My challenge: meet all the daily nutrition standards in the federal government's guidelines without taking a multivitamin or other supplement.

My challenge: meet all the daily nutrition standards in the federal government's guidelines without taking a multivitamin or other supplement.

My accomplice: Danielle Omar, a registered dietitian based in Fairfax, Va.

As I popped my multivitamin one morning, I got to wondering how hard it would be to consume all the vitamins, minerals and other nutrients recommended by the USDA's Dietary Guidelines for Americans without the help of that daily pill. Like many people, I've used my multivitamin as a safety net to ensure that my body gets what it needs even when my diet isn't all it should be.

Talking with experts and reading medical studies has made me question whether nutrients delivered in supplement form pack the same punch as those same nutrients delivered via real food. If possible, I'd prefer to go the real-food route. But how can I fit everything in without consuming more calories than I should?

Danielle Omar was curious, too, and joined the challenge with gusto. She proposed creating a day's menu for a hypothetical 35-year-old, 5-foot-4-inch woman who weighs 130 pounds and exercises three times a week. (Not quite my profile, but Omar thought it was a good model to use.) That woman would require 1,800 calories per day to maintain her weight. That ought to be do-able, right?

The project proved more challenging than we expected. Omar took a first pass using her general knowledge to devise a basic plan that she figured would cover all the nutritional bases. She aimed to exclude processed foods and all caloric beverages other than milk. She tried not to cop out by offering just a salad for lunch, opting instead for a turkey sandwich and a cup of soup.

When she crunched the numbers, though (using the calculator at Fitday.com), she found that her plan was out of whack. She wasn't offering nearly enough iron, Vitamin D or potassium, and she'd gone way overboard on sodium: about 4,500 milligrams more than the recommended limit of 1,500. The potassium/sodium mix is particularly important in regulating hypertension: Too much sodium raises blood pressure in most people, while potassium lowers it.

So Omar went back to the drawing board. Her revised menu is represented in the accompanying graphic.

At first it looked like a lot of food. But on closer inspection it seemed awfully meager, more like a weight-loss diet than a maintenance regimen.

That piece of salmon weighs four ounces BEFORE it's cooked; it's a lot lighter by the time it reaches your plate. And measure out that half-cup of rice: It's a lot smaller than the portion most of us are accustomed to. There's no wiggle room, either. Squeezing all those nutrients into 1,800 calories means no dessert and no alcohol, not even a glass of wine with dinner.

And even with eliminating cheese and substituting low-sodium foods for regular versions wherever possible, Omar still couldn't wrestle the sodium down to the target; her menu contains more than 1,000 more milligrams of sodium than the recommended limit.

As a professional dietitian, Omar found this exercise eye-opening. Here are some tips she learned, if you want to try the no-supplement route yourself:

Resign yourself to eating some processed foods, such as cereal and bread, but be selective. When choosing a processed food, Omar suggests, be sure it's helping you meet your goals by delivering fiber, protein or potassium; many processed foods are fortified with calcium, folic acid and other needed nutrients. Omar says she couldn't have met the goal for iron without trading traditional slow-cooking oatmeal, which she would have preferred for its lack of sodium, for packaged microwave oatmeal. Sneak in as many fruits and vegetables as you can. Add spinach to your sandwich; dip baby carrots in your hummus. But be aware that you're still likely to fall short: For instance, it would take 11 bananas to meet the target for potassium. (Beans, potatoes and orange juice are other prime sources of this nutrient.) Use ground spices and herbs, which are surprisingly rich sources of such essentials as iron and potassium. Be aware that the daily values listed on food packages are based on a 2,000-calorie diet. Use the percentages listed there just to ballpark your intake of calories, fat, fiber and other items. Go to www.health.gov/DietaryGuidelines to estimate your own nutritional needs.

In the end, Omar concluded that supplementing your diet may be prudent, particularly when it comes to Vitamin D, calcium, Omega-3 fatty acids and folic acid.