May 22, 2014

When you're on a diet or trying to improve your health through nutrition, you spend a lot of time staring at the numbers at the sides of boxes, cans, and packages of food. And although there's been a lot of conversation about how the new and improved food nutrition labels will look when they go into affect in 2016 or so, there hasn't been as much discussion about whether or not the actual numbers on the box-the daily values, based on the recommended dietary allowances (RDA) for things like calories, fat, protein, carbohydrates, and various nutrients and vitamins-need updating too.

So are the numbers you're studying add up to a healthy diet? The Food and Nutrition Board, which is part of the National Academy of Sciences' Institute of Medicine and the body responsible for creating these values, says yes. Although many of the numbers in use were set in or before 1993, when food labels were introduced, the values still are an accurate measure of the average daily level of intake sufficient to meet the nutrient requirements of 97 to 98 percent of healthy people.

These numbers are, of course, an evolution. The board revises the RDAs every five to 10 years, and between revisions the latest nutrition research is under constant review. That means thousands of animal and human studies are pored over to be sure that the values suggested still hold up to the latest research. Because these numbers were devised from science from the start, you can generally expect small changes more than large ones. For example, one proposal for the new labels is to lower the allowance for sodium from 2,400 milligrams (mg) a day to 2,300 mg/day and to list the amount of added sugars in each serving.

Of course, all of the numbers you read should be taken with a grain or salt. (Or maybe sand, considering what the current stance is on sodium). Although two people who follow a 2,000-calorie diet will generally have the same sort of needs in terms of the percentage of fat, protein, carbs, and fiber they will want to take in, no two bodies or diets are ever alike. If you're running or doing lots of hot yoga, you may need extra sodium to replace that lost by sweat. If you're working to increase muscle mass, protein is a key nutrient. If you live in Alaska, you may need more supplemental vitamin D than a person who lives in sunny Hawaii.

The recommended dietary allowances are just that: Recommendations. The numbers stated are the amounts that scientists have found prevent nutrient deficiency and also overexposure. So while following these numbers will help you stave off scurvy and vitamin A toxicity, they aren't the only guidelines to take into account when planning your meals. Things like age, gender, activity level, and even where you live can influence the best diet for your body and your goals. For help fine-tuning an eating program, meet with a registered dietitian who can better customize your eating plan.

by Mary Hartley, R.D., for