saturated fats

Fat Facts 101: The Skinny on Saturated Fats, Polyunsaturated Fats, Monounsaturated Fats…

With all the buzz in the popular press lately about the vindication of
saturated fat and the recent publication of meticulously researched books promoting the same, now is a good time for a refresher on fats.

As health care professionals, we help guide our patients toward healthy diets and lifestyles, so it’s important that we have a sufficient working knowledge of some of the phrases we pepper the conversation with, such as saturated fats, polyunsaturated fats, monounsaturated fats, vegetable oils, etc.

Lipid chemists use the term “oil” to refer to lipids that are liquid at room temperature (like corn and canola oils), and the term “fat” when talking about ones that are solid at room temperature, (such as butter and lard). For simplicity’s sake, let’s refer to them the way most of our grandmothers did and call them all “fats,” differentiating only when necessary.

It’s not about black and white distinctions

One key thing to keep in mind is that no source of fat—either plant or animal—is completely saturated or completely unsaturated. All fats and oils are combinations of different types of fatty acids. Even lard, the mere mention of which might bring clogged arteries to mind, is actually higher in monounsaturated fatty acids than saturated ones. And of the monounsaturated fat that comprises lard, over 91% of it is oleic acid, the same fatty acid that predominates in olive oil, and which is widely regarded as heart-healthy. In fact olive oil often seems to be the only fat the divergent nutritional philosophies all agree on, whether they’re vegetarian, Paleo, low-carb, or simply focused on whole, unprocessed foods. So considering that lard is over 41% the same as olive oil, and even olive oil itself is about 14% saturated, Chef Emeril Lagasse has been right all along: pork fat does rule!

Another interesting fat breakdown involves the predominant fatty acid in cocoa butter, the saturated fat stearic acid (18:0). Since saturated fats are stable and do not easily oxidize (1), they are a safer bet for cooking and consumption than the polyunsaturated vegetable and seed oils, whose double bonds are susceptible to lipid peroxidation and rancidity. So maybe antioxidants and polyphenols might not be the only good reasons to snack on dark chocolate (2). The saturated fat in this decadent treat just might be good for you!

Getting to know the fats

The following chart shows the percentages of the different kinds of fatty acids that make up various common fats and oils.

Type of fat or oil

% Saturated

% Monounsaturated

% Polyunsaturated

Coconut oil

91

6

3

Butter

66

30

4

Lamb tallow

58

38

2

Palm oil

51

39

9

Beef tallow

49-54

42-48

3-4

Lard

44

45

11

Duck fat

35

50

14

Chicken fat (schmaltz)

31

49

20

Cottonseed oil

29

18

52

Peanut oil

16

56

26

Olive oil

15

73

10

Soybean oil

15

22

62

Sesame oil

15

41

43

Corn oil

14

27

59

Sunflower oil

13

18

69

Grapeseed oil

11

16

73

Safflower oil

9

11

80

Flaxseed oil

9

17

74

High oleic sunflower oil

9

81

8

Canola oil

7

65

28

Sources: USDA Agricultural Research Service National Nutrient Database for Standard Reference and Know Your Fats, by Mary Enig, PhD.

As you can see, some of the fats we’re accustomed to hearing called saturated—like beef or pork fat—actually contain either more monounsaturated fatty acids, or about the same amounts of saturated and monounsaturated. And two of the fats that are the most highly saturated do not come from animal foods at all, but are derived from plants, namely coconut and palm oil!

The misconceptions surrounding fats is, of course, about more than just semantics. With a constant stream of health news reaching the lay public through the mass media, it is prudent to speak with a complete and genuine understanding as to the true nature of fats, and with a strong grasp of specific food’s true composition. Only then will it be possible to have an intelligent national discussion about the role of fats in health, by having a solid understanding of the makeup of these fats, and how this influences their biochemical function inside the human body.

 

References:

(1) Glen D. Lawrence; Dietary Fats and Health: Dietary Recommendations in the Context of Scientific Evidence; Adv Nutr May 2013 Adv Nutr vol. 4: 294-302, 2013

(2) Nasiruddin Khan et al., Cocoa Polyphenols and Inflammatory Markers of Cardiovascular Disease; Nutrients. Feb 2014; 6(2): 844–880