Dear Doctor: Would you please explain what "grams of protein per pound of body weight" etc. actually LOOKS like on someone's dinner plate? I think a lot of readers would love to have a visual for how much protein we are supposed to be eating.

Dear Reader: We're so glad you've brought up portion size. Along with eating from a well-balanced range of food groups, it's the factor that has the greatest impact on nutrition, good health and weight control. And you're right -- there's definitely room for an "aha!" moment regarding portion size.

Protein is the major building block of our bodies. Bone, muscle, cartilage, hormones, antibodies, membranes, chemical messengers, skin and blood all need protein to function. As with so many areas of nutrition, how much protein we need is a subject of ongoing debate.

In our recent column about protein, we cited the figure of 0.36 grams of protein per pound of body weight, which is the current Recommended Dietary Allowance, or RDA. That's considered the minimum needed for all systems to function well. Newer research seems to be leaning to somewhat higher numbers. We'll keep an eye on that for you and report back if things change significantly.

As for what a protein portion looks like on the plate, it depends on what type of protein you're talking about. Poultry, fish, beef, pork, eggs and milk products fall into a category known as "complete proteins." That means they contain the essential amino acids, which are nine amino acids that our bodies need but cannot manufacture.

A serving of meat or fish is generally considered to be 3 ounces. That's about the size of a deck of playing cards. Depending on the type of meat or fish, you're getting about 20 to 25 grams of protein per 3-ounce serving. A 1.5-ounce serving of cheese has in the neighborhood of 10 grams of protein, depending on the type. That's about the size of an index and middle finger held together.

Most of the other natural sources of protein, such as dried beans, rice, legumes, seeds, grains and many vegetables, either lack one or more of the essential amino acids, or are low on them. These are considered to be "incomplete" proteins. However, as vegans and vegetarians can attest, these so-called incomplete proteins can easily be mixed together in delicious combinations that make up for their various deficits.

A serving size of cooked beans, legumes or grain is a half-cup, or about the amount that would fit into an empty cupcake wrapper. A loosely cupped hand holds about an ounce of nuts. A tablespoon of peanut butter is about the size of the first joint of your thumb. For a 3-ounce serving of tofu, which has 7 grams of protein, we return to the visual of a deck of playing cards.

Once you start paying attention, learning portion sizes becomes easier. Just be sure to take variables like fat, salt and carbs into consideration when choosing your proteins.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I've been having chest pain, and my doctor said that although I shouldn't panic, I should consider a stent. Now I read they're useless. What are my options?

Dear Reader: What you're describing is angina -- chest pain caused by decreased blood flow to the heart via the coronary arteries. Stable angina occurs with exertion, not rest, because the exertion makes your heart work harder. Unstable angina is irregular, can occur even at rest and is a harbinger of an imminent heart attack.

In 1977, doctors began to treat angina with angioplasty, which uses a balloon to open the partially clogged coronary arteries. In the 1990s, they started using stents to keep the arteries open and make them less likely to collapse. In this procedure, a metal stent is placed over a balloon so that when the balloon expands, the stent presses outward to buttress open the artery. Because these metal stents can increase the risk of blood clots, they're often now coated with a drug that prevents clots. Angioplasty has been found to reduce the risk of heart attacks and strokes in people with unstable angina.

For stable angina, the picture recently became murkier. The study to which you're referring assessed outcomes in stable angina patients with one or more coronary arteries at least 70 percent narrowed. People were excluded from the study if they'd had a previous heart attack, bypass surgery or another vessel blocked more than 50 percent but not causing symptoms. In the first six weeks of the study, participants received standard medical therapy, including blood thinners, cholesterol-lowering medication, blood pressure medications and long-acting nitrates.

After that, study subjects were randomized into a group that received a stent or a control group that didn't receive a stent. In fact, in the second group, the patients didn't even know if they'd received a stent or not. After another six weeks, all the patients underwent a cardiac stress test and an assessment of symptoms.

No difference in symptoms was found. Even an evaluation of the ability to walk on a treadmill showed no difference between the two groups. However, when given a medication to stress the heart, the stent group showed an improvement in contraction of the heart muscle as seen on ultrasound.

Similarly, a 2007 study showed no difference in death rate or heart attack rate among people with stable angina treated with angioplasty compared to those who received medical therapy. The group that received an angioplasty did report an improvement in symptoms 2 1/2 to seven years after the treatment, but it's possible the placebo effect played a role. That's because, unlike the more recent group, the 2007 study participants knew whether they'd had angioplasty.

That said, stents are not useless. They do prevent heart attacks and death in people with unstable angina, and they may benefit people with stable angina who have symptoms even on medication or who are intolerant to medication. But it seems to me that the robust benefit of stents in people with stable angina is not evident. I'd recommend talking with your doctor further; you do have a choice.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Hello again, dear readers! Your letters continue to pour in, and we are impressed by and grateful for your curiosity, kindness and your thirst for knowledge. We, too, are lifelong students and love learning from you.

-- Lawrence, a nurse anesthetist from Suffolk, Virginia, expands on the column about bringing a written list of questions to your medical appointments. He suggests maintaining a comprehensive health profile on your computer, which can easily be printed out as needed.

"I include not only medications, but a list of diagnoses, surgical history, contact info and insurance info," Lawrence writes. "The profile is about 2 inches wide by 6 inches long and fits in the front of my wallet, where it would be easily found if I were incapacitated."

-- In response to the column about Grover's disease, a condition that manifests as a rash that can often be maddeningly itchy, readers shared novel ways to deal with the itch.

A reader diagnosed with Grover's disease five years ago recommends using a thin layer of a mentholated topical ointment, like Vicks VapoRub.

"This does two things for me," he writes. "First and fabulous, the itching pain ceases immediately." He reports that the ointment also helps the rash to "dry up" and also prevents spreading, which happens when he scratches.

Another reader living with the condition, who is allergic to steroids, has found relief with a hair dryer. By using a low setting that doesn't burn or damage his skin, he reports that the warm air not only relieves the itch for several hours, but also seems to cause the rash to retreat.

-- The column about the ick factor of the traditional colonoscopy prep solution brought a ton of mail. We have reached out to some colleagues here at UCLA who use an alternative approach and will be addressing the topic again in a future column.

-- And finally, a bit more about service dogs -- or more specifically, fake service dogs. We heard from many of you about the frustration of seeing people abuse the privileges extended to genuine service animals because they want to bring their pet into a store, restaurant or theater. Brad from Naples, Florida, wrote of a plane trip during which an unruly collie brought aboard as a service dog spent the entire flight barking and lunging at passengers.

It's true that some people are taking advantage of the honor system that gives service animals carte blanche to access public places. However, just because you can't "see" a person's challenge or disability doesn't mean the dog is a mere pet. For example, some people with diabetes or epilepsy, which are mostly invisible conditions, depend on their service dogs for warning of a medical emergency.

That said, we share your dismay when poorly trained, ill-mannered or aggressive animals are passed off as service dogs. Not only is it selfish and dishonest, it's also detrimental to the reputation of true service dogs, and makes things even more difficult for their owners.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)