DEAR DR. BLONZ: I wanted to tell you how much I enjoyed your column about grilling foods. When I was much younger, I would barbecue two or three times a week using charcoal. That went on for at least 20 years. I attributed that to my developing colon cancer when I was 54. My good friend with a similar lifestyle had the same result. So, with all of that said, you didn't mention specifically the use of charcoal -- any relevance? -- D., via email

DEAR D.: Thanks for your note, and sorry you had to experience colorectal cancer. I am hopeful that you caught it early, as that can make all the difference. We all should undergo routine screenings starting at age 45 or earlier as worked out with our health professionals. The colonoscopy, a critical screening method, is not a joyous experience, but it is trivial compared to the risks generated through avoidance.

The key concern here is the formation of carcinogenic substances when fats drop on a hot surface and get transformed. These nasties can then get carried back and deposited on the food; this can occur with grills that use gas or charcoal, and it can also happen with pan-frying and broiling. When cooking outside, care should be taken to avoid inhaling smoke, especially that from fat flare-ups. When cooking indoors, there should always be good ventilation to avoid any unintended inhalation of these nasty substances, including carbon monoxide, making it important to have a sensor nearby.

Back to your question: Possible contributors were more likely what you were making and how it was typically prepared on the grill. Also involved would be the other foods on the plate and the overall quality of your diet and lifestyle. Then, in addition to those lifestyle and environmental factors, genetic issues can also raise the risk of colorectal cancer; these can be identified by DNA health tests available to consumers.

DEAR DR. BLONZ: Is there a supplement for varicose veins and bad circulation in the legs? Mine ache, itch and feel very heavy whenever I'm standing. -- P.C., Chicago

DEAR P.C.: Rather than thinking first about supplements, your priority should be to determine what is behind the problems with your legs, including that sensation of heaviness that you feel. Check with your physician to discuss these issues. It could involve something as basic as rest or muscle tone, or some other factor for which a supplement would not be of any proven value.

When faced with an unknown, it is best to learn all you can before turning to dietary supplements. This would be especially important if there are other health issues at play and medications being used.

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 was told to take a calcium supplement, but the one I purchased says to consult your doctor if you are taking estrogen, which I am. Why is that? -- J.D., Anderson, South Carolina

DEAR J.D.: Product cautions are not to be taken lightly. But for some perspective, these warnings serve the dual purpose of alerting consumers to potential concerns while affording the product's manufacturer a measure of liability protection. There are always possibilities for unforeseen interactions. When there is a known risk, or at least a suspected one, these tend to get notations on the product label or insert.

As for the particulars of your question, calcium supplements are commonly used along with hormone replacement therapy. Other ingredients in that supplement may be responsible for the caution. Get clearance from your physician, which may involve only a simple phone call.

The bottom line is that these decisions are best made with the health professional most familiar with your particular situation.

DEAR DR. BLONZ: Is there any significant difference between the protein in red meat and that found in seafood, such as shrimp? I reduced my meat intake to once a week, but I'm concerned that I'm not getting enough protein. I do a cardio workout three days a week and also work out with weights. I am interested in adding some seafood to the menu, but wondered if that protein is as good as that found in red meat. -- S.F., Phoenix

DEAR S.F.: There are minor differences between the proteins found in red meat and seafood, and these are mainly different amounts of the various essential amino acids. Both are considered high-quality "complete" proteins, in that they both contain good amounts of all the amino acids the body needs to make its protein. To answer your question, you should consider them comparable.

Scientists score proteins by looking at the types of amino acids they contain and then comparing them with the amino acids in our body's protein. Those that compare most favorably have the highest score. Egg whites (albumin) are usually considered to be the ideal protein, followed by dairy, fish, beef and poultry. Contrast this with lower-scoring vegetable proteins, such as corn, wheat and rice, which contain some protein but lesser amounts of one or more of the essential amino acids. Be aware that the protein listing on the Nutrition Facts label does not address protein quality.

Most people have no problem getting the protein they require. In fact, in this country, we tend to eat more protein than our bodies need. We also have fewer of the plant foods that can help provide the dietary fiber and valuable phytochemicals that support our health.

The key is to have a mix of high-quality protein foods and other protein-containing foods, including grains, legumes, vegetables, nuts and seeds.

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: If using olive oil in foods, are the health benefits limited to extra-virgin olive oil? We found that the flavor of the extra-virgin oil we were getting was often too strong or bitter for our taste, so we switched to ordinary olive oil. What are we missing health-wise, if anything, by not using extra-virgin oil? -- O.F., Phoenix

Dear O.F.: Many different types of olives are used to make oil, each with subtle twists on a basic flavor theme. But even oil from the same olives can vary by where and how the olives are grown, harvested and processed. (More on the different varieties of olives used to make oil at b.link/we3azd.)

The extra-virgin style will always be the most intense, as it is the least processed. Extra-virgin also contains the highest amount of the phytochemicals of that olive variety; these protect the oil that's the vital initial energy source for a developing tree if the olive was planted.

Olive oil characteristics can vary, so consider visiting a store where they do olive oil tastings. Or, you might look online for stores that offer tasting notes for their various oils. It helps to try one or more of these to find a reviewer whose tastes align with yours. The bottom line is that, irrespective of extra-virgin oil's health assets, you don't want to use it in a dish if it doesn't work. Olives, like growing conditions, can vary from season to season. Some companies blend to achieve a consistent taste for their brand; this involves blending oils from different regions to achieve the desired characteristics.

We all want any olive oil we select to work for its intended use. You might consider hosting an olive oil tasting party where the host makes the selections, or one in which guests drop off their choices ahead of time for a blind-tasting event. It can be an enjoyable event, with host and guests gaining added knowledge. (For suggestions on how to put on such an event, see b.link/xpdvp4.)

DEAR DR. BLONZ: I love spinach in salads, but heard that large consumption of spinach would cause kidney stones. Is this true -- is there any relationship between spinach and kidney stones? I would really appreciate it if you could clear up my concern. -- M.Y., New York

Dear M.Y.: Not sure what your "large consumption of spinach" is; suffice it to say it should be one of many greens, not the only one you consume. Spinach is an excellent food -- one of my favorites, as well, and is unlikely to cause kidney stones to develop in an otherwise healthy individual. (More on kidney stones at b.link/3nn8k6.)

If your body has displayed any tendency to form oxalate kidney stones, spinach would be on your "foods to avoid" list. So how to proceed? Assuming you are in good health, there is no history of kidney stones in your family, and in discussions with your physician there have been no expressions of concern that you are at risk of developing kidney stones, it seems dubious to avoid spinach on the mere chance that you "might" form a stone.

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.