Anatomy and Physiology of A Nutrition Label

August 6, 2012

The anatomy of a nutrition label is fairly obvious – serving size, calories per serving, nutritional components with percent of daily allotment for each, and ingredients. The physiology (or what the label can do for you) is a little more tricky depending on your nutritional needs. While not all-inclusive, this blog will discuss some examples of how to get the most useful information for your specific needs from a nutrition label.

So how does a nutrition label work for you? Besides listing the serving size, nutritional components in terms of percent of daily allowance, and ingredients, the label can be a guide to helping you plan your diet. Most nutrition labels are based on a 2,000 calorie per day diet. Some will also list other daily allowances. You will need to determine your calorie allowance and adjust the serving size to meet your needs. You may also need to take into account specific medical conditions and the nutritional needs for those conditions when considering your meal choices.

Nutrition Label

BBQ Chicken California Pizza

The above is the label for a California Pizza (BBQ Chicken) and has daily values based on a 2,000 calorie per day diet but also gives some information for a 2,500 calorie diet. Additional nutritional information can be calculated as a fraction or percent of the 2,000 calorie diet.

I will use the example of a 1,500 calorie diet to evaluate the nutritional value of this slice of pizza. Since 1,500 is three-fourths or 75% of 2,000, the nutritional components in this label for fat, saturated fat, carbohydrates, and dietary fiber need to be multiplied by 0.75 to get the correct values for a 1,500 calorie diet.

If your diet is based on 1,500 calories per day, your intake of fat should be less than 48.75 grams of fat. How was this number derived? Since 1,500/2,000 = 0.75, you need to multiply 0.75 by 65 grams to get the number of grams of fat for your diet. This amount is 48.75. Since one serving of this pizza is only 10 grams it is not a bad choice for a meal since it will be 20.5% of your fat allotment for the day (10/48.75 = 20.5). Be aware, though, that even though this serving only provides 20.5% of your fat calories, it is still a high fat food because 90 calories of the 310 calories (90/310) or 29% is fat! Additionally, the saturated fat from one slice would be a little on the high side. On a 1,500 calorie diet, your allotment of saturated fat would be 0.75 x 20 or 15 grams per day. This serving provides one-third of your daily allotment of saturated fat (5/15 = 1/3) which means you would need to be more careful about eating any other sources of fat with this meal! Saturated fat needs to be modified beyond this amount in someone with heart disease or other circulatory conditions, so for those persons this slice of pizza might not be a good meal choice.

You should note that this slice of pizza only has 1 gram of fiber which is extremely low if you want to meet your dietary guidelines. On a 1,500 calorie diet you need to eat 0.75 x 25 or 18.75 grams of fiber per day. This slice only provides 1/18.75 or 0.5% of you daily need! Fiber is an important nutrient for persons with constipation, irritable bowel syndrome, and other gastrointestinal conditions.

Sodium is an important nutritional parameter to monitor especially if you have high blood pressure. Many doctors recommend less than 2,400 milligrams of sodium per day, which is not calorie-dependent. This slice of pizza has 810 milligrams or 34% (810/2,400) of your daily allotment of sodium! This is a poor choice for a person with hypertension!

Additional things to notice on this food label include the vitamins A and C. These are in very low amounts not providing much nutritional benefit. The amount of calcium in this slice of pizza is not bad at 25% of the daily allowance! Please note that children and pregnant and breastfeeding women need to eat higher amounts of calcium than those listed on the label. Also, most individuals eating less than 2,000 calories per day will need vitamin supplementation.

Vitamins and minerals such as calcium are based on a minimum daily requirement independent of the number of calories consumed so these values can be used directly from the label without additional calculations when meal planning.

These are just some examples of how a nutrition label can assist you in making food choices that are in line with your nutritional needs based on your specific health and medical conditions.

There are many sources on the Internet that can help you calculate your dietary needs. Seek the advice of your primary care provider for your nutrition prescription and a registered dietician or nutritionist to help you make food choices that are in line with that prescription!

Feel free to leave comments or questions. I will answer some questions below or if they require a lengthy response, I will address them in a future blog.

To your health!

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