Dear Doctor: I've been taking niacin for years to lower my cholesterol. Do you think it really helps?

Dear Reader: First, let's look at niacin and its role in the body. Niacin is a B vitamin needed to create compounds crucial to cellular function. A shortage of niacin, or vitamin B3, can lead to diarrhea, nausea, vomiting, rash and, when severe, neurologic conditions that manifest as confusion and dementia. Fortunately, because of our varied and plentiful diet, not to mention food supplementation, niacin deficiency is rare in this country.

Some research does support niacin's ability to improve cholesterol levels. In 1955, in one of the earliest studies of niacin, researchers found that doses of 1,000 to 3,000 milligrams significantly lowered total cholesterol levels in men. Niacin has also been found to lower levels of LDL, the so-called "bad" cholesterol, while raising levels of HDL, the so-called "good" cholesterol.

Niacin has an impact in other ways as well. A 2007 study of 30 patients who took 1,000 milligrams daily showed a reduction in the thickness of their carotid arteries' interior lining and lower levels of CRP (C-reactive protein, a marker of inflammation) when compared to a placebo. Further, a 2009 study of a niacin-plus-statin regimen showed that it led to a reduction in a marker for atherosclerosis in the heart.

Such research suggests that niacin could decrease the risk of heart attacks and strokes. The science, however, is less than conclusive.

A 1986 study followed 1,189 men who had a history of heart attack and compared those who took niacin at 3,000 milligrams per day to those who got a placebo. After five years, the niacin group reported fewer heart attacks, but no difference in the death rate. After 15 years, however, the niacin group reported an 11 percent decrease in mortality rates, mostly from a decrease in heart disease.

Studies of niacin in addition to a statin have not shown benefit against either death rates or heart attacks. A 2011 study in the New England Journal of Medicine assessed the impact of 1,500 milligrams of niacin in addition to the drug simvastatin in those with cardiovascular disease. After three years, the authors found no impact on mortality. A 2014 study in the New England Journal of Medicine echoed these findings, with no benefit after 3.9 years of statin-plus-niacin treatment.

It may be that niacin, when taken with a statin, provides no additional bang for the buck. The significant decrease in heart attacks and strokes seen with statin therapy may overwhelm any potential benefit of niacin. Further, as the 1986 study showed, the benefit of niacin may take up to 15 years to show benefit; the trials of statin-plus-niacin were only for three to four years.

Overall, niacin does seem to have beneficial effects on cholesterol and on reducing atherosclerosis, or hardening of the arteries. However, it's not as powerful as a statin in decreasing rates of heart attacks, and the benefit might not become evident for years.

If you cannot tolerate a statin, niacin may be a good option. But discuss it with your doctor.

(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: We brought our first baby home from the hospital, and it seems as though all he does is sleep. Is this normal? How much sleep should a newborn be getting?

Dear Reader: First, let us reassure you -- as long as your son is feeding, urinating and eliminating regularly (about eight diapers per day) and is gaining weight, all is well. Newborns sleep a lot -- anywhere from 14 to 18 hours in a 24-hour period. Some super-sleepy babies may clock as much as 20 hours per day. Even experienced parents who bring a newborn home can be surprised all over again by how much time their newest addition spends in sleep.

In the beginning, your newborn's sleep patterns can be unpredictable. Day and night are meaningless concepts and can easily become interchanged. Whether your son sleeps in short stretches of 30 to 45 minutes each, or drops off for three or four hours at a time, it's all perfectly normal.

Thanks to his tiny stomach, hunger will often push your sleepy infant to wakefulness, probably every three hours. Newborns feed anywhere from eight to 12 times in a 24-hour period. However, it's not uncommon, particularly in the early weeks, to have to wake your baby for a feeding. We recommend that you don't let your newborn go for more than five hours between feedings.

Likewise, don't be surprised if he drifts off to sleep in the middle of a meal. Sometimes this is just for a 10- or 30-minute nap and he'll be ready to eat again. Other times he's down for the count and will go for another few hours before hunger awakens him.

If your son is consistently sleeping through his feeding times, you'll have to wake him up to eat. For the best results, it helps to recognize his sleep cycles. Just as for an adult, waking from a deep sleep is both difficult and unpleasant. Interrupting sleep during a lighter cycle is less stressful for all involved.

When a newborn falls asleep, he enters what is known as "active" sleep, a cycle similar to REM sleep in adults, the stage in which we dream. That is followed by a "quiet sleep," a cycle in which deep sleep takes place. When quiet sleep ends, typically after an hour or so, the baby either wakes up or starts a new cycle of active sleep.

For the best results in waking your sleepy boy, watch for his active cycle. It's a somewhat restless sleep with the same physical motion and rapid eye movement seen in adult REM sleep. When you see the signs of active sleep, you can begin to wake him.

If he's swaddled, loosening the blanket may rouse him. Use your voice and your touch to draw him out, easing him into the conscious world. Even if he's still sleepy, he can begin to feed. Meanwhile, know that within three months, the quiet life with a sleepy newborn will have become a faint memory.

(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'm 75, healthy, and want to stay that way -- despite a bad family history regarding hearts and arteries. I have taken 10 milligrams of Lipitor daily for several years, but am wondering if I should try coconut oil to lower my cholesterol?

Dear Reader: Coconut oil is very high in saturated fat, with 12 grams per tablespoon. Compare that to olive oil, which has 1.9 grams of saturated fat per tablespoon. Both have 14 grams of total fat, but almost all of olive oil's is monounsaturated, widely considered to be better for the heart and cardiovascular system. Saturated fats in meats and dairy products, on the other hand, have been shown to increase LDL cholesterol, the so-called "bad" cholesterol linked to coronary artery disease.

For someone with a family history of vascular disease, we really have no good data on coconut oil's ability to reduce the risk of heart disease and strokes. We do have observational data from societies that have lower heart disease rates and include coconuts as a significant percentage of their diet. But they're consuming the coconut, not just the oil of the coconut.

One factor to consider: The meat of the coconut has a considerable amount of fiber. This fiber is not found in the oil, and it may be the fiber that confers the greatest benefit from coconut consumption. Also, the diet and lifestyle of societies that consume large amounts of coconut cannot be translated well to our Western diets and lifestyle, meaning they probably are healthier in many respects.

One aspect of coconut oil that we can assess is how it might affect cholesterol levels. As I noted earlier, coconut oil is high in saturated fat. But the majority of the saturated fat is in the form of lauric acid; the majority of the saturated fat in animal fat is palmitic acid. Lauric acid is absorbed differently than palmitic acid, which could suggest that coconut oil doesn't cause the same degree of LDL elevation as animal fat.

But that would appear to be wishful thinking.

A study published in the journal Nutrition Reviews in 2016 analyzed multiple studies and found no difference in the LDL cholesterol level between people who used coconut oil and people who used butter. It does appear, however, that consumption of coconut oil was linked to lower triglyceride levels as compared to beef fat. That said, the cholesterol profiles found among consumers of coconut oil are much worse than those found among people who consume olive oil, canola oil, or even corn, safflower and palm oil.

I believe that you should look at coconut oil as a saturated fat. The current recommendation is that these fats should make up only 10 percent of your diet. You could use coconut oil as a replacement to the fat from meat or dairy.

However, if you have a family history of heart disease, I would use olive and canola oils in recipes and when cooking; these oils have shown beneficial effects in regards to cholesterol.

In addition, if you have risk factors for heart disease, there is a significant benefit in staying on the statin you are taking. I would not stop that in lieu of adding coconut oil to your diet.

(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.)