DEAR DR. BLONZ: I wanted to ask a few questions about calcium. Have you heard anything about the absorbability or bioavailability of calcium hydroxyapatite? I have heard arguments that it is the most available because it is a component itself of bone matter. What do you think? I have also heard that milk is not the best source of calcium for bones because of all its protein. What is that about? -- S.P., Phoenix, Arizona

DEAR S.P.: Calcium hydroxyapatite is the main calcium compound found in bones. Because it is bone, it contains the full complement of “on the job” bone minerals. Somewhere along the line, someone came up with the idea that it would be an ideal calcium supplement; just grind up cow bones, and there you have it. We must consider that calcium must be absorbed before it can be utilized for its many biological purposes, which, of course, includes the making of bones. Hydroxyapatite has yet to demonstrate any superiority as a calcium supplement. If higher absorption is the key, the best bets are calcium citrate malate or calcium citrate.

The bottom line here is that it is more important to get the calcium than spend too much time worrying over which form is best. Regardless of which form you take, it is accepted that mealtime is the best time to take calcium. But there has been some controversy about the issue of calcium supplements, so check out the article at b.link/calcium63.

You mention the issues of milk and protein, and the impact on our bones. The impact of protein on bones is complicated. Milk itself is not the issue here. The key fact is that excess protein is not stored in the body. Rather, it is converted into energy, which the body can and does store, perhaps more efficiently than some of us might appreciate.

Changing protein into energy creates a bit of metabolic refuse, and this needs to be eliminated from the body through the kidneys. That refuse has a negative charge, and animal proteins tend to create more of the negatively charged compounds. The kidneys have to pair this refuse with a positively charged escort for it to exit the body. While not the body’s first choice, calcium, a positively charged ion, can serve this purpose. Other positively charged substances to serve this purpose are found in fruits and vegetables. But if little else is around, there is always calcium in the blood, and it can get the call. The level of calcium in the blood needs to be maintained, so if calcium ends up on escort duty, more calcium gets pulled from the bones to maintain the blood level.

To summarize, some calcium can be lost when one eats a high-protein diet, but this will be more of an issue with a diet that does not contain the recommended intake of fruits and vegetables. Yet another reason for that plant-based, whole foods diet.

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 read your column pretty regularly here in the San Francisco East Bay, and had to deal with our recent power outage. I was able to have a friend take my frozen food to keep it cold, but forgot about the mayonnaise, sour cream, milk, and cream-based salad dressings. My power was out for 36 hours, and these items were only moderately cold when it restarted. What is a safe period for these types of food to be unrefrigerated? -- B., San Francisco, California

DEAR B.: I went through that same outage. It was quite disconcerting to experience this planned outage, complicated by howling winds, the very real threat of fire, and the knowledge that at any moment you might get the call to evacuate. All this with no reliable cell service. In our house, we had purchased a couple of hefty backup batteries to provide power for the fridge, and a solar panel to recharge the batteries. We could only get updates via AM radio.

With all the angst, our situation paled in comparison with those who ended up in the path of the fires and lost it all. Many others have yet to get their power turned back on. I am hopeful that these events will be a stark reminder of the need to invest in all aspects of infrastructure associated with our health and well-being, and not to wait for a tragedy to remind us what we should have been doing all along.

Stepping down from the soapbox, let me address the substance of your question. My thoughts are that in such situations, it is always prudent to toss “marginal” foods or those suspected of having been improperly stored. This would especially be the case for the items you list, as they are typically consumed without additional heat treatment that might help destroy unsafe elements.

Food safety experts say that four hours without power is the mark after which perishables should be tossed. In your case, we are talking about foods that remained in the fridge, so they would remain somewhat cold, depending on your appliance’s ability to retain its temperature. That ability is affected by the age, size and quality of the appliance, as well as each food’s location in the fridge, and how each product had been handled prior to the outage -- i.e., whether, and how often, it had been opened and kept at room temperature before being returned to the fridge.

Then, we have the questions of how often the door was opened during the outage; were bags of ice or cold-packs put in the fridge to help maintain the cold; were the containers surrounded by objects that might have helped retain the cold, etc.

Finally, there is the issue of who will be consuming those items, and the status of their immune system. This is not an exact science; I am attempting to describe a gamble with lots of variables. The omnipresent bottom line is that, where health is concerned, it is a smaller, wiser investment to toss and replace than roll the dice.

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 concerned about the dark circles under my eyes. They seem to run in my family, and I wonder if there are any vitamins, minerals or herbs I can take that might help. -- D.C., Tucson, Arizona

DEAR D.C.: Darkness under the eyes can be brought about by certain medical conditions, including allergies, dehydration, sleep difficulties and stress, and you should consult your physician if you have questions as to whether any of these might be involved.

Another common cause is the natural thinness of the skin under the eyes. The skin itself isn’t dark, but it is often thin enough to see the vascular bed underneath. This trait can indeed run in families, and its presence does not necessarily reflect any health problems. If one is fatigued, ill or under stress, the skin can become pale, and this would accentuate the darkness.

I am sorry to report that aside from using a normal, healthful diet and lifestyle to cope with life’s stresses, I am unaware of evidence showing that particular vitamins, minerals or herbs can help eliminate this problem.

DEAR DR. BLONZ: During my childhood, my grandmother from northern Italy made delicious candy from the seeds of peaches. Every fall, after we feasted on the fresh fruit, she took the seeds and fried them in butter, then added sugar till it all melted. It became the most delicious brittle candy. Now I have learned that there is poison in peach pits. Was the candy dangerous? We never got sick from it. -- L.D., Hillside, New Jersey

DEAR L.D.: It is fortunate that you did not get sick from that candy. Peach pits are not really the safest items to have in one’s diet. They, along with apricot kernels and apple seeds, are sources of a cyanide-containing compound known as amygdalin. Although a natural substance, cyanide is a very potent poison because it can effectively shut down metabolism. The body has a recovery mechanism, and as with most toxic materials, it’s the dose that determines the impact. The fact that you’re around to relate this story shows that the amount of cyanide in the peach pit brittle was insufficient to cause any obvious harm. But this is not a recipe I would pass down to future generations.

DEAR DR. BLONZ: I like to grind flax seeds and use them in my foods. I do not want them to go rancid, and was wondering if they need to be stored in the refrigerator or freezer. Also: Can fish oil capsules and other omega-3 supplements go rancid in the same way? -- E.A., San Diego

DEAR E.A.: You are correct in your approach to flax. The seed wall is designed to protect the oils within, but once the seeds have been ground, there needs to be some protection from oxidation. I would not recommend purchasing ground flax from a bulk bin, for example, where the grounds may have been sitting around for long periods of time.

If ground flax is in a well-sealed container, it should be OK at room temperature, but would do even better in the refrigerator. As regards fish oil, capsules are designed to protect their contents. If unbroken, they should be performing that function.

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.