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.)

Dear Doctor: I recently began running again after a six-year hiatus. My only problem is that my heels hurt after I run -- so much so that I limp for a few minutes the next morning until my body adjusts. As the day progresses, I stop noticing the pain. Any suggestions?

Dear Reader: Running is supposed to be good for you, so it can seem perplexing and frustrating when, instead, it causes pain. In your case, I suspect the cause is plantar fasciitis.

The plantar fascia is a band of thick tissue that attaches to your heel bone (the calcaneus) and extends from there all the way to the base of your toes, providing support for the arch of your foot. Because the plantar fascia is prone to inflammation, it's a common cause of foot pain in adults. This inflammation, known as plantar fasciitis, is most common in adults ages 40 to 60 and accounts for nearly 1 million doctor visits each year in the United States.

One-third of the time, as in your case, the symptoms are on both sides. Runners and dancers are more likely to develop plantar fasciitis than people in the general population because of repetitive trauma. In runners, the pain can be related to poor-fitting running shoes; tightness within the calf, Achilles tendon and hamstrings; flat feet; or running on hard surfaces.

The typical symptom, which you described, is pain in the heel that is noted with the first step out of bed. The pain is sharp and may subside with walking, but may reoccur by the end of the day if an affected person is on his or her feet all day.

Your doctor can usually diagnose plantar fasciitis simply by examination, although he or she may recommend X-rays to rule out other causes for heel pain.

As for what you can do, I would recommend stretching. Tight calf muscles and Achilles tendons can cause the heel to lift so that the contact point with the ground when walking and running is at the area of the plantar fascia. Stretching the calf and even the hamstring can help change that contact point. A foam roller can massage and stretch the calf and hamstring, as can a nighttime splint that keeps the calf stretched and the foot flexed upward. Also, just as stretching the back of the leg is helpful, so is strengthening the muscles at the front of the leg. A physical therapist can recommend specific exercises.

Other pain-reducing tips include buying shoes with good arch and heel support, and using heel inserts to cushion the heel while walking or running. NSAIDs such as ibuprofen and naproxen can decrease inflammation and pain, as can icing your heels after a run.

Finally, you should curtail the running until the pain in your heels subsides. Don't resume it until you've improved your biomechanics through stretching and strengthening exercises.

If the pain persists, a doctor may recommend a steroid injection into the heel, but this should be reserved for people who have not been helped by physical therapy and courses of oral anti-inflammatories.

(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.)