On Nutrition

DEAR DR. BLONZ: Along with the tuna itself, some canned tuna contains "vegetable broth with hydrolyzed soy protein and hydrolyzed casein." Are these ingredients unhealthy? Does a can of tuna that lists these ingredients contain MSG, which should be avoided? -- S.I., New York City

DEAR S.I.: Proteins are made up of amino acid building blocks arranged in long chains. In the last stage of being produced, these chains get twisted into three-dimensional shapes to fit their functions. Aside from the protein in tuna, products such as the one you describe also contain soy protein (from soybeans) and casein (the primary protein in milk).

A protein described as "hydrolyzed" indicates it has been broken apart into fragments of one or more amino acids. Outside the body, this gets done using enzymes or chemicals. In addition to being chewed, swallowed and treated in the stomach, proteins undergo a similar process with our digestive enzymes to break them into amino acids to facilitate their absorption. Water molecules are used in this breakdown, half on each side of the formerly linked amino acids.

Hydrolyzed proteins are used as ingredients to enhance flavors; nothing weird here. The vegetable broth is also there to enhance flavor. These ingredients are not unhealthful: They represent a blend of amino acids used to achieve a consistent flavor that manufacturers often seek. Such additives, however, could represent an unnecessary risk for the small number of people who react to monosodium glutamate, or MSG.

There has been a lot of controversy regarding MSG -- some of which may be undeserved. The nonessential amino acid glutamate is most prevalent in intact dietary proteins, where it's part of a chain in a three-dimensional structure. On its own, however, glutamate is a key molecule in cellular metabolism. As the additive MSG -- glutamate with a sodium molecule attached -- it can affect flavors. Up to 2% of individuals may have short-term reactions to MSG. Symptoms are typically mild and don't require treatment -- but there can be exceptions. Blind testing, in which your reactions to foods are assessed without you knowing whether MSG is present, can help determine your risk. For individuals found to be sensitive, the only way to prevent a reaction is to avoid foods containing MSG.

Despite concerns raised by early reports and viral proclamations, decades of research have failed to affirm that MSG ingestion must be a concern for all. As an FYI, the May 2017 issue of Food Science & Nutrition reported that the intake of glutamate from the use of MSG as a food additive is much lower than the estimated intake from glutamate naturally present in foods. (Read more on the MSG controversy at b.link/cqrp4m.)

While we are on the topic, food scientists are attempting to find ways to reduce the level of sodium in processed foods. (This is one of the many reasons I recommend focusing on whole foods.) Some are experimenting with the use of the flavor-enhancing potential of MSG. Referred to as a "salt flip," formulators can reduce sodium by substituting MSG to enhance flavor. A study in the September 2020 issue of the Journal of Food Science reported that over two-thirds of the test panel preferred the lower-sodium recipes that contained MSG. The story continues to unfold.

Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 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 it reasonable to take melatonin daily as a sleep aid? -- B.S., Westmont, Illinois

DEAR B.S.: Melatonin is a hormone that plays a role in our sleep-wake cycle; it is produced by the pea-sized pineal gland located in the center of our brain. The release of melatonin is stimulated by darkness and inhibited by light.

The rationale behind taking melatonin as a sleep-aid supplement -- say, in instances of jet lag -- is that it might help shift your sleep-wake cycle to the new time zone. Some research supports this use, but most studies find that melatonin does not seem to be very effective for sleep disorders in general.

Most studies note an absence of adverse effects -- especially when small dosages (3 milligrams per day) and short-term use are involved. However, keep in mind that melatonin is a hormone usually produced by the body, so unless specifically instructed by your physician, it is not something you want to be taking regularly. It is also a substance that can interact with other medications or supplements. If you do take melatonin, be sure to note it on your medical record for your pharmacist and other health professionals to consider. Find out more about melatonin and its uses at b.link/shvcqu.

DEAR DR. BLONZ: What are your thoughts about all the dietary supplements made from dehydrated fruits and greens? These are supposed to be nutritionally identical to the real foods, minus the water and air (so they can fit in the capsules). A five-capsule serving of the product I am considering is said to provide the same nutrients as five servings of fruits and vegetables. Are these a reasonable equivalent to eating the produce itself? -- F.F., Albany, California

DEAR F.F.: Such supplements may have started as foods, but more than water and air get left behind in the manufacturing process. I don't know the specific product you are referring to, but some generic math will show how it would be physically impossible to provide five servings of fruits and vegetables in five capsules -- unless, of course, they were massive pills, too large to swallow.

Servings are specific amounts. According to the USDA, one serving of vegetables is 1 cup of raw, leafy vegetables; 1/2 cup of cooked or chopped raw vegetables; or 3/4 cup of vegetable juice. One serving of fruits is a whole fruit such as a medium apple, banana or orange; a grapefruit half; 1/2 cup of berries, melon or chopped raw fruit; 1/2 cup of cooked or canned fruit; 1/4 cup of dried fruit; or 3/4 cup of fruit juice. Using a modest estimate of 2 grams of dietary fiber in a single serving of a typical fruit or vegetable, we would have 10 grams of fiber in 5 servings. Check the Supplement Facts label on the product and see what is present.

Fiber is just one of many components that should always be considered essential in the fruits and vegetables we eat. Dietary supplements are not meant to replace food.

Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 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: When taking pills -- vitamins, supplements, prescriptions, whatever -- is it important to swallow one pill at a time? Or is it OK to do as I do and take three, four or five in one gulp? As you might imagine, my wife and I have (cordially!) debated this point, and hope you can settle our differences. Don't worry; we very much love each other, so there's no chance of serious domestic strife. -- F.S., via email

DEAR F.S.: It makes no significant difference to our bodies if pills and supplements arrive in the stomach after one swallow, or multiple. The issue is whether your preference for the multi-pill method overtakes your ability to safely swallow the entire bunch at one time.

An overload could present a danger of choking and pill aspiration, which increases with each additional pill. The size, shape and coating of each pill can also affect the risk. The tone of your message suggests some experience at this, but all it takes is an unexpected shock, noise, bump or other distraction at a vulnerable time, and something can go down that "wrong pipe." Another issue is that swallowing difficulties become more prevalent as we age; check the National Foundation of Swallowing Disorders (b.link/buhqds) for more information.

Sorry for the mini-lecture, but multiple-pill swallows represent an avoidable risk. Here's hoping the debate with your partner goes down without a hitch.

DEAR DR. BLONZ: Both copper and zinc are in the mineral supplement I am taking, but I have read it is not a good idea to combine them. What is the problem here? -- S.F., San Francisco

DEAR S.F.: We understand the amount of nutrients needed to prevent a deficiency. Still, we have only begun to tackle the complexities of how they interact -- particularly if disease conditions are in play.

Zinc plays a role in many enzymes, including those involved in detoxification, sex hormone production and wound healing, and it is also involved in our senses of taste and smell. Copper helps form red blood cells, is essential for normal hair and skin, and is needed for normal respiration and the production of certain antioxidant enzymes.

Both are essential, but an excess of zinc can deplete the level of copper in the body. Likewise, if the copper intake is excessive, zinc can suffer. While uncommon, the odds of an imbalance can increase with environmental conditions -- such as toxic levels in drinking water, elevated levels in certain foods, or cooking acidic foods in poorly maintained copper pans -- or with certain health conditions. Taking supplements that overload one nutrient over the other can also be an issue.

The Daily Value for zinc is 15 milligrams, and the tolerable upper limit is 40 milligrams per day. For copper, the Daily Value is 2 milligrams, and the tolerable upper limit is 10 milligrams per day. (These figures are for adults 19 years of age or older.)

While there is no problem with the recommended amounts, even if taken together, take care not to overdo it with either one unless there is a medical reason to do so. Read more from the National Institutes of Health on zinc at b.link/pnnsvv and copper at b.link/66d6km.

Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 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.