Saturated fats are not all the same... Comparing 15 fatty acids, Pentadecanoic acid outperforms DHA

It is commonly known that unsaturated fats are healthy and saturated fats are harmful. A video from the Doctor Dingyo channel explains that this statement is half right and half wrong. While it is true that unsaturated fats are healthy, saturated fats are not just one or two types; there are many different kinds, creating a wide spectrum. The video's core concern is that grouping all saturated fats into a single substance to support the lipid hypothesis—which claims saturated fats increase LDL cholesterol, causing atherosclerosis and cardiovascular death—may be inaccurate.

15 Fatty Acids: Most Effects on LDL, Cardiovascular, and Mortality are Consistent

The video compared 15 different fatty acids. Unsaturated fats were divided into four types: Omega-3 (further split into EPA and DHA), Omega-6, and Omega-9. Saturated fats were broken down into nine types: short-chain fatty acids, medium-chain fatty acids, the 12, 14, 16, and 18-carbon long-chain fatty acids, two types of odd-chain long-chain fatty acids, and very-long-chain fatty acids. Dietary cholesterol and industrial trans fats were also added. For Omega-3, the video looked at EPA and DHA found in fish oil, excluding alpha-linolenic acid found in perilla oil.

As a result, the effects on raising or lowering LDL cholesterol and the effects on cardiovascular health, mortality, and anti-aging were almost identical, except for about four types. The video explains that roughly 80% of the results are consistent. Omega-9 (oleic acid) and Omega-6 (linoleic acid), which lower LDL cholesterol, also lower cardiovascular disease and total mortality. Conversely, palmitic acid and trans fats, which raise LDL cholesterol, also raise cardiovascular disease and mortality rates in almost direct proportion. Among saturated fats, pentadecanoic acid, which is the healthiest, outperformed DHA. The video concluded that odd-chain saturated fats, very-long-chain fatty acids, and short-chain fatty acids are somewhat beneficial even as saturated fats; dietary cholesterol and medium-chain fatty acids are neutral; and the remaining 12, 14, and 16-carbon chains are the problem.

The video explains that although coconut oil is high in saturated fat, it is not that bad for health because most of it consists of medium-chain fatty acids, though it does contain some palmitic acid. Palm oil was viewed as being close to the worst oil because, while its saturated fat content is lower than butter, the palmitic acid component is overwhelming. Myristic acid is explained to raise LDL cholesterol significantly, but it primarily raises large LDL and increases HDL by a similar amount, so it does not raise cardiovascular mortality that much.

Why LDL and Mortality May Seem Divergent: Confounding Variables and ApoB

The video divided the reasons why results sometimes diverge from LDL cholesterol into three main categories, explaining that the first and second reasons stem from issues with the LDL cholesterol metric itself. The first is confounding variables. In both the Danish cohort and another cohort, mortality is lowest at an LDL cholesterol level of around 130–140, and if it is below 130, mortality actually rises. However, this is not because low LDL cholesterol causes death, but because the results include cases where LDL cholesterol dropped first due to frailty, cancer, declining liver function, or malnutrition before death occurred. The video noted that in Mendelian randomization studies, where there is no need to consider confounding variables, LDL cholesterol continues to contribute to mortality regardless of age.

Second, LDL cholesterol is not a perfect metric. The video compared measuring LDL cholesterol to measuring the weight of vehicles on a road, while ApoB is like measuring the number of vehicles. Since traffic accidents occur in proportion to the number of vehicles rather than their weight, one must look at ApoB. A representative example is Omega-3. Omega-3 is neutral or slightly raises LDL cholesterol, and DHA raises LDL cholesterol. Therefore, looking only at LDL makes it seem unhealthy, but the explanation is that Omega-3 produces more large LDL and lowers triglycerides, and when measuring ApoB, it is found to lower ApoB. The video specifically mentioned that it has been proven that EPA lowers ApoB, thereby preventing cardiovascular disease. The video concludes that if these two factors are adjusted for, the impact of most fats on health occurs through ApoB, meaning the lipid hypothesis is almost correct.

Palmitic Acid Has Additional Toxicity, Stearic Acid is Neutral

The third reason is the part where fats themselves affect health through independent pathways, bypassing LDL cholesterol or ApoB. The video explains that Omega-3 and pentadecanoic acid have additional benefits, while palmitic acid has additional harm. Palmitic acid has additional toxicity beyond its contribution to mortality via raising cholesterol, and that is ceramide. The video mentioned that in a previous video, it was explained that ceramide consumed through processed foods, etc., attacks the pancreas and leads to diabetes. It summarized these independent pathways as: 1st, the ceramide pathway of palmitic acid; 2nd, Omega-3, especially EPA; and 3rd, ketone bodies, very-long-chain, and pentadecanoic acid.

Regarding Omega-6, while some perceive it as a poison, the video states that no matter how much one searches, there is no evidence that it is bad for health. The explanation is that Omega-6 enters cell membranes to provide membrane fluidity and increases insulin sensitivity, and it noted that many studies have consistently reproduced the result that replacing butter with cooking oil reduces coronary mortality by 21%.

Stearic acid is the 18-carbon saturated fatty acid found in abundance in cocoa butter. Although it differs by only two carbons from the 16-carbon palmitic acid, the result was neutral. This is because while it originally raises LDL cholesterol slightly, it is rapidly converted into oleic acid upon entering the body. The video explained that eating chocolate is like the cocoa butter within it being converted into olive oil; because it tries to raise LDL but then turns into olive oil and lowers it again, the result is neutral.

For Chocolate, Check if it is Free of Palm Oil and Sugar

The video says the claim that chocolate is good for health also stems from it being rich in stearic acid. However, it explained that in South Korea, a product can legally be named "chocolate" if it contains 18% or more cocoa butter, while milk chocolate or semi-chocolate can be made with 100% palm oil without adding cocoa butter. It added that if made cleanly with pure cacao fruit without adding sugar, the maximum cocoa butter fat ratio is about 40%. The video advises that most commercially available chocolates contain palm oil, so instead of looking at how much cocoa butter is in it, one should choose by checking if it is free of palm oil and sugar. It noted that the reason pure chocolate is good is due to the antioxidants in the cacao fruit rather than the fat itself, and while chocolate without palm oil and sugar should not be eaten in large amounts or too frequently, it is much better.