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Q.ÌýI've heard that apple cider vinegar can clean out the arteries. Is there any truth to that?

A.ÌýIf you believe the stories written about apple cider vinegar, it is a miracle cure for just about anything that ails you, from curbing the appetite toÌýdetoxifying the body, boosting the immune system, treating arthritis, and improving circulation. That's a tall order for a brew made from fermented apples. But there's no evidence to back up most of these apple cider vinegar claims.

Q.ÌýMy pulse is usually on the fast side. Does a high heart rate mean I have a problem with my heart?

A.ÌýIn otherwise healthy people, I don't usually worry about the heart rate unless it is consistently above 100 beats per minute at rest. Heart rates that are consistently above 100, even when the patient is sitting quietly, can sometimes be caused by an abnormal heart rhythm. A high heart rate can also mean the heart muscle is weakened by a virus or some other problem that forces it to beat more often to pump enough blood to the rest of the body.

Q.ÌýYou wrote about weak, brittle fingernails with longitudinal ridges. I have strong nails with horizontal ridges. What causes this, and what can I do about it?

A.ÌýYou may be referring to Beau's lines, which are grooves that run horizontally across the nail plate. They usually develop when nail plate growth, which begins in the nail matrix (located under the cuticle), is temporarily disrupted. This can occur with direct injury to the nail matrix; an inflammatory condition such as psoriasis; infection around the nail plate; repetitive picking at the nails or cuticles; or even a manicure. Systemic causes include a common side effect of chemotherapy, nutritional deficiencies, illnesses accompanied by high fever, metabolic conditions, and diminished blood flow to the fingers (from Raynaud's phenomenon, for example).

Exercise and stretch daily to keep ankles flexible.

Ankle stiffness can do a number on your mobility. It can make it difficult to remain active or even get out of bed in the morning and walk across the room. "Motion restriction usually occurs more in the upward than downward direction, so it becomes harder to walk uphill, wear flat shoes, or keep feet pointed straight ahead," says Dr. Christopher DiGiovanni, chief of foot and ankle surgery at Harvard-affiliated Massachusetts General Hospital.

A tricky joint

The ankle is a vulnerable structure. It's made of the ends of the lower leg bones (the tibia and fibula), which hold the talus bone of the foot in between them. The joint is stabilized by ligaments and powered by muscles that work in concert to enable ankle and foot motion and accommodate uneven surfaces when you stand or walk.

Do a little detective work before digging into that dessert.

Treating yourself to a small dish of an icy dessert used to be simple: we had a limited number of dessert types and flavors available, like chocolate ice cream or orange sherbet. Today there are so many options at the grocery store you may feel a brain freeze before you even take a bite.

You'll find ice cream, frozen custard, frozen yogurt, sherbet, and gelato. It may be full fat, reduced fat, low fat, nonfat, low carbohydrate, or sugar-free.

Sales of cannabidiol-infused products are expected to top $2 billion by 2021. But is CBD right for you?

Cannabidiol (CBD) is touted as a natural wonder that can help treat symptoms of everything from anxiety to arthritis pain. The plant extract comes from two varieties of cannabis � hemp and marijuana � and is available in creams, tinctures, oils, patches, gummy bears, capsules, and more. You can even add CBD to a latte if you walk into a coffee shop in some cities.

But is CBD safe for older adults? There haven't been a lot of large studies of CBD's safety, but more traditional medicines for pain and anxiety are not free of adverse effects, either. "I think CBD is likely safer than many other treatments people use for pain, insomnia, or anxiety," says Dr. Peter Grinspoon, a primary care physician with Harvard-affiliated Massachusetts General Hospital. Other physicians don't think we know enough about the safety profile of CBD to be sure.

News briefs

Are you eating enough fiber each day? The recommended dietary fiber intake in the United States is 25 grams per day for women (about three half-cup servings of legumes) and 38 grams per day for men. But most people eat only half of that. Now a study commissioned by the World Health Organization, published online Jan. 10, 2019, by The Lancet, offers more evidence about why fiber is an important player in good health. Researchers combed through more than 240 studies and clinical trials and found that people who ate the most fiber-rich foods had the lowest risks for dying or developing chronic disease during the studies, compared with people who ate the least amount of fiber-rich foods. How much did the risks fall? For every 8-gram increase in dietary fiber eaten each day, the total number of deaths and cases of heart disease, diabetes, and colorectal cancer decreased by 5% to 27%. The authors say that eating 25 to 29 grams of fiber per day is adequate, but eating more than 30 grams per day might offer even more protection.

Image: © Elenathewise/Getty Images

News briefs

Many people think the only reason for regular exercise is that it helps you maintain a healthy weight. Not true. A sedentary lifestyle can cancel the potential heart benefits of weight control, according to a study published online Dec. 4, 2018, by the American Journal of Cardiology. Researchers looked at five years' worth of health survey responses and weight calculations from thousands of overweight and normal-weight people ages 40 to 79 who'd never had heart disease. Scientists noted the participants' amount of abdominal fat, waist size, and self-reported amounts of physical activity, then calculated everyone's cardiovascular disease risk. The results: 30% of sedentary people with a normal weight had about the same risk for a heart attack or stroke as people who were overweight. Sedentary adults whose weight was normal also had higher levels of belly fat, shortness of breath upon exertion, and an unhealthy waist circumference compared with normal-weight adults who exercised regularly. However, people with a normal weight who exercised at least 150 minutes per week were 58% less likely to have a heart attack than those in the study who were overweight.

ÌýImage: Halfpoint/iStock

What the latest science says about caffeine's influence on your heart, memory, sex life, and exercise performance.

Americans are jolted with caffeine. On average, about 80% of adults take some form of caffeine every day, according to the FDA, usually from coffee, tea, soda, or energy drinks.

But does all that caffeine have any effect on your health � either good or bad? "While caffeine can give you a temporary mental and physical boost, its impact depends on how much you consume and the source," says Dr. Stephen Juraschek, an internal medicine specialist at Harvard-affiliated Beth Israel Deaconess Medical Center.

You can do an all-around workout in just five minutes if you focus on intensity and target the main muscle groups.

Growing evidence continues to show that high-intensity interval training (HIIT) offers similar � or in some cases even superior � results compared with longer, lower-intensity workouts. With HIIT, you exercise for a short burst at near-maximum effort followed by a brief rest period, and then you continue to repeat the cycle over the next 10 to 15 minutes.

Small workouts, big gains

The main advantage to HIIT is that it takes less time than the traditional workout of 20 to 30 minutes or longer.