When it comes to maintaining optimal health, one of the most important things to do is to stay informed. Getting age-appropriate screenings for diseases and conditions such as high blood pressure or cancer, for instance, can help you avoid the worst outcomes of either ailment. Understanding vaccination guidelines, the benefits of aerobic and anaerobic exercise, and learning how much sleep is needed to fully rest and replenish your body each night is also important.

But perhaps the most vital bit of information to stay on top of is keeping track of what's going into your body. That means paying attention to the ingredients and nutrition labels of the foods you and your family eat. "Learning how to read a nutrition label is important for those who want to increase their self-awareness around what they are consuming, be it for casual or medical reasons," says Tara Schmidt, lead registered dietitian for the Mayo Clinic Diet.

What are food nutrition labels? 

Food labels, sometimes called nutrition facts labels, are the black and white vertical rectangles you see on the side of food packaging. You'll find them on your favorite brands of milk, chips, soda, cereal, lunch meat and pretty much everything in between. Each food label is divided into two sections: the ingredients list and its nutritional value contents. 

"The ingredients list shows you what’s in a food," says Karen Collins, a registered dietitian and nutrition adviser to the American Institute for Cancer Research. She explains that such ingredients are listed in descending order by weight so that the first ingredient shown is the most prevalent ingredient and the last ingredient listed consists of the smallest quantity. Because of this, "it’s easy to check items like breads and cereals for whether a whole grain is actually listed first," she offers as one example.

The other part of the food label shows the nutritional value of the package's contents. Such information includes the macronutrient composition of the food such as the amount of carbs, protein and fats. "It also includes certain nutrient quantities per serving as well as sodium content and the amount of added sugars," says Dr. Uma Naidoo, director of nutritional and lifestyle psychiatry at Massachusetts General Hospital and the author of "Calm Your Mind with Food."

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Why do we have food labels? 

Such information can help you plan meals and snacks each day and prevent you from eating high quantities of foods with ingredients that are connected to negative health outcomes. "Nutrition labeling is required by the U.S. Food and Drug Administration (FDA) for most packaged foods," says Collins, but she explains that the labels are not required on raw fruits and vegetables. "And labeling on meat, poultry and eggs is regulated by the USDA, not the FDA," she adds.  

Naidoo says these labels were first implemented as part of a public health outreach program, "to promote healthy food choices appropriate to each individual consumer."

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How to read nutrition labels

Learning how to read these labels and which nutrients to look out for or avoid can be helpful. The first thing you'll find on the label is the serving size, followed by its number of calories and then the nutrients contained therein. 

All this information is based on a daily value (DV) of a 2,000-calorie diet, but "you may eat fewer or more calories a day depending on your age, gender, activity level, current weight and whether you’re trying to lose or maintain your weight," notes the Centers for Diseases Control and Prevention.

Paying attention to these labels in accordance with your diet means keeping track of how much of each serving you're actually eating. The serving size for many brands of breakfast cereal, for instance, is often only one cup, but many people eat two or three cups in a single sitting.

In general, Schmidt says it's best to pay attention to the presence of nutrients you know are good for you in each food such as vitamins A, B, C, D, E and K, plus minerals like calcium, magnesium, iron and potassium. She says it's also good to look at the total amount of dietary fiber included in each food and to avoid or minimize eating items that have a lot of added sugars, trans fat, saturated fat and sodium.

"It is also good to be guided by the number of calories, but remember not all calories are equal," cautions Naidoo. "For example, a medium-sized apple and a bag of potato chips may have about the same number of calories but are entirely different foods, as the apple is nutrient-dense and full of fiber and the potato chips are an ultra-processed food high in sodium," she explains. "That's why the other items listed on a nutrition facts label are also important to pay attention to."