DEAR DR. BLONZ: I am hoping you have some information about taking copper and zinc at the same time, as I have read there is an issue with this combination. They are both in the dietary supplement I take, but I will switch to another one if this combination is not a good idea. -- I.R., Berkeley, California

DEAR I.R.: We have good methods to determine the amount of a nutrient needed to prevent a deficiency; this comes mainly from knowing what that nutrient does, and being able to assess when normal functioning is not taking place. Science, however, continues to learn about how nutrients interact during absorption, and how the ratios between nutrients can affect our metabolisms.

Copper and zinc are both essential minerals, but they have a relationship in which their relative amounts are also important. Zinc plays a role in many enzymes, including those involved in detoxification, sex-hormone production and wound healing, and it is also involved in taste and smell. Copper helps in the formation of red blood cells, is essential for normal hair and skin, and is needed for normal respiration and the production of certain antioxidant enzymes.

Excess zinc can actually deplete the level of copper in the body; conversely, if there is too much copper, the level of zinc can suffer. This antagonism only comes into play with imbalance, and that is rarely an issue when foods are the source of these minerals. The take-home message relates to supplements, and that you shouldn’t overdo it unless there is a medical reason to do so.

There is no problem with taking the recommended amounts of zinc and copper at the same time. For adults aged 19 and older, the Daily Value for zinc is 15 milligrams per day; the tolerable upper limit is 40 milligrams. For copper, the daily value is 2 milligrams per day; the tolerable upper limit is 10 milligrams. For those not familiar with the “tolerable upper limit” term, it represents the highest level of intake that is likely to pose no risk of adverse health effects in almost all healthy individuals.

DEAR DR. BLONZ: I am 75 years of age, and my total cholesterol tends to run about 250 milligrams with the HDL portion at 80 milligrams. If I eat nutritious, healthy foods, will I be able to do normal exercise, such as low-impact aerobics, without ill effects? -- A.B., San Diego

DEAR A.B.: The fact that you are 75 and aware of the importance of healthful eating and exercising means that you’ve been doing several things right. Your cholesterol figure, by itself, might not place you in what’s considered a high-risk category for heart disease, especially given the HDL portion.

But there is much more to be considered in the big picture of your health and fitness, including any past health issues and current medications. The most appropriate reply to your query is best left to the health professional entrusted with your overall care.

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: For the three years since leaving graduate school, I have been attempting to start my own business, and my job has become more intense. In college, I visited the gym, worked out and ate well, but now I have no time to exercise, except a bit of walking.

I am most concerned about my diet. I’m constantly eating fast food or convenience food, as there is no time to cook. I usually rush out in the morning with very little to eat, then I literally don’t eat again until I come home eight or nine hours later, unless I am lucky enough to pass a fast-food store. At home, I make phone calls and then eat my dinner at 11 p.m. or later. I am still young, so I am hoping that my body will be forgiving during this phase of my career. My girlfriend is quite concerned, and it is affecting our relationship, so I wanted to ask: How dangerous is what I am doing? -- R.T., St. Louis, Missouri

DEAR R.T.: I understand these concerns, and it is good you are looking for answers. It must be difficult for one who knows better ways to find himself immersed in a lifestyle that has wandered far afield from previously healthful habits.

How dangerous are your current habits, you ask? That’s a difficult question to answer with certainty, because much depends on elements such as your age, weight, genetics and any pre-existing risk factors.

It is not uncommon to find ourselves in an “investment phase” at work, where intense dedication is needed to open doors and even create new ones. But you’ve been at it for three years, and I am hoping there is an end -- or at least a gearshift -- in sight. I apologize for all this lecturing, and I have no idea what you do for a living, but I would imagine -- or should I say, hope -- that the payoff will be sufficient to justify these current travails.

The good news is that there are obvious remedies at your disposal, and “nudges” you can make to your torrid lifestyle. All you need is the wherewithal to make the changes.

As regards your diet, most markets now offer a wide variety of fresh, whole foods, as well as a host of other culinary delights beyond quickie restaurants. You can keep dried fruits, nuts and seeds in your desk, and you might see if there is room for a refrigerator in your workspace. If so, you can stock it with healthy snacks such as fruits, cut-up vegetables, yogurt and juices. This would make you less of a slave to vending machines and fast-food fixes.

For food outside work, I suggest sprucing up your breakfast. Get a higher-fiber cereal or some yogurt, and try to have fresh fruit with your meal. If strapped for time, consider taking advantage of the new crop of food delivery services that can bring healthful prepared meals to your location. On an off day, you might even consider a cooking class. This would help you learn to cook in less time, using healthier ingredients, and you could even take the leftovers to work the next day!

Other important points: Devote more time to physical activities and to getting the sleep your body needs. Start making slow-but-sure changes today. Consider setting up a series of rewards for goals set and achieved. Keep in mind that a lifestyle full of unhealthful habits has a way of setting itself on autopilot.

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: I am aware of the dangers of trans fats, but I am also concerned that some foods, like shortening, still use hydrogenated fats. Are these any better than the trans fats in partially hydrogenated shortening? One brand now uses “fully hydrogenated,” rather than partially. Is that better or worse for cooking? -- F.C., San Jose, California

DEAR F.C.: The quick explanation is that a fully hydrogenated shortening does not have any trans fats. Imagine a road stretching between an unprocessed, unsaturated liquid vegetable oil and a solid block of fully hydrogenated fat. On this road, partially hydrogenated fats are somewhere in the middle. The important issue here is that the process of partial hydrogenation is what creates trans fatty acids, or TFAs, which are unsaturated fatty acids that have an unusual structure causing a range of health problems in the body.

Partially hydrogenated oils used for deep-frying are different from those used in baking, breading or candy coatings. Blends with different proportions of TFAs might be more spreadable, have an increased shelf life or have some other desired feature, but the advantages of these artificial fats are all on the manufacturer’s side of the equation. They provide no health benefits for the human body.

Due to their negative health effects, and the lack of any upside, the Food and Drug Administration began requiring trans fats to be declared on food labels. With the advent of having to reveal the number of grams per serving, food processors sought other methods to make their fats spreadable.

In one method, known as interesterification (IE), food processors use oils together with fully hydrogenated fats and create a mixture with the desired characteristics. It’s not something you can do at home with a measuring cup. This type of reconfiguration involves shuffling fatty acids around on triglycerides using enzymes or chemical catalysts. Many hydrogenated -- but trans fat-free -- shortenings on the market are made this way.

IE has been available to food processors for a while, but since it was less costly to keep using partial hydrogenation, and there was no public outcry for alternatives, it was not widely used until recently. Fully hydrogenated products made using IE can have zero trans fats -- or, from a regulatory standpoint, less than 0.5 grams of trans fats per serving, meaning “no trans fats” can be declared on the Nutrition Facts label.

While this new family of shortenings with no trans fats is a positive development, the jury is still out as to whether the use of IE fats might also give rise to health issues. There’s also the possibility that fats naturally high in saturates, such as palm oil and coconut oil -- or even fully hydrogenated oils -- used in blends might be the way to go. Tropical oils, long suffering from a public-relations black eye, have now gotten their green card.

As for whether they’re any better or worse in the kitchen, IE shortening products have undergone performance testing, so you can expect them to be functionally comparable to the older versions. Just as there are brand-to-brand variances with other ingredients, you may need to do some testing to find the shortening that works best with your recipes. But it would be prudent to keep IE fats to a minimum, given that we don’t have a complete picture on their impact on health.

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.