If you peruse USDA’s FoodData Central website1 you’ll see a number of subcategories under several of the essential nutrients.
For example, an entry for almonds in FoodData Central shows values for vitamin E (alpha-tocopherol), beta-tocopherol, gamma-tocopherol, and delta-tocopherol.
The National Institutes of Health Office of Dietary Supplements2 defines vitamin E like this:
“Vitamin E is found naturally in some foods, added to others, and available as a dietary supplement. Vitamin E is the collective name for a group of fat-soluble compounds with distinctive antioxidant activities.
Naturally occurring vitamin E exists in eight chemical forms (alpha-, beta-, gamma-, and delta-tocopherol and alpha-, beta-, gamma-, and delta-tocotrienol) that have varying levels of biological activity. Alpha- (or α-) tocopherol is the only form that is recognized to meet human requirements.”
NRC also lists the nutrient requirement for vitamin E in dogs and cats as specifically for alpha-tocopherol in tables 15-3, 15-5, 15-8 (dog life stages), and 15-10, 15-12, and 15-14 (cat life stages) in Nutrient Requirements of Dogs and Cats (2006).
As part of our ongoing efforts to ensure data integrity, vitamin E values are updated to reflect alpha-tocopherol content only (and not other tocopherols or tocotrienols) as ingredients in the database undergo verification. Therefore, you may notice changes in the vitamin E content of some ingredients.
Similarly, folic acid (vitamin B9) is part of a family of nutrients. Beef liver in FoodData Central gives a total folate value, as well as the individual components folic acid, folate (food), and folate DFE1. DFE refers to dietary folate equivalent, which incorporates contributions from both folate and folic acid where mcg DFE = mcg naturally occurring folate + (1.7 x mcg folic acid).
NIH2 offers this explanation:
“Folate is a B-vitamin that is naturally present in many foods. Your body needs folate to make DNA and other genetic material. Your body also needs folate for your cells to divide. A form of folate, called folic acid, is used in fortified foods and most dietary supplements.
The measure of mcg DFE is used because your body absorbs more folic acid from fortified foods and dietary supplements than folate found naturally in foods. Compared to folate found naturally in foods, you actually need less folic acid to get recommended amounts. For example, 240 mcg of folic acid and 400 mcg of folate are both equal to 400 mcg DFE.”
Turning again to NRC for guidance specific to dogs and cats, we find that NRC appears to use the terms folate and folic acid interchangeably when 00 both folic acid and folate from food. However, it is worth noting that in human nutrition, the folic acid (supplemented) component is regarded as providing more bioavailable vitamin B9 than that provided by the natural folate form found in food. In dog and cat diets where the entire folic acid requirement is provided by natural foods (containing folate rather than folic acid), it may be prudent to provide 1.7 times more than the minimum requirement listed for folic acid.
1https://fdc.nal.usda.gov/index.html
2https://ods.od.nih.gov/factsheets/VitaminE-HealthProfessional/