DEAR DR. BLONZ: I am a female in my early 20s and have started taking a mineral supplement to build up calcium before I start losing it. I was wondering if there is a best time of day to take this? -- K.W., Nashville

DEAR K.W.: I applaud your strategy of working on your bones while your bone-building window is open. As a general rule, taking a calcium supplement with or after your biggest meal is best. Avoid taking more than 500 mg at a time.

Some people get their calcium from calcium-fortified beverages, such as orange juice. Recommendations regarding side effects and safety when taking calcium can be found at b.link/jffcvd5m.

Exercise and an active lifestyle play a big role in building bones -- activity tells your body that the bones are needed for work, and the body responds by building them up and keeping them strong.

DEAR DR. BLONZ: Do you have any information about the value of drinking oxygenated water, in which oxygen is infused into special water to facilitate health for those with cardiovascular disease? Could you refer me to the straight scoop? -- M.A., Hayward, California

DEAR M.A.: It's easy to burst this bubble: Our bodies are set up to get oxygen through breathing, not swallowing.

Like most gases, oxygen is poorly soluble in water, so there won't be much oxygen in a serving of oxygenated water. Consider carbonation, where carbon dioxide gas (CO2) gets dissolved in water. Generally, gas becomes more soluble in water with lower temperatures and higher pressures. Carbonation occurs when CO2 is forced into very cold water under high pressure. The container is securely sealed when the desired amount of gas has been added. This liquid looks like plain liquid in the sealed container as it sits, but CO2 bubbles will form and escape when you open the container, which relieves the pressure. Bubbles also form if the liquid warms in an open glass or when it is moved, shaken or stirred -- which increases the kinetic energy (heat), further decreasing gas solubility.

When consumed, the tiny amount of oxygen still present after the loss when the container was opened drops even further as the liquid rises to body temperature. You will experience a telltale belch as it continues warming while it travels toward your stomach. There is no basis to expect that the minuscule amount ending up in your digestive system will impact the level of oxygen delivered to your muscles or brain via the bloodstream.

Drinking oxygenated water remains an unproven concept. Misleading marketing can entice the vulnerable through the door, but there is no evidence that you get anything more than expensive water, a burp, and more containers to recycle.

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 almost 83, and often make green split pea soup using freshly bought dried split peas. I use only a small amount of salt, and ensure the peas are well-covered with cold water. I put a lid on the pot and cook them at low heat. I don't know why, but I always end up with a coating on the inside of the pot lid. I try to scrape the crust, but can't remove it without soaking and scrubbing the lid. Can you please advise me on what causes this and how I might prevent it from happening? Growing up in Chicago, I recall my family serving green split pea soup with ham hocks, and I don't recall having this problem then. -- M.F., Tucson, Arizona

DEAR M.F.: A degree of foaming is normal when cooking split peas or other legumes. A main contributor is the saponins -- phytochemicals that serve as part of the plant's microbial defenses. Saponins have a bitter taste.

Soaking and rinsing legumes before cooking can reduce the amount of saponins. Another option is to skim the foam off the water periodically during the cooking process. Bubbling and boiling can splash foam onto the lid, so more gradual heating can reduce the foaming, as can adding a small amount of oil to the cooking water.

Because water minerals can affect foam formation, your comment that you seem to be experiencing more foam today might be associated with the hardness of the water in your current location.

DEAR DR. BLONZ: I am trying to lower my weight by making small changes in my diet. One change I've made is to lower -- but not eliminate -- my carbohydrate intake, mainly breads and pasta. I've lost 5 pounds in 4 weeks. It's not a huge amount, but it's a start! My question is about the combination of rice and legumes. I've been told that the amino acids combine to make a complete protein when you eat beans and rice at the same meal. I'm confused about how the body digests this combination as a protein or a carbohydrate. Would you please clarify this for me? Should I give up my favorite brown rice and black bean recipe? Thank you. -- M., Pinole, California

DEAR M: Both beans and rice contain carbohydrates, protein (in the form of amino acids) and a small amount of fat as separate nutrients. They will be digested in the same manner, whether eaten at separate meals or at the same time.

Individually, neither beans nor rice contains all essential amino acids. But if these foods are present together, their amino acids serve as raw materials for the body to make complete proteins, similar to if you had consumed an already complete animal protein food.

I am unclear as to why you would think it necessary to forgo brown rice and black beans, which is a great example of a plant food combination that provides amino acids for a complete protein. Keep an eye on your total caloric intake, stick to healthful foods such as these, and maintain an active lifestyle, and you will continue to make strides.

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: Compared with 75% lean, would 95% lean ground beef be considered low-fat? This came up during a discussion at a burger party, and we all recorded our votes. Is one that much more healthy than the other? -- C.T., Los Angeles

DEAR C.T.: The government standard for low-fat food is no more than 3 grams of fat per serving, and neither passes that test. Some background about ground beef fat is required to make the determination, including consideration of what happens during cooking, as well as some math.

A serving of hamburger might be considered the burger itself, but given that they come in a range of sizes, especially when homemade, this can be confusing. Let's consider a serving to be one-quarter pound (4 ounces, or 114 grams) for our comparison.

Before cooking, a 4-ounce serving of 75% lean ground beef will have 331 calories, of which 28 grams (252 calories) is from fat; this represents 77% of the total calories in the serving. This serving has 18 grams of protein.

The same weight of uncooked 95% lean ground beef will have 155 calories, of which 5.7 grams (51 calories) is from fat; this represents 33% of the total calories. This serving has 24 grams of protein.

Both of these ground beefs are above the 3 grams of fat per serving benchmark for low-fat foods.

Now consider what happens during the cooking process that causes both burgers to lose water and fat. Because doneness is a factor, for our comparison, we will assume the burgers are cooked to medium.

Cooking causes the 75% lean patty to drop from 113 grams to 70 grams -- a 38% weight loss -- and it will now have about 13 grams of fat, a 54% decrease from raw. There is no significant loss of protein.

Cooking causes the 95% lean patty to drop from 113 grams to 82 grams, a 27% weight loss, and it will now have about 5.4 grams of fat, a 4% decrease. Again, there is no significant protein loss.

A medium-cooked burger from a quarter pound of 95% lean ground beef gives you more to eat -- 82 vs. 70 grams -- and provides more protein (24 vs. 18 grams) and less fat (5.4 vs. 13 grams). Still, neither meets the low-fat standard.

What is healthful depends on the rest of the food on your plate that day. There are other issues that come into play, such as where the beef came from, how that rancher feeds and treats their beef cattle and the land on which the cattle were raised. All these issues deserve consideration.

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.