DEAR DR. BLONZ: My question is about blueberries -- dried blueberries, in particular. I spent a pretty penny for dried blueberries to put on my cereal every morning until a friend told me that dried berries have no antioxidant value. Can you comment on this? And what about the antioxidant value of frozen berries? -- R.L., Berkeley, California

DEAR R.L.: Dried blueberries -- and other dried berries, such as cranberries, currants and cherries -- are great, and they have considerable nutritional and antioxidant value. I don’t know where your friend got their information, but I would consider carefully any other recommendations you get from that source.

FYI, I rotate among different types of berries to add to my cereal every morning. In season, I use fresh fruit, but off-season, I use frozen or dried. It’s a great way to start the day.

DEAR DR. BLONZ: I have read that shark cartilage can be effective against cancer, but my doctor had never heard of this and was cynical. I see it for sale at many vitamin stores, so I wonder why it is being offered. Are you aware of any evidence that shows that this works? If so, how much is needed? -- S.G., Phoenix

DEAR S.G.: I share the skepticism of your doctor. Please do not consider the presence of a health product at a store as evidence of its efficacy.

Shark cartilage gained fad fame as an anti-cancer compound because it was advertised to contain something unique that could prevent the development and spread of any cancer. The hypothetical mechanism was a substance in the cartilage that inhibited new blood vessels’ creation -- a process integral to cancer cells’ growth and spread. The evidence for all this is severely lacking. As support, shark cartilage proponents cite the fact that sharks do not develop cancer, but this has also been refuted.

While there is no evidence that it is harmful to take, please consider the insidious harm wrought by delay. Many early-stage cancers can be treated, but opting for a bogus remedy can give cancer a chance to grow -- and even to spread to the point where more aggressive treatments are required. At that point, the odds for success can suffer.

DEAR DR. BLONZ: What is the difference between pasteurization and ultra-pasteurization of dairy products? -- D.C., Lombard, Illinois

DEAR D.C.: Pasteurization and ultra-pasteurization are heat treatments designed to reduce the presence of potentially harmful microorganisms. The two differ in the amount and duration of heat used. Pasteurization heats a dairy product to 161 degrees (all temperatures Fahrenheit) for 15 seconds, while ultra-pasteurization heats the product to 280 degrees for up to 3 seconds. Immediately after either heat treatment, the milk gets rapidly chilled to 39 degrees.

The higher heat used in ultra-pasteurization results in a more shelf-stable product, which means it will have a longer shelf life. The product label will indicate which method was used. Neither process sterilizes the product, so once opened, both require refrigeration and will last about seven to 10 days.

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: For years, my blood glucose has been in the “high-normal” range. The last couple of checkups showed elevated levels, though, and after some other tests, I was diagnosed as having Type 2 diabetes mellitus. I am 65, a bit overweight, with no family history of diabetes. I was advised to lose some weight, change my diet and do more exercise. I’m not clear about insulin resistance and how it relates to the different types of diabetes, so I am interested in your thoughts. -- F.S., Scottsdale, Arizona

DEAR F.S.: Glucose, the building block of carbohydrates, is a primary fuel for the body. It is the brain’s preferred fuel, and the only one that red blood cells can use. Entire body systems exist to help maintain blood glucose, but these systems don’t always work perfectly.

During digestion, dietary carbohydrates get broken down to glucose, which is actively absorbed into the bloodstream -- at which point it is often referred to as “blood sugar.” Glucose has a hard time getting into cells on its own. The missing factor is insulin, the hormone produced and released by the pancreas that serves as a passport to get glucose into most cells. (Insulin doesn’t help get glucose into the brain -- that’s a different story.) Once in the cell, glucose provides energy for all work, including muscle contraction, biosynthesis and repair. Once cellular energy needs are satisfied, extra glucose gets turned into lipids (fat), the most concentrated form of energy in the body. Packaged as triglycerides, these travel to storage in our fat cells.

Diabetes is present when there’s insufficient insulin to get the glucose out of the bloodstream and into the cells. Type 1 diabetes is when the pancreas is unable to produce and release insulin. In such cases, replacement insulin is given, usually by injection. More common is Type 2 diabetes; this occurs when the pancreas can still produce and release insulin, but can’t keep up with the demand, so blood glucose levels remain elevated. Treatment can include diet and lifestyle adjustments or medications to stimulate the pancreas to release more insulin. Type 2 diabetes used to be known as “adult-onset” diabetes because it was seen mainly in adults, but now it is prevalent in children, as well.

Here’s the connection between Type 2 diabetes and weight: As fat cells increase in size, they tend to become less sensitive to insulin. This insulin resistance means that the body needs more insulin to clear the same amount of glucose from the bloodstream. Obesity, in essence, can overwork the pancreas until it becomes unable to keep up. Between 80 and 90 percent of those with Type 2 diabetes are obese. This also helps explain why those with this type of diabetes often experience dramatic improvements when they lose some pounds and change the way they eat.

There are short- and long-term health risks if blood glucose remains elevated. The bottom line with any diabetic condition is to keep the glucose within normal limits. This can be done with diet, exercise and medication, along with regular monitoring of blood glucose levels. For more on managing diabetes, see b.link/wb6c3.

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 have heard that harmful changes can occur in water bottle plastic during heating in a microwave. While I don’t microwave these bottles, I have been opting to reuse them after washing, drying and refilling them with fresh water. After this, they are put in the refrigerator. As part of my treatment, I run the bottle’s neck under an instant hot water tap to sanitize it (even though I am the only one using these bottles). Would this be considered heating the plastic and therefore harmful? I drink lots of water and reuse plastic water bottles for their portability. I want to keep doing this but want your thoughts on this subject. Thank you. -- D.M., Phoenix

DEAR D.M.: Most commercially packaged plastic water bottles are designed for a single use. These bottles, or any plastic, for that matter, should not be put in a microwave unless it specifically states that it is microwave-safe. There is an underlying concern regarding re-use that consumers will not adequately clean and dry the containers between uses. There are bacteria on our hands and mouth, and they easily get on and in bottles when used. The failure to clean and dry properly makes the bottle a convenient breeding ground for potential problems. Consider also that the narrow mouths of commercially packed water bottles make them challenging to wash and rinse. My thought is it’s best to avoid this type of re-use. If, however, you are still planning to reuse plastic water bottles, here are some reasonable strategies -- but these are not a guarantee of safety.

Give the bottle a good visual examination to make sure it is not discolored, cracked or damaged. Using a safe water supply, wash your hands thoroughly to control for the presence of bacteria. Then carefully clean the bottle and scrub with hot, soapy water using a bottle brush; rinse, and air dry. Avoid sharing bottles where the contents come in contact with the hands or mouth, allowing the transfer of bacteria. If needed, label the bottles for easy identification. Keep the container out of the sun, away from heat. I am uncertain whether the hot water tap would cause any problems. Limit re-use to a few times, then send the bottle off to be recycled.

A better option would be to use water bottles designed for re-use. Stainless steel containers would be on the top of the list, and you can find some that are double-walled to help maintain the internal temperature. There are also reusable plastic bottles. Many reusables have larger openings to facilitate cleanings between use. If opting for a plastic bottle, best to verify that it does not contain BPA (bisphenol A), an industrial chemical linked to several health problems. The FDA has banned the use of BPA in containers used for babies and children.

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.