Sunday, February 20, 2011

Wellness Questions: Aspartame, Vitamin D and More

Questions and Answers From ;
The Berkeley Wellness Letter
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Q: Can the artificial sweetener aspartame cause depression? I know a psychiatrist who tells people to avoid it.

A: No well-designed human studies have ever found that aspartame causes neurological or psychiatric problems, including migraines, depression, insomnia, or memory loss. Hundreds of studies have exonerated aspartame. In 2007, for example, a massive review (500 studies) by a panel of experts from medical schools and research institutions in the U.S., Britain, and the Netherlands found no evidence that aspartame has negative effects in the body or mind, even when consumed at high levels.
It’s true that this review was funded by a Japanese company that makes aspartame, but the company did not have any influence on the published results, which appeared in Critical Reviews in Toxicology, a respected journal. One small and poorly controlled study in 1993 did conclude that people with mood disorders should not use aspartame, but this was the sole study with such findings. There were only eight people in the treatment group, and five in the control group—not enough to provide statistically valid conclusions. Some went into the study believing they were prone to adverse reactions to aspartame. The trial lasted only 20 days. Despite its dubious quality, the psychiatrist who conducted it wants the Senate to pass legislation rescinding the approval of aspartame. Of course, this has generated a lot of publicity.
Aspartame remains controversial, in spite of clear evidence that it is safe. Its chief ingredients, phenylalanine and aspartic acid, are amino acids that occur naturally in foods and in the body. As the warning label states, people with the rare genetic disorder phenylketonuria, which keeps them from properly processing phenylalanine, should avoid aspartame as well as foods rich in this amino acid.


Q: Are sebaceous cysts dangerous? Should I have them removed? How are they different from lipomas?

A: These lumps just beneath the skin, properly called epidermal cysts, are common and harmless. The most important thing is to check with a doctor to make sure they are cysts, and not something more serious.
Typically on the head, neck, or torso, the cysts are firm, round, and movable, and grow slowly, sometimes to an inch or more in diameter. They’re usually caused by injury to a hair follicle or some other damage to the skin. They are filled with fat and keratin, a greasy, cheeselike substance.
If a cyst is very visible or becomes infected, or if you are bothered by it for any other reason, it can be surgically removed. This is a simple procedure, but usually requires stitches. If it is simply drained, it will probably grow back.
Lipomas can look like large cysts, but are benign fatty tumors. They seem to run in families and also grow slowly; they can occur inside the body as well. A doctor will often be able to tell you whether you have a cyst or lipoma by its look and feel. Lipomas don’t need to be removed unless they are unsightly or uncomfortable.

Q: How long are you contagious when you have a cold?

A: As a general rule, adults with a cold will be able to infect others one day before symptoms appear, and up to five days or so after becoming sick. Infants and children are able to transmit these viral infections for seven days or longer. The precise number of days for transmission can vary from person to person, and also depends on the length of the illness. Those in poor health tend to get infected more easily. Children are also more likely to catch (and transmit) colds.
Cold viruses, abundant in nasal secretions, are mainly transmitted via hands. When you blow your nose, touch your face, or wipe your eyes, the virus transfers to your hands, and then to whatever or whomever you touch. If you contaminate a telephone, the next person who uses it may catch your cold. To avoid spreading or catching a cold, the most important precaution is to wash your hands often and well. Hand sanitizers are a good option when you’re not near a sink.
Coughing and sneezing can also spread germs, of course. If you don’t have a tissue, instead of sneezing or coughing into your hand, do it into your arm or shoulder, thus avoiding contaminating your hand.
If you think you are getting sick, limit your contacts. Don’t hug and kiss. If you’re around someone who is sick, stay at least three feet away. Airborne cold viruses can’t travel much farther than that. Don’t share drinking glasses, utensils, phones, or towels.
Flu viruses may not travel in exactly the same way as cold viruses, but your best bet is to take these same precautions to avoid transmitting or catching the flu.

Q: Is the vitamin D you get from being in the sun or a tanning salon better than what you get from a supplement?

A: No. Whether you get vitamin D from sun exposure or from supplements, blood levels of the active form of the vitamin rise similarly, and other effects in the body are the same. Still, some websites claim that it’s better to get vitamin D from the sun or tanning beds. Not surprisingly, many of them sell or promote tanning beds.
Vitamin D is unique in that your skin manufactures it when exposed to the sun’s ultraviolet (UV) rays. Exposing your arms and legs to the sun for just 10 or 15 minutes two or three times a week can produce substantial amounts of D, though this depends on the time of day, season, weather, how far north you live, how dark your skin is, and your age; older people produce less D from the sun. Few foods provide D, so it’s hard to get adequate amounts from food alone—especially not the levels many experts are now recommending for bone health and a variety of potential benefits.
Since exposure to UV radiation, whether from the sun or tanning beds, can cause skin cancer, it’s safer to get vitamin D from supplements. One exception: if you have certain rare intestinal absorption problems, you may not be able to absorb oral vitamin D well and may need to get it by injection.
Despite claims made by the tanning industry, tanning-bed sessions provide much more UV and expose more skin surface than is needed to produce adequate vitamin D. Maximum possible synthesis of D occurs before the skin reddens, and thus longer exposures add nothing to vitamin D stores, according to a review in the Journal of the American Academy of Dermatology in 2005.
And by the way: When you read that humans are "designed" to get their D from the sun, remember that this made sense hundreds or thousands of years ago when people rarely lived past 40, usually not long enough to develop skin cancer.

Q: I’ve seen nutritional supplements with omega-3s marketed for dry eyes. Do they work?

A: Supplement makers are basing their claims more on theory than on solid evidence. Dry eyes can be due to several factors, including age, dry climate, prolonged computer use, and Sj√∂gren’s Syndrome (an autoimmune disease). TheraTears is an omega-3 supplement made with a blend of flaxseed and fish oil. According to its website, it "works from the inside" to "support healthy tear production," among other claims. Another supplement with omega-3s for dry eyes is MaxiTears Dry Eye Formula.
There are several possible connections between omega-3 fats and dry eyes. Inflammation is thought to play a role in dry eye syndrome, and omega-3s have anti-inflammatory effects. Some researchers think that omega-3s may also promote production of an oily substance that helps prevent evaporation of the tear film.
Studies on omega-3s as a treatment are limited. Data from the large Women’s Health Study show that women with a higher intake of omega-3s were less likely to have dry eye syndrome. And a study in 2008 from Northwestern University found that omega-3 supplements (made from flaxseed oil), taken for more than a year, improved dry eye symptoms caused by blepharitis (eyelid inflammation).
If you have dry eyes, you can try an omega-3 supplement to see if it helps—or simply eat more fish. It’s not known what formula or dose would be most effective. And there’s nothing magical about supplements sold specifically for dry eyes—though they cost more than a simple generic omega-3 product. A better reason to consume more omega-3s, particularly from fish, is for heart health.

Q: Can soaking in water with Epsom salt relieve muscle soreness or arthritis?

A: There’s no evidence that it is effective. Epsom salt is hydrated magnesium sulfate and was traditionally formed by the evaporation of mineral waters. It was discovered in Epsom, England, in the 17th century and has been used as a folk remedy—notably as an anti-inflammatory soak—ever since. It’s the warm water that helps relieve arthritis symptoms, not the Epsom salt.
Spas often promote soaking in various types of mineral waters for health benefits, but absorption of minerals through skin is very limited, so the curative power of minerals—assuming they have any—would also be very limited.

Q: Does gargling with warm saltwater help a sore throat? Can it prevent one?

A: Many people find it helps a sore throat, at least a little, though scientific proof is lacking. Gargling with any solution—even water mixed with sugar or corn syrup—may temporarily relieve dryness and be soothing. Gargling won’t shorten the duration of your sore throat, though. And a better way to keep your throat moist when you’re sick is to drink plenty of water or other fluids.
As for gargling as a preventive, research is limited. A Japanese study in the American Journal of Preventive Medicine in 2005 did find that a simple tap water gargle, done at least three times a day, prevented colds by 40% in healthy volunteers over 60 days, compared to a group that didn’t gargle. And those who got a cold had less severe bronchial symptoms. Part of the benefit may come from the chlorine in the water, the authors noted.

Q: Do certain foods cause hives?

A: Sometimes, but many other things can also cause them. Hives (the medical name is urticaria) are an allergic reaction causing red or skin-colored itchy welts that may last for several minutes or hours or even days.
Besides foods, hives may be triggered by medication, cosmetics, pollen, or animal dander. Less often, heat, cold, physical pressure, or sunlight may bring on an outbreak. Emotional stress or certain diseases may also trigger hives.
The remedy involves recognizing the trigger—if you can—and eliminating it. Think of recent changes in your life: a new food, drug, or cosmetic. Shellfish, strawberries, chocolate, tomatoes, eggs, wheat, dairy products, and nuts are some common culprits. If hives appear after you begin taking a new medication (penicillin is a classic trigger), let your doctor know right away. If your hives are accompanied by difficulty breathing or swallowing or by wheezing, get emergency medical care.

Q: Is it true that eating lots of green vegetables interferes with anti-clotting drugs such as Coumadin? My doctor told me to cut back on foods rich in vitamin K, but I read about a study calling this a myth.

A: If you are taking an anticoagulant drug, you should follow medical advice about your intake of foods rich in vitamin K, along with supplements containing it. But while it’s true that vitamin K from any source can reduce the effect of warfarin (brand name Coumadin), that does not mean you need to avoid foods rich in the vitamin. Just keep your intake of such foods relatively constant—that is, don’t eat huge servings one day, and none the next.
You should know which foods contain a lot of vitamin K. These include dark leafy greens such as kale, collards, and spinach, as well as broccoli and Brussels sprouts. If you take supplements, check the vitamin K content and ask your doctor if they are okay. Some calcium supplements contain vitamin K. Though some sources say that tea has lots of the vitamin, brewed tea actually contains none.
You may have read about a study published years ago by Dutch researchers in the journal Blood, which found that vitamin K from vegetables has little effect on anti-clotting drugs. But the study was done on healthy young people, and the conclusion was that people on anticoagulants should keep their intake of vitamin K adequate and constant. The best plan is to discuss your diet in detail with your doctor and make sure that the drug dose you are taking is producing the desired results.

Q: You once advised that aloe juice has no health benefits and warned about its unwanted laxative effects. But ads for aloe juice say the laxative has been removed and claim many health benefits. Who is right?

A: It’s true that the chemical in natural aloe that acts as a laxative is often removed by manufacturers, but that doesn’t mean that drinking aloe juice is healthful.
The claims that aloe juice has countless health benefits—good for everything from hair loss and fatigue to cancer, bad breath, and weight loss—are not backed up by scientific research and are advanced only by marketers. Recent studies have looked at the juice as a preventive for kidney stones and as a treatment for irritable bowel syndrome and inflammatory bowel disease, but the evidence is not convincing. Even if it did do some good, you can’t tell how much aloe is really in these juices.
On the other hand, there are reports of liver and kidney damage (including kidney failure and death), abdominal pain, and reduced potassium levels from aloe consumption. Aloe can also interact with anti-clotting drugs. Pregnant and breastfeeding women, as well as children, should avoid aloe juice.

Q: I see "sugar alcohol" listed on some food labels. What is this?

A: Also called polyols, sugar alcohols are reduced-calorie sweeteners used in many "diet" foods—from candies and jams to baked goods and ice cream—as well as in sugar-free gums, cough drops, mouthwashes, toothpastes, laxatives, and other products. Small amounts are found naturally in plant foods.
Though they resemble sugars and alcohol in chemical structure, sugar alcohols are actually carbohydrates that the body does not fully digest. Thus, they provide fewer calories (0.2 to 3.0 per gram) than sugar (4 per gram). They are not alcoholic. You can usually identify them by their "-ol" endings—as in sorbitol, xylitol, mannitol, maltitol, and erythritol, for example—though isomalt and hydrogenated starch hydrolysates are also sugar alcohols. Added sugar alcohols are always listed by name in the ingredients. If a product makes a "sugar-free" or "no sugar added" claim, however, sugar alcohols must be included in the Nutrition Facts panel, under Total Carbohydrate.
Because they are slowly and incompletely absorbed, sugar alcohols have less effect on blood sugar—so, in moderation, they are helpful for people with diabetes. They don’t promote cavities, either. And with fewer calories, sugar alcohols may help in weight control, though foods that contain them are not necessarily low-calorie (or healthful), and none are calorie-free.
A downside is that large amounts can cause gas, bloating, and diarrhea, since bacteria in the intestines ferment what is not absorbed. And you may inadvertently consume too much, since they are in so many products. Some, but not all, products carry a warning not to exceed a certain amount.

Q: What do you think of the drink kombucha?

A: Not much. The fermented tea made headlines in the 1990s, when proponents claimed it detoxified the body, increased energy, and cured everything from AIDS to cancer. When clinical studies failed to support those assertions, kombucha’s star dimmed and little more was seen of this brew, which is essentially black or green tea fermented with a culture of yeast and bacteria.
Interest in the vinegary beverage, which has a slight fizz and alcohol buzz, has perked up again lately. The health claims continue, but good studies in humans are still lacking. The drink largely remains a cottage industry, and is often homemade—in which case, batches may be contaminated with molds, bacteria, and lead. In rare instances, kombucha has been linked to lactic acidosis, a life-threatening reaction.
Commercially made kombucha is growing in popularity as well, though not without some controversy, too. Last year at least two manufacturers removed their kombucha beverages from store shelves over concerns that they contain too much alcohol.
We can’t recommend kombucha, whether it’s homemade or store-bought. You should especially stay away from it if you want to avoid alcohol, have a compromised immune system, or are pregnant or nursing.

Q: Is poultry fat healthier than fat from red meat? Or is poultry better merely because it’s easy to remove the fat, which is concentrated in the skin?

A: Yes and yes. Poultry usually has less fat and thus fewer calories, especially when the skin is removed. In addition, chicken fat has less saturated fat and more polyunsaturated fat compared to beef fat. Saturated fat tends to raise blood cholesterol, though the saturated fat in both beef and poultry is largely composed of stearic and palmitic fatty acids, which may have a neutral effect on blood cholesterol. Polyunsaturated fat tends to lower cholesterol. Nevertheless, neither chicken fat nor beef fat should be considered "good" fats.
Removing the skin from chicken or turkey can cut the total calories by half. Skinless breast meat is leanest. Without skin, dark-meat chicken (such as thighs or wings) has two to three times more fat than breast meat—and 25% more calories. In fact, some well-trimmed, lean cuts of beef and pork (look for the word "loin" or "round") have no more fat, ounce for ounce, than skinless dark-meat chicken.


Q: Since your last article on Cold-fX a few years ago, has there been any more evidence that it helps prevent colds?

A: Not anything to hang your winter hat on. Much of the research on Cold-fX—a patented, standardized extract of North American ginseng root (Panax quinquefolius)—remains preliminary. In recent years, a few more studies have been completed, but none are published and so cannot be evaluated.
Still, based on older published studies, there’s a glimmer of hope that Cold-fX may help against colds and flu when taken daily over several months. Health Canada, which functions like the FDA, allows the claim that Cold-fX “helps reduce the frequency, severity and duration of cold and flu symptoms by boosting the immune system.”
Keep in mind, there’s no evidence that Cold-fX works if you start taking it once you get symptoms—even at the higher doses marketed by the company for this purpose. And it won’t prevent all colds. Cold-fX seems safe, though larger studies are needed, and there’s some question about possible interactions with certain drugs (such as the blood thinner warfarin) and potential problems if you have various health conditions (such as an autoimmune disorder).
Cold-fX is available in the U.S. only over the Internet. A month’s supply is about $30 (not including shipping), which adds up if taken continually, as directed.

Q: Are caffeinated beverages dehydrating? Do they count towards my eight-a-day glasses of water?

A: Many people think they can’t count coffee, tea, and colas as part of fluid intake, because caffeine promotes urination briefly. But you don’t end up with a net loss of water from drinking moderate amounts of caffeinated beverages. In other words, they don’t dehydrate you.
For instance, in a study from the University of Nebraska Medical Center a decade ago, healthy adults showed the same "hydration status" (as determined from urine analysis and other tests) when they drank caffeinated colas and/or coffee as when they drank only water and/or fruit drinks. And in its 2005 report on water needs, the Institute of Medicine (IOM), which advises the government about health issues, including dietary intakes, concluded that "caffeinated beverages appear to contribute to the daily total water intake similar to that contributed by noncaffeinated beverages."
In any case, it’s a myth that you need to drink eight glasses of water a day. There’s no scientific backing for this rule. The IOM report confirmed this, too. People normally get enough fluids by drinking when they’re thirsty—though older people should drink water before they get thirsty, especially in the heat, since thirst is a less reliable indicator as we age. And other beverages besides water (including caffeinated ones), as well as foods (such as fruits and vegetables), help meet fluid needs.

Q: Can you drink too much water?

A: Drinking too much water is seldom a concern. The body does a good job of regulating fluid intake and output. It’s safe to drink about a gallon (16 cups) a day. You probably shouldn’t exceed two gallons.
A problem called water intoxication (hyponatremia) can occur in marathon runners and other endurance athletes, people working for long hours in the heat, or even those dancing at all-night parties, usually under the influence of illegal drugs. Caused by loss of sodium from sweating during strenuous exertion, combined with overconsumption of water, water intoxication can produce nausea, fatigue, and stupor, and even coma and death. But this is not an issue if you simply drink plenty of water in the course of a normal day.

Q: When you discussed poultry safety last month, why didn’t you mention washing the raw birds?

A: The USDA advises cooks not to rinse raw poultry (and meats), since rinsing can easily spread bacteria from the poultry to the sink, countertop, utensils, and other foods. Raw poultry often contains Salmonella or Campylobacter bacteria, leading causes of food poisoning. Proper cooking destroys the bacteria.
If you find the idea of cooking (and eating) unwashed poultry unappealing, go ahead and wash it. But minimize the risk of cross-contamination. After handling raw poultry, scrub your hands thoroughly with warm water and soap. Plain soap is fine, you don’t need antibacterial brands. Wash the sink, faucets, and countertops—anywhere the juices might have splattered. Sponges used for the poultry juices can be washed in the dishwasher, soaked in diluted bleach, or microwaved for two minutes. Better yet, use paper towels for cleanup.

Q: A routine CT scan of my coronary arteries revealed extensive calcium deposits. My doctor said these can trigger a heart attack. Could this have been caused by calcium I’ve consumed? Is there any way to remove the calcium?

A: There’s no reason to think the calcium you get from food or supplements increases calcium deposits (calcification) in plaque in coronary arteries and other blood vessels.
Coronary calcification has been linked to higher cardiovascular risk. Calcium is deposited in plaque as part of the atherosclerosis process, and as such is caused largely by chronic inflammation in the blood vessel wall, not by high levels of calcium in the blood. In any case, the body is very good at regulating calcium in the blood (except in people with certain metabolic and/or kidney conditions). Calcium in the blood does not simply build up in artery walls. Nearly all studies have found that calcium supplements do not affect arterial calcification or the risk of heart disease.
It’s not known what steps can reduce arterial calcification—other than the advice for reducing atherosclerosis, such as intensive dietary changes and weight loss. Some studies suggest that cholesterol-lowering statins may slow the progression of calcification, but drug therapies have yielded inconsistent results overall. A study from Tufts University in 2009 found that high doses of vitamin K may help slow calcification. But it’s too soon to recommend K supplements for this purpose. If you’re on an anticoagulant such as warfarin, you should avoid them.
By the way, we don’t recommend routine screening of healthy people for calcification, which is done with special CT scans, even though some cardiologists promote it for those at higher risk for heart disease. Such screening is still being debated because it’s unclear how much information it provides for predicting heart disease beyond an evaluation of standard risk factors.

Q: What is a panic attack, and how can I be sure it isn’t a heart attack? How is it treated?

A: A panic attack is a sudden surge of fear and anxiety that usually comes out of nowhere. Symptoms may include sweating, nausea, chest pain, racing heartbeat, shortness of breath, dizziness, feeling faint, and a sense of impending doom. Most of these can also be caused by a heart attack. So unless you’ve had panic attacks before and are certain that’s what you’re experiencing, you should go to the emergency room if you have symptoms possibly related to a heart attack.
Once a heart attack and other medical problems have been ruled out, your doctor may refer you to a mental health professional for a diagnosis. Many people have one panic attack and never experience another, while others have repeated attacks that grow in frequency and intensity. If you’ve had multiple attacks, you may have a chronic condition called panic disorder, which, if untreated, can lead to phobias.
The underlying cause of panic attacks varies from person to person. Some experts believe the condition is largely psychological. Other factors that may play a role include heredity, significant stress in your life, and the side effects of some drugs (prescription or illegal ones) or dietary supplements. Women, especially after age 50, are more prone to attacks. In addition, some research has found an association between panic attacks and certain diseases, such as irritable bowel syndrome and mitral valve prolapse (a heart valve abnormality).
Because the causes and triggers vary, so do the treatments. Cognitive behavioral therapy helps many people. For others, antidepressants or tranquilizers, sometimes combined with psychotherapy, can be effective at reducing symptoms.

Q: I bought some ground beef that was red on the outside but gray inside. What causes this, and is the meat safe?

A: It should be fine. Meat contains a pigment called myoglobin that turns bright red when exposed to oxygen. Grocery stores typically cover ground beef with a plastic wrap that allows some oxygen to penetrate, so that the surface of the meat turns this appealing red color, which consumers have come to associate with freshness. When ground beef is not exposed to oxygen (as in the inside of the packaged meat), the myoglobin turns grayish-brown after a few days. It may look less appetizing but is safe.
If the ground meat is gray or brown throughout, however, that could indicate that it’s beginning to spoil. If you just bought it, you may want to return it. "Spoilage bacteria," though generally harmless, can make meat smell and cause other signs of deterioration. If you still want to eat it, it’s important to cook it thoroughly.
Of more concern, ground beef is susceptible to contamination from Salmonella, E. coli, and other bacteria that do not affect the color or smell of meat but can make you sick—so it’s essential that you handle and cook all ground beef properly. Use or freeze it within a day or two of purchase, and cook it to 160°F. (71°C.); always use a meat thermometer to check. Color is an unreliable indicator of doneness, as the meat can turn brown before it reaches a temperature that kills all bacteria; conversely, some ground beef may remain pink after it’s cooked to a safe temperature.
By the way, meat can also turn gray in the freezer. It’s perfectly fine and safe to eat.

Q: I’ve heard that you can’t absorb more than 500 milligrams of calcium at a time. So if I get 500 milligrams in a meal, will I get no benefit from taking a calcium supplement around the same time?

A: You’ll still absorb some of it. The more calcium you take in, the more you’ll absorb—though there’s a diminishing return. Keep in mind, your body absorbs only a small fraction of the calcium you consume, whether from food or supplements. And the more you get at one sitting, the smaller the proportion of it you absorb.
If you double your intake from 500 to 1,000 milligrams, for example, you don’t double the amount you absorb, though you do get more in total. With 500 milligrams of calcium, you’ll absorb about 30%, or 150 milligrams. But with 1,000 milligrams, you may absorb only 20%, or 200 milligrams. It’s okay that these percentages are small—scientists take absorption rates into consideration when determining recommended intake levels for nutrients.
It’s still good advice to spread your calcium intake throughout the day, so you don’t exceed 500 milligrams at a time. But ultimately, it’s more important to make sure you reach your daily goal (1,000 to 1,200 milligrams), however you choose to get it, without worrying too much about the size or timing of the doses.

Q: Is it wise to ice a burn? If not, what should I do?

A: Ice might further damage tissue, according to the latest evidence. Cold running water, which also cleanses the area, is the best option. Cold compresses may help, too.
One burn myth is that applying butter or mayonnaise is helpful. Oil, including greasy burn ointments, may retard healing and promote infection. Over-the-counter burn ointments are ineffective and may make matters worse, since they trap heat. Some people find pure aloe helpful, but aloe-containing burn ointments usually don’t have much aloe in them and may be oily. It’s okay to use a first-aid spray containing benzocaine for a very painful burn.
Home treatment is fine for first degree burns (which affect the skin’s outer layer and produce small blisters, if any) and superficial second degree burns (which go deeper and may require medical advice, especially if large). Third degree burns, which may be painless at first because nerves have been destroyed, need prompt medical attention

Q: How do the health benefits of raisins compare to grapes?

A: Ounce for ounce, raisins have nearly three times the antioxidant power of red and green grapes, as measured by one standard test. In fact, they are one of the richest sources of antioxidants of all foods.
That’s not surprising, since when fruits are dried, their compounds are greatly concentrated. (It takes more than six ounces of grapes to make one ounce of raisins.) Most of the vitamin C in grapes, as well as heat-sensitive phytochemicals, are destroyed in the drying process, but obviously plenty survive, since raisins test so high in antioxidant activity.
Raisins are also a good source of potassium, fiber, and some minerals. But remember, the drying process also concentrates the sugars and thus the calories, so watch how many you eat. A half cup of grapes has about 50 calories, while a half cup of raisins has about 220 calories. An ounce of raisins (about 60), with 85 calories, is a good snack.

Q: How often do I need full-mouth X-rays from my dentist? I want to minimize my exposure to X-rays.

A: Every five years or so, but it depends on your oral health and history, your age, and whether you have symptoms or signs of dental problems. You will also need less extensive "bitewing" X-rays every 12 to 24 months. If your oral health is good, bitewings every 24 months or so will be enough. But if you have many fillings, crowns, and bridges, you’ll need more frequent bitewings.
There are three types of dental X-rays. Bitewing X-rays are used primarily for the molars; they show the exposed teeth and only part of the roots. Periapical X-rays show the whole tooth, from crown to root tip, and some of the bone surrounding the roots. "Full-mouth" X-rays include these two kinds. In addition, panoramic X-rays, which provide a wide view of the upper and lower jaw, are used if you have jaw problems, cysts, or impacted teeth, or if you’re going to have a tooth extraction.
The radiation exposure from today’s dental X-rays is very small, but there’s no point in getting X-rays you don’t need. In addition, you should wear a lead apron during the procedure. Pregnant women should postpone X-rays, if possible.

Q: Who should take antibiotics before going to the dentist? I’ve heard different recommendations.

A: Far fewer people than were advised to in the past, according to new guidelines from the American Heart Association (AHA). The idea of taking antibiotics before dental procedures is to prevent bacterial endocarditis, a life-threatening heart infection.
It has long been assumed that people with certain heart conditions—notably mitral valve prolapse (a common structural heart valve abnormality)—were at increased risk of endocarditis after dental procedures because bacteria in the mouth can enter the bloodstream if there is bleeding from the gums. But there’s no scientific evidence to support this. Very few people develop endocarditis after dental work. And antibiotics would prevent only a tiny fraction of cases.
According to the AHA, the overall risks from taking antibiotics before dental procedures as a preventive (including allergic reactions and development of antibiotic resistance) outweigh the very small benefits.
However, the AHA still advises that people at highest risk of having serious complication from endocarditis take antibiotics beforehand, including those with an artificial heart valve, valve problems after a heart transplant, previous endocarditis, or specific congenital heart conditions. The American Dental Association as well as the American Academy of Orthopaedic Surgeons further recommend antibiotics for some other people, notably those who have had a total joint replacement in the last two years.

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