Dear Doctor: I thought mushrooms were kind of a nonstarter from a nutritional standpoint, but now I read they are the best source of the antioxidants linked to anti-aging. Have I underestimated their health benefits? They're kind of icky, but I'll eat them if I have to.

Dear Reader: "Icky and slimy" was the way I described mushrooms as a kid. I would push them to the edge of my plate, hoping my mom wouldn't notice my disgust for the fungi. Eventually, however, I started to like them and now enjoy many species of edible mushrooms. They're low in calories, have a small degree of protein, are a good source of fiber and contain multiple B vitamins and selenium. But decrease aging?

It's true that mushrooms contain many antioxidants, including glutathione and ergothioneine. That seems to be where these claims start. Glutathione helps protect and repair cells damaged by everyday life, pollution and harmful influences. Although deficiency can lead to multiple health problems, it isn't known whether supplementation can help people without a deficiency. Ergothioneine is found throughout the human body and in black beans, kidney beans -- even mushrooms. Although ergothioneine has shown antioxidant properties in the laboratory, little is known of its physiological role in humans.

One recent study, likely the one you read about, measured the amounts of these antioxidants in different mushrooms. The authors found that higher levels of ergothioneine correlated with higher levels of glutathione. Maitake mushrooms had high levels of glutathione, for example, while chanterelles had the lowest amounts of both glutathione and ergothioneine. Porcini and yellow oyster mushrooms had the highest amounts of ergothioneine. Regular white, crimini and portabella mushrooms had relatively low levels of both antioxidants. Some news coverage of this study extrapolated by linking levels of antioxidants to an impact on aging.

That may be a stretch, but mushrooms do have immune-stimulating and anti-inflammatory properties. For example, mushrooms contain arginine, which has been shown to inhibit the growth of tumor cells and decrease the rate of cancer metastasis. Some edible mushrooms also contain fatty acids and lectins that decrease inflammation and may inhibit growth of tumors such as breast cancer. Further, phytochemicals in mushrooms such as indoles, phenols and terpenoids have been shown to decrease inflammation. All these compounds are potentially important because chronic inflammation can lead to cancer and vascular disease, even as inflammation and oxidation can lead to harmful effects on nerve cells in the brain.

The effects on the brain bring us to one of the biggest worries in aging: the risk of dementia. Countries such as Italy and France, which have high dietary amounts of ergothioniene, have substantially lower rates of Alzheimer's and Parkinson's disease compared to countries such as the United States with low amounts of dietary ergothionene.

Now, all this information about mushrooms and their link to health and aging is far from conclusive. In fact, it may be wishful thinking.

Yes, mushrooms contain many compounds, including antioxidants, which are good for your health, but so do many foods, such as berries, oranges, plums, grapes, kale, spinach, Brussels sprouts and broccoli. Perhaps you should simply add mushrooms to this list.

In other words, give them a try. You may find some varieties more appealing than the typical white mushrooms, and you may be surprised, as I was, that you like the taste.

(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: 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.)