Dear Dr. Blonz: What is the word on melatonin, a dietary supplement that is supposed to help with sleeping and sleep/wake patterns? Is it a reasonable supplement as a sleep aid? -- O.S., New York, New York

DEAR O.S.: Melatonin is a hormone produced by the pea-sized pineal gland that is located in the center of the brain. It is thought to be a key player in the control of the body's sleep/wake rhythms. The release of melatonin is stimulated by darkness and inhibited by light. The rationale behind taking melatonin supplements for a sleep disorder, such as jet lag, is that it can cajole the body into a more rapid shift to the light/dark cycle of a new time zone. There is some research to support this, but it is inconsistent at best. As a sleep aid, a meta-analysis in the Feb. 18, 2006, issue of the British Medical Journal reported that melatonin does not seem to be very effective for sleep disorders.

For most, there is little danger in trying melatonin, as most studies note an absence of adverse effects -- especially when small dosages (3 milligrams per day) and short-term use is involved. Keep in mind that you are taking a hormone normally produced by the body, so unless specifically instructed by your physician, this is not something you want to be taking on a regular basis.

Other sleep aids that can work include a warm glass of milk (flavored or not) before bedtime and/or a warm bath. Tryptophan is an amino acid that serves as the precursor to a neurotransmitter (a key brain chemical) called serotonin, which encourages relaxation. A metabolite of tryptophan, called 5-HTP, is also available, but again, I would not recommend using this product on a regular basis. Valerian is another herb that is also used to treat insomnia, but the evidence here is inconsistent at best. There is a good discussion of insomnia at the National Institutes of Health at tinyurl.com/7l99b4p.

I want to emphasize that the idea of a sleep aid is to get your sleep/wake rhythm back on track, not to have a pill become an essential part of your nighttime regimen. Be up-front with your physician to alert her or him to your sleep issues and avoid potential interactions between your sleep aid and any medications or health conditions.

Other approaches to consider: A good diet and regular exercise habits help with sleep. They not only help to decrease stress, which is a potent sleep robber, but exercise can help tweak the body toward a regular activity/regeneration cycle. There are a number of relaxation techniques and tapes that may be of help.

Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.

DEAR DR. BLONZ: I have started using a hemp milk product with my cereal, and the carton states that it is rich in omega-3 fats -- even more so than fish. I also eat fish, but was wondering if this was true, and if hemp or flax oil can be an effective source of omega-3s. -- F.S., Eureka, California

DEAR F.S.: First, some background on fats. The human body requires both omega-6 and omega-3 fats (or fatty acids), but cannot make them on its own, so they are considered "essential fatty acids" that need to be in our diets. Omega-6 fats are the main fatty acid in vegetable oils, including soy, sunflower and corn oil. One type of omega-3 is found in some vegetables, and a different type is found in seafood. As a general rule, there tends to be an excess of omega-6 fatty acids, and an inadequate amount of omega-3s, in the typical American diet.

Fats can be thought of as long chains of carbon atoms. Omega-3 is a term that refers to the location of the first double bond along the carbon chain: in this case, the third carbon. Omega-6 fats have their first double bond on the sixth carbon.

The location of that first double bond is critical in determining what the body does with a fatty acid, and this is particularly important with the omega-3 fats. The two important omega-3 fats are EPA and DHA, which are 20 and 22 carbons long, respectively. These are the omega-3s associated with blood-pressure benefits, anti-inflammatory effects and a reduced risk of heart disease. (There is a list of fish oil benefits at tinyurl.com/3d8fe9l.)

The omega-3 fat found in your hemp milk -- and in other plant sources such as flaxseed, canola, soy and walnuts -- is only 18 carbons long. It is still an omega-3, but the body has to put it through an extensive "lengthening" process to make it into EPA and DHA. This, it turns out, is an inefficient process. Most of the omega-3s of plant origin get burned for energy, with only a small fraction getting converted into the longer-chain varieties.

The bottom line is that if you want the most effective source of EPA and DHA omega-3 fats, fish is the way to go.

DEAR DR. BLONZ: I heard about some great benefits of drinking lemonade made from real lemons, especially if it helps you consume the juice from at least two lemons daily. My question is, could that result in a loss of calcium, or have any other harmful effects? -- M., via email

DEAR M.: Regarding calcium loss from the body, there is no basis for concern about adding lemon juice, especially the amount provided by two lemons, to your daily diet. About the only side issue might be for the teeth if the lemon juice (or any acidic food) were allowed to stay in contact with the teeth for an extended period. But once swallowed, it's all good.

Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.

DEAR DR. BLONZ: Is there any problem with eating fish, especially salmon, if you have gout? If so, does the problem also apply to fish-oil supplements? I also read that high doses of vitamin C are not recommended for gout patients. Can you shed any light on this? -- L.L., Seattle

DEAR L.L.: Gout is a form of arthritis (inflammation of the joints) that is brought about when there is an excess of uric acid in the blood, which gives rise to deposits of sharp crystals in and around joints. Usually, the first joint affected is the most remote one from the heart -- the big toe -- but gout can affect other joints, as well.

Uric acid is a normal metabolic intermediate that gets produced during the breakdown of certain compounds. Normal kidney function will eliminate uric acid. Gout can develop when the body produces too much, or when the kidneys, for some reason, are not able to do their job. Why this happens is not known, but it is thought there may be a genetic predisposition.

There are prescription medications to help with gout, but an important step is to cut down on foods known to give rise to uric acid during their metabolic breakdown. Purines are substances that turn into uric acid, so those at risk for gout are typically put on a low-purine diet. Some fish and shellfish are high in purine, including sardines, herring, anchovies, cod, trout, haddock, mussels and scallops. Salmon is considered moderate, not high, in purine. Fish oil does not contain purine.

To find out more, consult articles on gout at the Arthritis Foundation (tinyurl.com/nmzytqf) and the National Institutes of Health (tinyurl.com/3ulmzb).

DEAR DR. BLONZ: I recently took a loaf of bread out of the freezer, and it had mold on it. Of course I did not eat it, but was wondering how this could be possible. -- M.M., San Dimas, California

DEAR M.M.: Mold spores tend to be all over the place, and bread is not a sterile food. If your bread had already been opened when you froze it, it is likely a few mold spores were present. There could have also been some mold in the packaging that was used. You don't mention how long the bread was in the freezer, how it was defrosted or how much mold you found. There could have been a small amount of growth during the freezing process. Other factors could be a power outage during the loaf's life in the freezer, or if the loaf was near the freezer door and it was opened often.

Moisture in bread tends to move from the interior to the surface during the freezing process. This helps explain ice crystals that form in the package. During the defrosting process, any ice crystals present will create a high-moisture environment in the package as it returns to room temperature, which is an ideal situation for the mold to spring back to life.

It is difficult to say for sure what happened, but the key is whether this is an isolated incident or a regular occurrence with breads and other foods in your freezer. If it's the latter, you have some detective work to do.

Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.