DEAR DR. BLONZ: I know that osteoporosis runs in my family, but I have an issue with lactose, so I have to be careful what I eat. I have been using a calcium-based multimineral supplement with vitamin D to be sure I get all essential nutrients. I'd like information about a product made with red algae calcium, as this is promoted as a better form of calcium that also comes with all other minerals needed to make bone. -- L.M., Aurora, Illinois

DEAR L.M.: Understanding that osteoporosis may run in your family is essential to knowing what steps you should be taking. (Determine if osteoporosis runs in your family at b.link/g2x764yu.) This diagnosis will also help your children know if they're potentially at risk so they can adopt beneficial diet and lifestyle behaviors.

Calcium is primary for healthy bones and teeth, but magnesium, silicon, boron, copper, zinc and manganese are also needed, along with vitamins D, K and C for mineral absorption and bone formation. Phosphorus is vital for bone health, but the intake in the U.S. usually greatly exceeds our requirements.

When taking a calcium supplement, it is best to avoid more than 500 mg in a single dose. Be sure to check that your calcium (or any) supplement won't interfere with any other medications you take. (Check with the prescribing physician and your pharmacist, or use the "interaction checker" at drugs.com.) For information on preventing osteoporosis with calcium, see b.link/4rrf6erb.

The red algae calcium you mention is a crystalline structure that's basically calcium carbonate -- limestone of the sea, if you will. It is unclear how any product containing only that substance can claim to have all the minerals in the correct proportions for bone growth. I predict a check of the ingredients statement and Supplement Facts label will reveal other components in the product. Calcium carbonate from any source is best taken with food, as the acid environment in the stomach is needed to help break it down to make the calcium bioavailable.

You mentioned you have lactose intolerance, so you may have avoided certain dairy products. Dairy, while not essential for bone health, does provide a convenient package of nutrients. Look for lactose-free dairy products now available, including milk, yogurt and kefir.

Being active is helpful, relying on the "use it or lose it" approach for bones and attached muscles. Weight-bearing exercises, such as walking, stretching and other floor exercises, can help. If osteoporosis, or its forerunner, osteopenia, is already on the scene, there are strategies, medications and periodic monitoring to assist. Discussing all this with your health professional and physical therapist is best. Find additional information on osteoporosis at b.link/2bzy977z.

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 questions about foods sold in plastic containers at my local store. Can a microwave be used to defrost chicken and beef broths in these containers? These foods are produced in small quantities, sold only at this store, and have no markings aside from a label indicating the food inside. Should I be concerned about plastics leaching into the food? -- B.B., Portland, Oregon

DEAR B.B.: Many different materials are used in food packaging, and there may be cause for concern if a substance migrates from the packaging into the food it contains. These are referred to as incidental food additives, and are regulated by the Food and Drug Administration. Attention is required if a food-packaging substance is found to be harmful, but there should also be concern if the packaging affects the food's quality, appearance or shelf life. Two concerns with plastics are bisphenol A, also known as BPA, once common in can-lining materials and plastics, and plasticizers known as phthalates. (More about BPA at b.link/dzukfd, and phthalates at b.link/skx9fz5e.)

Your local store packages its minimally labeled foods in plastic containers, then stocks them in their freezer for sale. Foods prepared in a retail establishment and sold only in that establishment are exempt from the requirement to display nutrition labeling. (For more on this, see b.link/6ex3bwrr.)

But that does not absolve you of the need to know how to treat these foods and their containers appropriately -- especially as they may be sold in single-use containers unsuitable for the microwave.

Check for a "microwave-safe" symbol on the carton or label before putting that container in the microwave. "Microwave-safe" is usually an icon with horizontal wavy lines. (For examples of food and equipment symbols, including those signifying "microwave-safe," see b.link/hdsuug2b. For more on general microwave safety, see b.link/js6iw9yw.)

If you don't see the "microwave-safe" symbol, it's best to assume the container is not microwave-safe. What to do with that store-packaged frozen broth? Defrost it in your refrigerator. You can also use a brief hot-water bath to loosen up the contents and then transfer it to a designated microwave-safe container for the rest of the defrosting in the fridge.

If the container has a symbol of a 5 in a triangle, often with a "PP," it is made from polypropylene, which is generally considered microwave-safe. Still, it's best to find those squiggly, microwave-safe lines. The responsibility is on the consumer to check with the store to verify that they use microwave-safe containers. You can encourage the store to post information about the containers they use.

One final point: Containers, particularly plastic ones, do not have an indefinite life span. Discard single-use containers after the contents are gone, and toss any plastic container if it shows signs of cracking or discoloration.

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 had to stop my caffeine intake due to a health condition. It took a few days to stop the annoying headaches, and I wondered what caused them. Things have now settled, but I do miss my coffee. I have a question about a caffeine-free energy drink: The ingredients list shows "guarana," which has me wanting some clarification before trying it. Thanks for any advice you might provide. -- T.I., San Jose, California

DEAR T.I.: The headaches you experienced relate to the way caffeine works: how the body adapts to its chronic presence, and what happens with abrupt withdrawal, which is what you went through. In addition to caffeine, a key biochemical in this scenario is adenosine, a compound found in all living cells that plays many roles and is part of the genetic building blocks of DNA and RNA. As a neurotransmitter, higher levels of adenosine cause feelings of sleepiness. Receptors on cell surfaces bind to adenosine to make this happen. Caffeine blocks the adenosine receptors, which keeps us alert. After days of regular caffeine intake, the body compensates by adjusting the number and sensitivity of its adenosine receptors. Not everyone responds to this process with the same efficiency, which explains how some people can consume coffee with dinner without it affecting their ability to fall asleep at night.

When a regular caffeine user abruptly stops, the body becomes hyper-responsive to adenosine because caffeine is no longer present. It is believed this is responsible for the withdrawal headache and other discomforts associated with the sudden absence of caffeine. People who stop their regular caffeine consumption when fasting for blood tests, medical procedures or religious holidays know this sensation. Consuming caffeine, of course, would reverse it, but that's not always an option. It has been suggested that continued caffeine consumption may be as much about avoiding the withdrawal effects as any enjoyment of the caffeinated beverage itself. As a coffee drinker who enjoys my morning brew, I find this a bit disingenuous, but I acknowledge a bit of subjectivity here.

As for your energy drink: Guarana (Paullinia cupana) comes from the seeds of this South American climbing shrub. Guarana seeds have a high concentration of caffeine -- more than twice that of coffee beans, the kola nut or cacao (cocoa), which makes it a useful ingredient in energy drinks. Often referred to as guaranine, or natural caffeine, guarana is misleadingly characterized as "caffeine-free." The seeds of the guarana shrub produce caffeine as part of their phytochemical defense against insects and animals dining on the plant and its seeds. For these tiny natural poachers, the level of caffeine in one seed can be deadly, but our size provides us with greater tolerance. Marketing guarana as "caffeine-free" is deceptive. Glad you checked things out.

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.