A recent survey of nearly 700 Americans showed that 72 percent believe they are healthy eaters, yet government data proves otherwise.

The USDA recently revealed that Americans get plenty of protein and carbohydrates, but often fall short on key nutrients such as magnesium, potassium and vitamins C and E.

"Fifty years ago, we only recognized extreme cases of vitamin deficiencies, like scurvy, which is caused by a lack of vitamin C," said Carroll Reider, MS, RD, Nature Made vitamins director of scientific affairs and education. "Science has advanced. We now know that even small amounts of vitamin deficiencies hurt us much more than people realize."

While most Americans appear well fed, a key question is: Are you nutritionally fit? To assess your nutritional condition, Reider posed the following questions:

Do you shun the sun? People who wear sunscreen, live in northern climates or have darker skin may not receive optimal levels of vitamin D, which is made following exposure to sunlight. Vitamin D helps the body absorb calcium and may also promote ovarian, breast, prostate, heart and colon health. Reider suggests 1,000 IU of vitamin D daily for people who spend most of their time indoors and those who don't synthesize vitamin D easily, such as darker- skinned individuals and the elderly. Vitamin D food sources include milk and fatty types of fish; however, it is hard to achieve optimal intake through food alone. It is also available in supplement form.

Do your meals lack color? Does dinner typically consist of meat, starch and the same green vegetable? For optimal health, add more colors to your diet. Vegetables such as steamed carrots, peppers and red cabbage add vibrant hues to the dinner plate while citrus wedges brighten the standard bed of greens. Eating a variety of fruits and vegetables maximizes nutrient intake and provides antioxidants, which help fight free radicals that may cause premature aging. "A multivitamin formulated for your age and gender is also a good way to compensate for dietary imbalances," Reider said.

Is fish a regular dish? The American Heart Association recommends two servings of fish per week. Reider suggests salmon and tuna, which are rich in omega-3 fatty acids. Some studies suggest omega-3 fatty acids may promote heart health. Other sources include walnuts, flaxseed or vitamins.