DEAR DR. BLONZ: I was shopping for an upcoming party and considered purchasing grated cheese to save prep time in the kitchen. I have gotten into the habit of reading the labels of any packaged foods that I buy, and this one gave me pause. I know that fresh cheese is usually made from some type of milk along with salt and enzymes, but the package of grated cheese listed natamycin as an ingredient. I have no idea what that is. There was also powdered cellulose listed, which is a bit more familiar, but I am not certain why it is required either. Are these things I need to be concerned about? -- N.Z., via email

DEAR N.Z.: Finding unknown ingredients on your food labels can be troubling, especially if they have imposing-sounding names. It's easy to become concerned that something unwholesome is in the package. Ingredients -- even entirely wholesome ones -- often sound more onerous than they actually are, and in this case, there is little cause for concern.

When cheese is grated, there is a great increase in surface area, and with this increased area comes more space for unwanted molds or yeasts to grab on and make themselves at home. The natural moisture present in cheese can also create a friendly environment. Grated cheeses are usually packaged under a controlled atmosphere to inhibit the growth of such organisms, but that would not prevent them from being introduced and growing after the package is opened.

Natamycin is a naturally occurring preservative compound that helps prevent the growth of undesirable molds or yeasts. It is often used with cheeses because it doesn't work against the friendly bacteria that are essential for flavor development during the ripening process. You can find products that don't contain this preservative, but it is doubtful that it is cause for concern. It, along with the protein in the cheese, will be denatured and destroyed during the digestive process.

The powdered cellulose, a naturally occurring carbohydrate from plants, is there to prevent the grated cheese from clumping together. Cellulose, which is not digested, is the most plentiful carbohydrate substance in nature. It is actually considered to be dietary fiber, but such a small amount is needed for anti-caking purposes that the fiber won't even register on the nutrition label.

Regarding food additives in general, you can limit the problem by sticking to whole or minimally processed foods, but even this is no guarantee. As a group, food additives are a mixed lot, containing a variety of substances that accomplish some rather amazing things. They are all chemicals -- one and all -- but the same can be said for all foods, whether they come fresh from the garden or from a package on the shelf.

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 read with interest your article on the Sensa weight-loss product. Although you did not state a definite "yea" or "nay" on the product, I thought I would share that I've been on Sensa for five months and have lost 36 pounds. I was skeptical at first, but am now a firm believer in the product. If you sprinkle it on all foods (except liquids) and drink at least 64 ounces of water a day, you do lose weight. The weight loss is slow, as it should be. Sensa also has an awesome support community online and a coach to answer any questions about the product. Just my two cents. -- J., via email

DEAR J: Thanks for the two cents. I don't often write twice about a particular product, but yours is a wonderful story and you have my congratulations. But in addition, I wanted to explain the basis for my obvious skepticism, which goes beyond this product and is reflective of the field of weight-loss products in general. Namely, my skepticism is based on the lack of reliable, objective evidence affirming the effectiveness of this product -- and many others.

Not to lessen your ongoing accomplishment in the slightest, but you can find individuals who write about successful experiences with most approaches. I look for support that is evidence-based and objective. The testing of a product or theory is only considered objective when it's conducted by individuals who have no association with the success of the method, and one must be reserved in the claims for any product until such evidence has been gathered. What is needed is a controlled test of each method, with the results then written up, put through a peer-review process and published in scientific literature. Until that happens, all we have are products being promoted by those with a financial interest in sales, and associated theories where we don't really know what might be causing what.

For example, you state that you are drinking at least 64 ounces of water a day. A review article in the December 2009 issue of the journal Eating Behaviors reported that increased consumption of water, by itself, is associated with a decreased caloric intake. Granted, none of the studies summarized in that report found that water consumption was associated with weight loss approaching 2 pounds a week, like yours, so something is obviously going on in your case. But does the Sensa produt involve an actual biochemical mechanism that will work for others?

There is also the "you gotta believe" aspect: There is evidence in the scientific literature that a significant part of any approach to weight management is a personal commitment to it and a belief in its efficacy. One using a method because of personal motivation is more likely to be successful than another who is only using the same method at the insistence of another. Marketing and support services can serve as important adjuncts to success, but nothing replaces personal motivation and belief.

You have my wishes for your continued success. Keep me informed of how things proceed.

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: My boyfriend works at night and then takes melatonin to help him sleep during the day. For a number of weeks, he has been taking 3 milligrams a day. I told him that I wouldn't personally take it every day, but he said that otherwise he wouldn't get sufficient sleep. His job requires him to be alert, so getting enough sleep is crucial. I have looked up melatonin online but keep finding conflicting information. What do you recommend? -- J.K., San Jose, Calif.

DEAR J.K.: I question the use of melatonin on a regular basis for this purpose, especially if your boyfriend's work schedule is consistent. Melatonin should not be thought of as a sedative or a sleeping pill; it is more along the lines of a hormone that can facilitate "re-education" to reset your body to a new sleep schedule. Once the sleep pattern has been established, it has done its job. There are legitimate concerns about the taking of an unneeded hormone as a part of one's daily regimen.

Our bodies respond to daylight and darkness, and the hormone melatonin plays a role in the sleep/wake cycle. It is released by the pineal gland after we shut our eyes and go to sleep, which usually occurs at night in the dark. Seeing as your boyfriend is sleeping during the daylight hours, the room where he sleeps should be completely dark. If he routinely wakes during his "night" to visit the bathroom, that room should, if possible, be dark as well. When he wakes up at the end of his sleep, he should get some exposure to bright light. If there is no sunlight when he wakes for his "day," he might consider buying a full-spectrum light. The idea here is that he should do his best to educate his body that his pattern is the norm. When it is his sleep time he should avoid computer monitors, televisions, e-readers or tablets with bright screens, as this light can inhibit the body's normal melatonin production. (This is good advice for anyone having trouble getting to sleep.)

Your boyfriend should check with his physician to make sure that melatonin, or any other product, will not present a problem with his health profile. Thinking beyond medicinal fixes, eating well and exercising both help with sleep by decreasing stress, which is a potent sleep-robber. Exercise also helps tweak the body toward a regular activity/regeneration cycle, sleep being where regeneration takes place.

Other ideas: There are a number of relaxation techniques and tapes that may be of help. A warm glass of milk before bedtime is a tried-and-true remedy, as is a warm bath. Tryptophan, an amino acid, may also help -- it's the precursor to the neurotransmitter serotonin, which can encourage relaxation.

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.