DEAR DR. DONOHUE: Exactly what is the pneumonia shot? Who is supposed to get it? How often do you have to take it? – S.T.

ANSWER: Pneumonia is lung inflammation, and its causes are many, some seldom thought of. Noxious and poisonous gases can cause pneumonia. If digestive juices trickle into the airways, they can cause another kind of pneumonia, one that often happens to elderly people confined to their beds. Viruses cause infectious pneumonias, as do bacteria. Fungi can do the same. The only thing these disparate causes have in common is lung inflammation – pneumonia.

For older people, one-third of all pneumonias come from a bacterium by the name of pneumococcus (NEW-moe-KOK-us). The resulting pneumonia is pneumococcal pneumonia.

Before the antibiotic era, it was one of the leading causes of death for older people. It can still kill, even now with the availability of powerful antibiotics.

This is the pneumonia that the pneumonia vaccine wards off.

Everyone 65 and over should have this shot. Many favor giving it to everyone 50 and older. Doctors urge all those, regardless of age, who have less-than-robust immune systems to get the shot. That includes people taking chemotherapy, those infected with HIV, many cancer patients, and on and on.

When to get a repeat shot is a matter of some contention. The institution that is the last word on vaccines says that a booster shot should be given five years after the first shot if a person had the first shot before 65.

DEAR DR. DONOHUE: I am in my so-called golden years. Because I have chest pain, my doctor had me get an ultrasound picture of my heart. It shows that I have mitral valve prolapse. My doctor dismisses this as nothing and says it does not explain my chest pain. I don’t like the sound of it. Just how serious is it? – K.R.

ANSWER: The mitral valve lies between the left atrium (the upper left heart chamber that gets oxygen-loaded blood from the lungs) and the left ventricle (the lower left heart chamber that pumps oxygenated blood to the entire body). It keeps blood from flowing back into the left atrium when the left ventricle contracts.

A prolapsing mitral valve is one that billows upward into the left atrium when the heart contracts. If there is no leak of blood resulting from the prolapse, then the condition is most unlikely to cause chest pain.

A number of erroneous ideas of mitral valve prolapse have circulated since it was first described. One is that more women than men have it. The condition is gender-neutral. In the early days, it was thought to affect as many as 15 percent of the population. Not so. One percent or 2 percent is a more realistic estimation.

People interested in learning more about heart valve problems can order the pamphlet on that topic by writing: Dr. Donohue – No. 105, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.50 U.S./$6.50 Can. along with the recipient’s printed name and address. Please allow four weeks for delivery.

Perhaps other tests will reveal the nature of your chest pain.

DEAR DR. DONOHUE: Last week I visited my dentist and got the surprise of my life. He had me look at my tongue in the mirror. I was shocked. It was shiny red with white furrows. He told me it would go away. When he asked me if any foods bothered it, I said no. Now I remember that bananas cause a slight burning of my tongue. What is this? – D.D.

ANSWER: It’s geographic tongue, so called because the tongue looks like a geographic map with narrow white hills and flat red valleys.

The tongue is covered with minute projections – papillae. In geographic tongue, the papillae are shed, and that produces shiny red patches whose raised borders are white.

Hot or spicy foods can bother some people with the condition. So can bananas. They contain homovanillic acid, which irritates the geographic tongues of a few people. The condition leaves on its own.

DEAR DR. DONOHUE: I am lying in a hospital bed, recovering from acute pancreatitis. No one here will answer my questions, so I am writing to you. How did I get this? Does it ever come back? – L.J.

ANSWER: The pancreas has two important jobs. One is to provide insulin, the hormone that lowers blood sugar. The other is to produce enzymes that digest food so it can be absorbed.

Pancreatitis is a very painful inflammation of that organ. For some, it can be lethal. For most, it is a torture, but not a life-threatening one.

The inflammation can come about from a gallstone that blocks the pancreas’s drainage duct. The pancreas and the gallbladder share a common duct. Alcohol can irritate and inflame the pancreas. High blood triglycerides (fats) can do the same. An injury to the gland, such as one that comes from an auto accident, is another cause. Viral infections of the pancreas are on the list of causes, as are some medicines.

You appear to be making progress. You can anticipate a full recovery. About 10 percent of patients, however, have to contend with chronic pancreatitis, an inflammation that lingers on and on.

DEAR DR. DONOHUE: Is there any validity to the notion that adding coconut oil to one’s diet will aid in weight loss? Or is it a fad or perhaps harmful? – S.S.

ANSWER: I have not seen or heard that coconut oil takes pounds off the body, and I cannot come up with an explanation why it might.

Coconut oil has a high concentration of saturated fat. It was, therefore, not considered to be a heart-healthy oil. Now there are doubts about whether coconut oil really is detrimental to the heart and arteries.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475.