Saturated fat is often considered unhealthy due to its potential to increase LDL-C. However, its effects on blood lipids may depend on the type of saturated fat consumed and other dietary components. This crossover study compared butter with palm stearin (a palm oil product that contains high levels of saturated fat).

The study

In this 8-week randomized, controlled, crossover trial, 24 people with normal cholesterol levels and a BMI <30 chose one of two diets before being randomized between a butter group and a palm-stearin group. The two diets were low-carbohydrate, high-fat (LCHF: 8/74/18% of calories from carbs/fat/protein) or high-carbohydrate, low-fat (HCLF: 60/22/18%).

For the first 3 weeks, the diet was based on canola oil. For the next 3 weeks, 40% of the fat was either butter or palm stearin. All meals were provided, and the diets were designed to be eucaloric (i.e., to promote weight maintenance). After a 2-week washout, the participants crossed over to the other fat source (butter or palm stearin).

The primary outcomes were triglycerides, HDL-C, LDL-C, and LDL particle type.

The results

The fat source (butter or palm stearin) made no difference with regard to triglycerides, HDL-C, or small LDL particles.

With butter, compared to palm stearin, LDL-C was 13.4% higher in the LCHF group and 10.8% higher in the HCLF group. This difference was attributed primarily to LDL I (large particles) and LDL IIa (medium-sized particles).

With butter, compared to palm stearin, oxidized LDL was higher in the LCHF group but not in the HCLF group.


Palm stearin is the solid fraction remaining after the fractionalization of palm oil. While palm oil is more commonly consumed and studied than palm stearin, the authors used the latter because it more closely matches butter’s saturated-fat content.

These results indicate that different types of saturated fat affect blood lipids differently. Butter’s myristic and lauric acids might increase LDL-C more than palm stearin’s palmitic acid.[1] Also, more of palm stearin’s saturated fatty acids are bound to the sn-1 and sn-3 positions, which may mitigate its adverse effects on LDL-C.[2]

The greater the number of LDL particles in the blood (LDL-P), the more likely it is that some will pass into artery walls, become oxidized, and kickstart plaque formation.[3] Therefore, to predict heart disease, LDL-P may matter more than LDL-C,[4][5] which is simply a measure of the amount of cholesterol being carried by LDL particles.

A recent meta-analysis we summarized found that low-carb diets may increase LDL particle size.

Every month we summarize over 150 of the most noteworthy health and nutrition studies. Other health categories related to this summary include:Try Examine+ for free to view the latest research in 25 health categories and the entire Study Summaries archive, access our Supplement Guides, and unlock the Examine Database. Plus, earn continuing education credits!

Get free weekly updates on what’s new at Examine.

This Study Summary was published on August 3, 2021.


  1. ^Elena Fattore, Cristina Bosetti, Furio Brighenti, Carlo Agostoni, Giovanni FattorePalm oil and blood lipid-related markers of cardiovascular disease: a systematic review and meta-analysis of dietary intervention trialsAm J Clin Nutr.(2014 Jun)
  2. ^Soek Sin Teh, Augustine Soon Hock Ong, Yuen May Choo, Siau Hui Mahsn-2 Hypothesis: a Review of the Effects of Palm Oil on Blood Lipid LevelsJ Oleo Sci.(2018)
  3. ^Tabas I, Williams KJ, Borén JSubendothelial lipoprotein retention as the initiating process in atherosclerosis: update and therapeutic implicationsCirculation.(2007 Oct 16)
  4. ^Allaire J, Vors C, Couture P, Lamarche BLDL particle number and size and cardiovascular risk: anything new under the sun?Curr Opin Lipidol.(2017 Jun)
  5. ^Otvos JD, Mora S, Shalaurova I, Greenland P, Mackey RH, Goff DC JrClinical implications of discordance between low-density lipoprotein cholesterol and particle numberJ Clin Lipidol.(2011 Mar-Apr)