Why Don't Total Fats and Types of Fats Add Up?

 

Question: Why Don't Total Fats and Types of Fats Add Up?

 

I know there are several websites that offer complete nutrition information for foods, which is very helpful. The problem is the information for fats. When I add up the amounts given for polyunsaturated fats, monounsaturated fats and saturated fats it doesn't equal the amount shown for the total fats. Shouldn't the three types of fats equal the total amount or are there some types of math errors going on?

 

Answer: The United States Department of Agriculture (USDA) provides a database of nutrition information for the foods we eat. Many sites, such as Calorie Count, use this information for creating their own calorie and nutrition databases. The USDA breaks down the macronutrients (fats, carbohydrates and proteins) into their various components and lists the amounts of each component as well as the total for each macronutrient.

When you search for a food such as avocados, you might look at the nutrition information and see the total fat grams is more than the sum of the three individual fatty acids (saturated fats, polyunsaturated fats and monounsaturated fats). Don't worry, while the total fats section of the nutrition charts may appear to be off, they're correct. The disparity isn't due to math errors (although rounding up or down may cause slight differences); the major reason is because there are other types of fatty substances present. These substances (phospholipids, glycerol and sterols) are included in the total fat, but they're not considered to be part any of the three fatty acid groups.

You won't find the phospholipids or glycerols listed in the nutrition information charts, however you will find the sterols. The best-known sterol is cholesterol, which is found in animals as well as the phytosterols (beta-sitosterol, stigmasterol and campesterol), which are found in plants.

By Shereen Jegtvig