Dear Doctor: Does zinc help with colds?

Dear Reader: Zinc is an important element needed for a healthy immune system. The link between zinc deficiency and infections was first noted in the Middle East 50 years ago. Some zinc-deficient patients had such severe immune dysfunction that they died by age 25 from infection. That's because cells that are deficient in zinc have a decreased production of interleuken-2, a necessary immune and inflammatory regulator. In the United States, this level of deficiency is rare because zinc is found in so many foods; elsewhere, it's seen among the severely malnourished.

As for its benefits, a United Kingdom study of people 65 and older found no benefit in the severity or the number of days of infection with a common cold among those taking a multivitamin that contained 20 milligrams of zinc versus those who took a placebo.

When it comes to higher doses, the results are more mixed. A review of 13 studies assessed the impact of zinc on the common cold. Daily doses varied from 30 mg up to 207 mg. The majority of the studies had people use lozenges every two hours while awake. The effects of zinc lozenges were compared to the effects of a placebo, and participants took them as long as the cold symptoms lasted. Seven studies found benefit with the use of zinc lozenges, while six did not.

The authors concluded that the greatest factor in regards to zinc efficacy was the dosage. In the studies that used less than 75 mg per day, no benefit was seen. However, seven of the eight studies that used more than 75 mg did show benefit. Of these seven studies, zinc lozenges decreased the duration of a cold from 0.4 days up to 3.6 days.

A separate 2012 review of 17 studies, with a combined total of 2,121 participants, also analyzed the impact of zinc lozenges or tablets compared to placebos. Three of the studies focused on children under 18. Overall, of the 17 studies, only eight measured the duration of symptoms, finding that zinc decreased symptoms on average by 1.65 days. However, no benefit was seen in children, and doses of less than 75 mg per day were linked to a decreased duration of symptoms of only 0.84 days. The research also showed a mild benefit in reducing the severity of symptoms in adults, but not in children.

In both review studies above, participants reported significant nausea and a bad taste in the mouth with the use of zinc. Note that the FDA has warned against the use of nasal preparations with zinc due to an irreversible loss of smell.

In summary, studies suggest a mild benefit for adult colds with the use of high daily doses of zinc. But, at these doses, you may be trading the benefits of decreased cold symptoms with the side effects of nausea. If you can tolerate a daily dose of greater than 75 mg, then zinc may be a good addition when fighting a cold.

(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: My husband thinks that sleeping for more than five hours a night is a waste of time. But I just read that not getting enough sleep can predispose people to illness. Is this correct? I would love to be able to persuade him that sleep is actually good for you.

Dear Reader: Getting enough hours of sleep is crucial to staying healthy. Yet a surprising number of people resist the idea. We will happily tell you what is known about the benefits of sleep and hope that it will be enough to persuade your husband.

People who don't get enough sleep simply don't function as well as those who do. Paying attention at work, staying alert while driving, performing tasks that require decision-making or a judgment call -- all become more difficult when you haven't had enough sleep. Sadly, chronic sleep insufficiency can cause behaviors that lead to injury and death.

Hundreds of studies over the years have shown that a lack of sleep, which is often referred to as "sleep insufficiency," also plays a role in chronic disease. Researchers have concluded that lack of sleep adversely affects the immune system and increases inflammation. Individuals who don't get enough sleep on a regular basis are at increased risk of cardiovascular disease, diabetes, cancer, hypertension and obesity.

How much sleep is enough?

Adults need at least seven hours of sleep per night. For adolescents, that number climbs to nine hours per night. Getting adequate sleep helps regulate the metabolism, keeps emotions on an even keel, aids in reasoning and memory, helps the brain recuperate and plays a role in physical coordination. In fact, sleep is so important to health and well-being that the Centers for Disease Control and Prevention consider the chronic shortage of sleep among Americans to be a public health issue.

Children who don't get enough sleep are more likely to become obese than those who sleep enough. Both children and adults who don't get enough sleep are at increased risk of mental and emotional problems as well. Depression, anxiety, impaired behavior and mood disorders are all associated with lack of sleep.

The latest scientific data to bolster the importance of getting enough sleep comes from a fascinating study published last February. Conducted at the University of Washington Medicine Sleep Center in Seattle, scientists studied 11 sets of identical twins. Although the twins shared identical DNA, their natural sleep patterns differed greatly.

Each of the study participants slept at least seven hours per night. But one twin in each pair slept at least one hour less per night than the other twin. When blood samples collected from each participant were examined, the twin who got less sleep had measurably lower function in the immune system than did the twin who slept more. And, as you noted in your question, this means less sleep can lead to greater susceptibility to illness.

The truth is, we get quite a few questions about sleep, battling insomnia and how to sleep better. We'll address these soon in an upcoming column.

(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 am 60-year-old female who suffers from darkening of my face. A doctor did a biopsy and it was determined that I suffer from melasma, which began as soon as I hit menopause. Dermatologists seem unable to help. What can I do?

Dear Reader: Melasma is the hyperpigmentation of the skin that occurs mostly upon the sun-exposed areas of the face. This manifests as darker patches of skin that can be irregular and, when severe, cause significant cosmetic disfigurement, which can have a significant impact upon one's social life and the ability to enjoy leisure activities.

It has been linked primarily to various alterations in female hormones. In fact, 90 percent of cases occur in women. Potential melasma-inducing changes occur in the third trimester of pregnancy, when estrogen and progesterone levels are higher, and among women who take oral contraceptives. The breast cancer drug tamoxifen, which blocks estrogen receptors, also has been linked to the condition, and -- for melasma of the arms -- so has hormone replacement therapy. Menopause may increase the chance of getting melasma in other areas beside the face.

Because the condition occurs upon sun-exposed areas, the first intervention you can do is to use sunscreen with an SPF of at least 30. Your dermatologist may already have recommended skin-lightening agents such as hydroquinone, azelaic acid, mequinol or kojic acid. The side effects of those substances include redness and irritation of the skin, even peeling. Worst of all, bleaching agents can cause a decrease in pigmentation, so in addition, you may have to deal with patches of non-pigmented skin.

Retinoids (such as tretinoin), which are derivatives of vitamin A, also work well to treat melasma and have been used in combination with bleaching agents. The best efficacy was seen in a study showing that a combination of hydroquinone, tretinoin and a steroid cream led to a 75 percent reduction of pigment in 70 percent of patients.

Superficial skin peels using chemicals -- often glycolic acid or salicylic acid -- have also shown success against melasma. One study compared the results of 20 patients in India who used six glycolic acid peels to the results of 20 patients who used a combination cream of hydroquinone, tretinoin and hydrocortisone. Eighty percent of the peel group reported their improvement as excellent, versus 60 percent of the cream group. However, other studies have found that chemical peels were no different than bleaching creams in regards to efficacy.

Laser therapy has been used for melasma, but it has significant side effects and may lead to both decreased and increased pigmentation. The side effects are greater in those with darker skin. Finally, two studies have found that the topical serum rucinol, which inhibits the formation of melanin, can decrease pigmentation.

In your case, I would first and foremost try to decrease the sun exposure to your face and, if you're taking hormone replacement therapy, I would talk to your doctor about stopping it. Next, consider the use of a cream that combines hydroquinone, tretinoin and a steroid. If that doesn't work, consider chemical peels. If those don't work, then topical rucinol would be an option.

One other course of action is to use makeup with titanium or zinc oxide. Not only do these minerals camouflage the pigmented areas, they also work well as sunscreens.

Some of my patients have dealt with melasma, and I know it can be frustrating, but keep in mind that the dark spots may be more obvious to you than to others.

(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.)