DEAR DR. BLONZ: Most fresh potatoes are not sold right out of the field, but are stored first -- sometimes for many months. Do they lose their nutritional value in storage? -- S.G., via email
DEAR S.G.: Fresh tends to be best, but if stored under proper conditions, potatoes do quite well with little nutrient loss. Cool, dry and dark conditions are the key, with “cool” defined as a range of 45-50 degrees F. Exposure to warmth or light will cause the potato to come out of its dormancy, begin to sprout and take on a greenish tinge. Potato sprouts or green parts are NOT to be eaten.
If stored correctly, mature potatoes will keep well for up to two months. Aside from their carbohydrate content, an average-sized potato (with skin) is a good source of vitamin C and potassium, and also provides a couple of grams of fiber, several B vitamins, magnesium, iron, phosphorous and zinc.
DEAR DR. BLONZ: My reading of food ingredient labels often reveals “modified food starches” somewhere on the list. I prefer to make foods from scratch, but this is not always possible. Are these ingredients I need to be concerned about? -- W.H., Charleston, North Carolina
DEAR W.H.: A modified food starch is a complex carbohydrate that has been chemically modified to change some of its qualities. These would include texture, the ease with which the starch dissolves, and how readily the starch can be digested. Modified food starches are used in processed foods as thickeners, as formulation aids (to help maintain a desired consistency or texture), as an anti-caking agent (to help keep powdered foods free-flowing), or as a humectant (an additive that absorbs and maintains a food’s water content). Typical foods that contain modified starches include sauces, pie fillings and gravies.
Modified food starches are usually synthesized from a naturally occurring food starch, and they are not considered to represent a health risk. Those sensitive to gluten, however, should avoid foods containing modified food starches unless specifically labeled as “gluten-free,” as the starch may have originally come from wheat or another gluten-containing grain.
DEAR DR. BLONZ: My son and son-in-law both suffer from kidney stones. Can you tell me what foods they should not eat? -- A.T., Phoenix
DEAR A.T.: Kidney stones are among the most painful conditions that people can have, and they can develop for a number of reasons. There are different types, so an essential first step is for each of your relatives to work with his physician to determine the type of stones he has, and what might be responsible for them. Don’t wait; find out what is going on. Once you have this information, there will be more specific steps to take. The therapy will depend on the type of stone being formed. About the only common advice is to drink plenty of water.
There is more information on kidney stones at the National Kidney and Urologic Diseases Information Clearinghouse: kidney.niddk.nih.gov
Send questions to: “On Nutrition,” Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to firstname.lastname@example.org. Due to the volume of mail, personal replies cannot be provided.