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.

DEAR DR. BLONZ: I am 5 feet 4 inches tall and weigh 110 pounds on a good day. My concern is that I have found that 1,000 calories is the most I can consume each day without becoming obese. This seems a bit under what I should be able to eat, but the scale has its persuasions, and I dislike letting myself go. I wonder how to determine an ideal body weight and daily calorie count. -- F.S., Scottsdale, Arizona

DEAR F.S.: The "ideal body weight" (IBW) was developed to help estimate how long it takes for drugs to be metabolized, which helps to determine appropriate doses of medications.

According to reference tables, an IBW for an adult of your height is between 97 and 127 pounds for females, and 114 and 143 pounds for males. Overweight is considered to start at 10% above a person's IBW, and obesity begins at least 20% above. At present, you show little risk of being overweight or obese. (For more information on ideal body weight in relation to height and age, see b.link/m6jdjc8.)

The 1,000-calorie daily limit you mention is on the low side for your height and weight. Consider discussing this concern with your health professional to rule out any metabolic issues, medications or other factors that may be at play.

What is a reasonable number of calories to consume every day? Estimates for an inactive adult are 10 calories per pound of body weight. A sedentary adult who is minimally active most of the day would need 13 to 14 calories per pound. An adult with a moderate activity level would need about 15 calories per pound of body weight, and very active adults need about 18 calories per pound.

These numbers are averages. The greater one's muscle mass, the more energy one needs -- even when just sitting around.

DEAR DR. BLONZ: I get nutrients, including protein and dietary fiber, from my daily use of 100% whole wheat bread. I like my bread toasted for breakfast and for sandwiches, and I wonder if there is a loss of nutrients when toasting bread. -- N.C., Raleigh, North Carolina

DEAR N.C.: The heat-sensitive vitamins include vitamins B1 (thiamine), B5 (pantothenic acid), B6 (pyridoxine), B9 (folic acid) and C (ascorbic acid), as well as some amino acids, which are the building blocks of protein. (Minerals are not affected by heat.) Lysine, an essential amino acid in grains, is an example of a nutrient that would be affected by toasting. Heat-sensitive nutrients are in grains but are more abundant in other foods. You might benefit from avoiding the toaster if toasted bread were your primary food, which it shouldn't be. There are plenty of other healthful foods to enjoy.

Take the amino acid lysine, for example, which comes mostly from animal proteins, soy and legumes. Heat has an impact, but the slight decrease of lysine in toasted bread is considered negligible. (For more on vitamins and their primary food sources, see b.link/pbq4rwb. For an explanation of the amino acids and their food sources, see b.link/9tc63kb.)

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.