DEAR DR. BLONZ: At what age is a person considered an adult as regards nutrient requirements? My daughter is 14, and I want her to take a supplement because of her sketchy eating habits. I developed osteoporosis -- it is now under control, but I do not want this for her. -- F.M., Phoenix

DEAR F.M.: The answer of when to grant “adult” status for nutrient levels varies based on a number of factors. For one thing, every child grows at their own rate; a look back at class pictures will show how growth through childhood, adolescence and adulthood can vary from individual to individual.

Broadly speaking, a child is not a miniature adult. At some time during the adolescent years, ages 13 through 17, the child transitions into their adult body. In some, this occurs rapidly, as evidenced by the frequent need to buy that next-larger size of clothes. (This phase often, but not always, coincides roughly with puberty.)

Pharmaceutical companies must consider this adult/child issue quite carefully. Medication dosages are based on how the drug is expected to act in each given age group, so it is essential to test a given drug on all age groups for which it may be prescribed. Some medications direct you to use adult dosing from age 12 on, while other medicines have separate guidelines up to age 18. That is another reason why it is always important to read and follow directions on medications.

As far as vitamins and minerals are concerned, food labels’ “daily values” are set for adults and children over the age of 4, by which measure your daughter is most definitely in the “adult” category.

But rather than encouraging supplements as the answer to poor eating habits, do your best to educate your daughter regarding the importance of good food and good nutrition -- especially the need for calcium and other minerals for her bones. Young men and women need to understand that our bones are constantly made and remade, and that the first 35 years of life make up the critical period when our bones tend to gain more mass than they lose. This switches during the midlife period, so you want a healthy bone mass in place before the “drain” takes over. Physical activity can help optimize skeletal health throughout life.

If your daughter is not going to be getting all she needs from her diet, a vitamin-mineral supplement might be an alternative, but is not a true solution. Food should always be the priority. Keep in mind that the example you and other adults set is the seed that takes root as your daughter transitions to adulthood. Avoid the “do as I say, not as I do” paradigm, as kids tend to see through this.

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: Much of the advice I have received about managing my digestive issues has mentioned the need to avoid certain food combinations. This advice is based on the logic that “bad” combinations overwhelm the digestive system, preventing the foods’ nutrients from being properly absorbed and contributing to digestive upsets. Is this based in fact? -- O.C., New York City

DEAR O.C.: Foods are a complex combination of different types and sizes of nutrients and non-nutrient components. Our digestive system, by contrast, likes things simple. For our bodies to absorb foods’ components, foods must be taken apart piece by piece. Think of our digestive system as a “disassembly” line.

The digestive tract workers are enzymes: chemicals with specific abilities to pull apart the proteins, carbohydrates or fats in food. Enzymes are the epitome of specialization, in that each performs one action on one type of nutrient. For example, one enzyme splits big proteins into smaller pieces, while others break the small pieces into their amino acid parts. Similar-staged disassembly occurs with complex carbohydrates and fats.

We rely on over a dozen different enzymes to digest a typical meal. The beauty of the human digestive system is that it’s designed explicitly for that mixed diet. That means the advice you were given was off the mark. Since different food components get handled in different areas and by different enzymes, we don’t have to eat our foods one at a time.

Digestion begins even before the first bite: The cephalic phase starts when we see, smell or even think about food. We have all experienced our stomachs rumbling in anticipation of a meal. This is also connected to our tendency to eat meals at the same time most days, and becomes especially noticeable when a meal is delayed. In the cephalic phase, acid gets released in the stomach in preparation for the food about to arrive. In the mouth, chewing increases a food’s surface area and mixes it with our enzyme-containing saliva to facilitate the actions ahead.

The stomach is our high-acid, muscular churning compartment that denatures proteins. The acid environment activates certain enzymes involved in protein digestion, and it can also help destroy unwanted microorganisms hitchhiking on the food. The stomach is spared from self-digestion by a protective layer of mucus. Those with the misfortune of having gastroesophageal reflux disease, or GERD, have experienced the discomfort of the stomach acid splashing up into the esophagus, where that protection is not present. (More on GERD at b.link/7kae7.)

As the stomach completes its work, the partially digested mass of food, referred to as chyme, leaves through the pyloric sphincter. As the chyme departs, it is immediately doused with the body’s own antacid solution. Your meal is now in the small intestine, a veritable enzyme factory where the central part of digestion and absorption occurs.

Returning to your question, many of us may have found that certain foods or food combinations work best for us. Consider that we are creatures of habit, and our bodies do acclimate to the way we eat.

When making major changes in what we eat, it makes sense to do things slowly, but this advice is based more on our bodies’ habit-bred efficiency than a defect of human digestion. There appears to be no physiological reason to refrain from including a variety of foods at every meal.

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: What are your thoughts about personal qualities that might determine who will be successful at losing weight? -- S.O., Los Angeles

DEAR S.O.: An instructive paper in the American Journal of Clinical Nutrition (November 1990) comes to mind, which examined three different types of women. The first group lost weight, but then regained it; they were called the relapsers. The second group lost weight and kept it off; these were the maintainers. The third group was the control group, who remained at the same “non-obese” weight.

The researchers looked at the subjects’ weight histories -- including prior attempts at dieting -- and their childhood food experiences, meal and snacking patterns, emotion-related eating, and how they typically handled troubling situations. The paper revealed some interesting differences that address your question.

The relapsers were more likely to take appetite suppressants and participate in formal weight-loss programs. More relapsers skipped breakfast, and they often went on restrictive diets that denied them many of the foods they enjoyed. In comparison, most maintainers did not seek help from support groups, diet partners or health professionals. If using the same approach to weight loss, relapsers adapted their lifestyle to the program, while maintainers usually tailored the program to fit their lifestyle.

During the weight-loss period, both maintainers and relapsers reported stressful events involving family or careers. Maintainers tended to confront and solve problems, while relapsers often resorted to avoidance behaviors such as eating, sleeping and/or drinking more, or merely wishing that the problem would go away.

Another significant finding was that 90% of the maintainers, versus 34% of the relapsers, engaged in exercise at least three times a week. Studies often report that the body decreases its baseline metabolic rate (the rate at which calories are burned at rest) when weight is lost. This unfortunate decrease can slow the rate of weight loss and help explain why it is hard to keep pounds off. Regular exercise helps counter this decrease, in addition to burning more calories.

These findings suggest that personality can be an essential determinant for long-term success with weight reduction. It also tells us there’s no such thing as a one-size-fits-all diet plan. Most commercial programs suggest their methods and products work for anyone, but their main accomplishment may only be a short-term loss of pounds. People seeking treatment for a weight problem should be screened and guided into a program that suits their personality.

One hopeful message here is that a relapser can become a maintainer. Some maintainers in this study had been relapsers at one time. New habits and behaviors had to become established for that switch to occur. For example, no longer would working out be a chore only done to lose weight; rather, it was understood and internalized as a fundamental element of a new, more healthful lifestyle.

While reflecting on this, it’s essential to appreciate that realistic goals are a part of the process; you may never drop you as low as you want to go. Healthy people often carry some extra weight. Likewise, simply because someone happens to be thin is no guarantee that they are better off.

Health is as health does, and this holds true at any weight. Society-imposed pressures to achieve a particular body type do little to promote our physical and mental health and well-being.

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.