uses a roasted chicken to take advantage of its special flavor. Mimi Sheraton's James Beard Award-winning book "The Whole World Loves Chicken Soup" offers more than 100 chicken soup recipes from around the globe.

Chicken soup has a number of powers. Note that colds are caused by viruses, not bacteria, which explains why doctors resist prescribing antibiotics for colds. So, enjoy your chicken soup -- it would make your grandma proud.

Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.

DEAR DR. BLONZ: I am interested in nutrition and have heard about the benefits of folates, and how we need methylfolate, not other forms. Is folate the same as folic acid or methylfolate? Thanks! -- P.D.

DEAR P.D.: Nutrition is a branch of science focused on the intake of foods and their conversion to nutrients and energy in the human body. It's important to note that dietary supplements are a consumer product, so expect companies to argue the superiority of their product over their competitors'. Always consider the source, and seek evidence-based information rather than relying claims made by these businesses, whose main focus is making the sale.

Folate is a generic term referring to a family of related compounds. Throughout its history, this essential nutrient has been known by many different names, including Wills factor, vitamin M, vitamin Bc, vitamin B9, vitamin B10 and vitamin B11. Folic acid is a synthetic form not found in nature; it is used in supplements and to fortify foods. (More about this essential nutrient can be found at at b.link/d6arknb.)

In nature, folate's essential core can be found along with a side chain that reflects what it does in that particular plant or animal tissue. When consumed, our digestive system pares off extra folate to get it ready to pass through its absorptive portal in the upper part of the small intestine. Once through the intestinal wall, folate travels to our liver, where it is activated for use.

One can get the folate they need from a healthful diet. Good sources of folate include green leafy vegetables, organ meats, legumes, orange juice, beets, avocado and broccoli. Taking folate, folic acid or methylfolate supplements at their recommended levels is fine for most people.

One exception to consider is those with a genetic issue called methylenetetrahydrofolate reductase (MTHFR), which makes the body less effective at folate activation. For those affected, an adequate dietary intake is especially key. If their folate intake is marginal, they could benefit from methylfolate, the more active form. Ask your physician, as there are tests that can indicate whether your body needs special considerations regarding folate. (Read more about this gene variant and folic acid at b.link/mesk4bz.)

DEAR DR. BLONZ: You always recommend whole foods so that one gets nutrients where they naturally occur. But does that mean it's best to take vitamin C with foods that naturally include vitamin C, or is it just as effective to take it alone with water? What's the best time of day to take vitamins? -- C.F., Scottsdale, Arizona

DEAR C.F.: Vitamin C can be taken with or without C-containing foods. Generally, it is preferable to take supplementary vitamins and minerals at mealtime: When food is present, the body is more attentive to the digestive system and the blood supply can pick up the incoming nutrients. The main takeaway: It is more important that you get your nutrients than to be overly concerned about what time of day you get them. The foods you eat should always be center stage. Supplements are just that: supplements.

Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.