Good fats vs bad fats Part 2: are saturated fats bad?

peanuts on a table

Fats, where they at?

Fats (or fatty acids) are fascinating. Humans eat fat, make fat and outsource the production of fat to bacteria living inside them. Take saturated fatty acids for example and more specifically, butyric acid [1].

It’s the main SFA in butter as well as the saturated fatty acids produced by bacteria in your colon (like Faecalibacterium prausnitzii [2]). These critters make it by eating the fiber you ate. Butyric acid is also found in the fermented beverage Kombucha [3].

Sugars and particular bacteria are purposely put in the drink so that the bacteria can eat the sugars and ‘poop out’ butyric acid which is partially why Kombucha tastes the way it does.

Saturated fatty acids: eat or avoid them?

To be clear, we’re talking about dietary saturated fatty acids. I emphasize this point because the effects of SFAs that we make from the foods we eat have different effects on our health than the SFAs we eat [4]. Dietary SFAs are present in high quantities in meats and fish [5].

You should not avoid these foods. Why? Long story short, the totality of evidence on dietary saturated fatty acids shows that they do ‘no harm’ to humans [6, 7]. The advice to avoid SFAs is decades and decades old and is strongly endorsed by prestigious institutions like the Harvard School of Public Health [8].

It’s one of the most pervasive, harmful myths in all of nutrition science. The notion that saturated fatty acids are inherently harmful belongs to the Nutritional Dark Ages.

What about fats my body makes?

Although counter-intuitive, the amount of saturated fatty acids in your diet isn’t proportional to the amount in your blood. In other words, you aren’t what you eat but what you make from what you eat. The ever-clever researchers Phinney & Volek et al. [9] summarize this by saying:

The results show that dietary and plasma saturated fat are not related […]

The next part of that quote makes a crucial point:

[…] increasing dietary carbohydrate across a range of intakes promotes incremental increases in plasma palmitoleic acid, a biomarker consistently associated with adverse health outcomes.

The more carbohydrates you eat, the more palmitoleic acid you find circulating in your plasma (plasma is component of blood). However, we don’t yet know how the type of carbohydrates you eat affects that relationship.

The fat mentioned here, palmitoleic acid, is a type of monounsaturated fat (MUFA). It’s presence, especially in higher quantities, isn’t a good sign due to it being associated with negative health outcomes.

The take-away point is that fat in the diet doesn’t equal the fat in your veins

Next up on in Part 3 of our Good fats vs bad fats series, we’ll discuss why the majority of vegetable oils like canola, safflower and soybean should be avoided.

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