Dear Doctor: I'm old enough to remember when eggs were good, then bad, and then so bad they were probably going to give you a heart attack. Now I'm hearing we've come full circle and eggs are good for you again. What gives?

Dear Reader: We're right there with you on the confusing -- and seemingly endless -- back-and-forth about whether eggs are friend or foe. Now, the continuing line of inquiry that ushered the egg white omelet into our lives has produced new research that comes out in favor of the beleaguered egg. According to findings from a study published in the journal Heart, eating an egg each day may reduce the risk of stroke by as much as 25 percent. This is a departure from previous studies, which had either identified eggs as problematic for cardiovascular health or at best were inconclusive on the subject.

At the root of the egg's bad rep is one particular stat in its nutritional profile. At just about 70 calories each, eggs provide varying amounts of vitamins A, B2, B12 and folate, trace minerals like selenium, iodine, iron and zinc, and about 6 grams of protein. They also contain a hefty dose of cholesterol -- about 210 milligrams each -- which is what landed them on the nutritional blacklist. But as of 2016, the federal government's Dietary Guidelines for Americans dropped its recommendation to limit dietary cholesterol to 300 mg per day, which in turn eased restrictions on eggs.

Meanwhile, because cardiovascular disease and stroke have become a leading cause of death in China, as in the rest of the developed world, researchers there looked into the role of eggs in the diet. They mined data gathered from more than 500,000 participants in an ongoing health initiative known as the China Kadoorie Biobank study, which uses questionnaires, a range of physical measurements, and regular blood samples to track health outcomes. They focused on data from individuals who ranged in age from 30 to 79, came from a wide geographic area, and were free of cancer, cardiovascular disease and diabetes at the time they joined the study.

In sorting the data for the effects of eggs in the diet, researchers discovered that people who ate an egg each day had a lower incidence of cardiovascular disease overall than those who ate no eggs. They had a 25 percent lower incidence of hemorrhagic stroke, which is the rupture of a blood vessel in the brain, and a 12 percent reduction in risk of ischemic heart disease, in which narrowing of the arteries results in less blood and oxygen reaching the heart.

As the study's authors themselves point out, it's important to remember that this is an observational study. While results can be extrapolated, the specific conditions that contributed to the outcomes are not known. What's encouraging for egg lovers is that the results appear to bolster the new(ish) understanding that cholesterol levels in food don't automatically translate to a corresponding rise in blood levels of cholesterol. So while the conversation about eggs is likely to continue for some time, for now, eggs in moderation for people without heart disease or the risk for heart disease have gotten a green light.

(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: Do "eye vitamins" have any benefit at all? I know a lot of seniors who believe in them, but I'm skeptical.

Dear Reader: Skepticism should be a marker for overall health, especially with the flood of vitamins sold in vitamin shops, grocery stores and pharmacies. Vitamin supplements have been touted for nearly every condition with scant evidence of their efficacy when compared with a healthy diet.

Lutein and zeaxanthin generally top the list of "eye vitamins." That's because these dietary carotenoids -- related to beta carotene and vitamin A -- help form retinal macular pigment. This pigment absorbs damaging light rays and thus protects the macula, the part of the retina responsible for detailed vision. Additionally, these carotenoids are antioxidants, protecting the eye from cellular damage.

Now let's examine the evidence. Diets high in lutein and zeaxanthin have been associated with a lower risk of the late changes of macular degeneration. And, in a review of eight studies, higher blood levels of lutein and zeaxanthin were linked to a decreased cataract risk. Leafy green vegetables such as lettuce, spinach, kale and parsley are high in these carotenoids, as are eggs, so a diet containing these foods may help protect your vision.

But taking a vitamin? In people who already have macular degeneration, antioxidants such as vitamin C, vitamin E, lutein and zeaxanthin do seem to slow the progression of macular degeneration. In fact, these antioxidants -- when taken with zinc -- are linked to a 28 percent reduction in late macular degeneration. People who substituted beta carotene for lutein and zeaxanthin reported similar benefits. Note, however, that beta carotene has been associated with increased lung cancer rates in people who smoke.

That's not to say that antioxidants lower the chances of developing the disease in the first place. A 2017 review of five studies assessed the impact on 55,614 people without macular degeneration who took antioxidants from four to 10 years. The authors found that neither vitamin E, vitamin C nor beta carotene decreased the rate of macular degeneration compared with a placebo. In fact, vitamin E was associated with a slight increase in the rate of late macular degeneration.

As for multivitamins, one of the studies assessed the potential effects of the multivitamin Centrum Silver and found a 22 percent relative increased rate of macular degeneration compared with a placebo.

As for non-antioxidant vitamins, a 2009 study did show a decreased rate of AMD with higher doses of B vitamins (specifically B12, B6 and folic acid). The study included 5,442 female health care professionals who had either risk factors for coronary artery disease or actual cardiovascular disease and who took B vitamins. After an average follow-up time of 7.3 years, women who took the B vitamins had a 34 percent decreased risk of macular degeneration. Increased dietary intake of B12, B2 and B3 also has been associated with a decreased rate of cataracts.

My recommendation is to get most of these so-called "eye vitamins" from your diet. If you have risk factors for heart disease, you may find benefit with B vitamins, or if you have macular degeneration, you may benefit from antioxidant vitamins. But that's as far as the science on "eye vitamins" goes.

(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.)

Hello, dear readers, and happy summer! We hope you're getting a chance to enjoy the longer days and warmer weather. Here at Ask the Doctors headquarters, our mailboxes continue to overflow. Let's dive in.

-- Regarding the column we wrote in response to a reader who has frequent bouts of strep throat, we heard from Martha, a reader whose family had an unexpected experience with the bacterium:

"One of our children got repeated and frequent strep infections," she wrote. "Finally, the pediatrician suggested we test the whole family, and we found we had a carrier -- our then-toddler, who had no symptoms at all." Once the toddler was treated with a course of antibiotics, the incidents of strep within the family stopped.

The toddler is an example of what is known as an asymptomatic carrier. That is, although the individual is a host for a bacterium or a virus, they are not adversely affected. However, as Martha and her family learned, people who come into contact with the carrier can become infected and fall ill. Strep, typhus, C-difficile, norovirus, Epstein-Barr and even HIV are just a few examples of infectious agents that have been found in individuals with no outward symptoms.

-- After reading our column about genital herpes, a reader asked for help in dealing with the pain and itching that often accompany an outbreak. Although there is no cure for herpes, there are several antiviral medications that can curtail the length of an outbreak by several days, if taken at the first sign of symptoms. The antivirals acyclovir, famciclovir and valacyclovir are prescription-only. People living with herpes who have frequent outbreaks sometimes opt for suppressive therapy. That is, they take an antiviral every day.

For localized symptoms like pain, over-the-counter pain relievers can be helpful. As for itching, an intriguing study found that ointments and creams containing propolis, a resin-like substance made by honeybees, was more effective than both a placebo ointment and a topical treatment containing the antiviral acyclovir. Dosing depends on a user's age and general health, so if you decide to give this alternative treatment a try, please check with your family doctor for user guidelines.

-- We heard from a reader regarding the claims that coconut oil is useful as an agent to either prevent or treat Alzheimer's disease. One of the theories behind the idea is that the brains of Alzheimer's patients can't break down glucose and that certain properties of coconut oil provide an alternative energy source.

Although the use of coconut oil has indeed shown promise in several small clinical trials, the benefits at this time remain largely anecdotal. The good news is that there is now increasing interest in this area of study, and the larger studies that are needed to corroborate and expand on the existing research are quite likely on the horizon.

In the meantime, for those of you following through with the use of coconut oil, please remember that it is a saturated fat. Depending on your daily diet, its use may require you to make corresponding adjustments.

(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.)