Most of us think we know what’s good for us. The messages to eat more fruits and vegetables and consume foods with antioxidants are found in every form of media on a daily basis. Other sexy buzzwords that people mistakenly believe will lead to a healthy diet include natural, organic, antioxidant, polyphenol, fiber, free-range, vegetarian, herbal and similar terms.

But even when these types of foods make top 10 super-foods lists, diets limited to these can cause an unhealthy diet. To make matters more confusing, so-called experts disagree on what is healthy or what is bad. This can cause quite a dilemma for those sincerely seeking to maintain a healthy eating style.

Question: Are there any absolute rules relating to what constitutes a health-promoting eating style?

Answer: In the most basic sense, a healthful diet is a combination of foods that provides all of the essential nutrients needed for the body to stay healthy and within a calorie level that doesn’t cause a person to gain excess body fat. Without this first critical step, other nutrition efforts are nearly worthless or even potentially harmful.

Q: What is the difference between essential nutrients and other food components?

A: There are about 40 essential nutrients that we absolutely need for normal body functions. There are many other components in foods that are not absolutely essential, but may be good for us in the right amounts if you are consuming all of the essential nutrients.

For most essential nutrients, when one or more is too low in the diet for too long, symptoms are not obvious in the short term. Water is the exception, triggering thirst in most people within hours.

But most nutrient deficiencies will have no obvious effect on body function until we have significantly drained the body of the nutrient over time. This can take weeks, months, years or even decades, depending on the nutrient and the level of its intake. Once an essential nutrient falls below a critical level in the body, very serious and confusing health problems can begin.

Q: What are some surefire ways to sabotage a diet?

A: 1) Eat only foods the popular media deems to be healthy. 2) Eliminate all foods thought to be unhealthy. 3) Consume a limited variety of food to avoid the bad stuff.

By doing these things, you are highly likely to eventually end up missing one or more essential nutrients.

What can be confusing for the average person is that switching to some expert’s concept of a healthy diet can initially improve one’s health and feelings of well-being. However, changes that move someone’s diet too far in what seems to be the right direction can eventually cause health problems if the eating style is too low in any essential nutrient.

When symptoms of a nutrient deficiency begin, it is natural for a person to think that he or she is just not following "the plan" strictly enough.

An important element too frequently overlooked in maintaining healthful eating is being physically active.

Activity keeps calorie needs up so we can eat more food. When we can eat more food, it is much easier to get enough essential nutrients. When we have physical limitations that limit exercise, meeting nutrient needs within calorie needs can be challenging.

When this is the case, dietary supplements or fortified foods may be needed to ensure adequate intake of essential nutrients.

Alan Titchenal, Ph.D., C.N.S., and Joannie Dobbs, Ph.D., C.N.S., are nutritionists in the Department of Human Nutrition, Food and Animal Sciences, College of Tropical Agriculture and Human Resources, University of Hawaii-Manoa. Dobbs also works with University Health Services.