I’ve been promoting the OmagaQuant complete test as a way to calculate your Desaturase Indix (DI or DI18) to know your SCD1 levels. This is calculated by dividing your oleic acid (18:1) by your stearic acid (18:0). There are a lot of questions about what people’s numbers SHOULD look like. Ideally your DI should be low. But how low? I did a deep dive of the literature to pull the historical comparisons that are an apples-to-apples comparison with the OQ test: all red blood cell membrane phospholipids. Some of the papers compare healthy individuals with diabetic individuals. I am only presenting the healthy individuals here.
|US ’64||China ’92||Italy ’87||Finland ’87||US ’87||France 2014||Me Nov 2020|
|Dihomo-gamma LA (20:3n6)||2.2||1.5||1.0||1.3||1.56|
The foundational paper in this field was done at The University of Washington on healthy young adults in 1964.1 Diet isn’t mentioned but it’s fair to assume they were eating a fairly standard American diet of flour, potatoes, sugar, dairy, meat, vegetables and fruit. Probably some alcohol. This paper established the relative ratio of the major classes of phospholipid – phosphtidylcholine, phosphotidylserine and phosphatidylethanolamine – and the fatty acid composition of each class. Which is fun because in order to compare it to the OmegaQuant test you actually have to put all of the numbers into a spreadsheet and do the math…
The next paper2 is from China looking at the fat composition of children eating rapeseed oil, not very much: “fat intake could even be as low as 11% of total calories, rapeseed oil is the main source of edible fat, contributing about 44% of the total fat intake.” “The main staple food is wheat, the main vegetables are spring potato and cabbage. Sometimes bean curd, seldom pork, and never fish or dairy are consumed.” This population has the highest amount of saturated fat, the lowest DI and the highest ratio of Omega 6 linoleic acid to omega 6 arachidonic acid of any population studied.
The next study3 has the three populations from 1987 – one each in Italy, Finland and the US. The participants were all men working in either farming or forestry who consumed less than 100g of alcohol per day and who smoked less than one pack of cigarettes. We are given a very brief synopsis of the physical characteristics and regional diets. They actually analyzed the foods being eaten! The Italians (BMI 26.3) get 14% of calories from alcohol and much of their dietary fat from olive oil. They had the least linoleic acid of anyone studied, presumably the oleic acid in their diet was substituting for PUFA. They have the highest DI by a LOT but it’s hard to tell if this is from dys-regulation or from dietary oleic acid. My guess is the second. The Finns (BMI 25.9) eat the most saturated fat, have the lowest BMI, the lowest body fat percentage and a DI of a very respectable 1.1. The Americans (BMI 26.9) have the highest BMI by a little but the highest body fat percentage by a lot. They eat triple the PUFA of the Europeans, but they are not dys-regulated yet. At 7.3% PUFA they are approaching the threshold, but their DI is still great at 1.1.
The French study4 gives very little information about the ages, gender or diet of the patients. We know they are non-diabetic. I presume they are eating baguettes and soft cheese and drinking wine.
The final column is me. I grew up in a household with only margarine, no butter. Salad was served at every dinner, which meant Kraft Thousand Islands dressing. My dad maniacally cut every bit of visible fat off of the meat we were served. I learned to use Thousand Islands dressing as a steak sauce since the steak was lean and dry. I ate school lunch. I am dys-regulated. That’s OK. The long term goal of this blog is to see if we can fix people like me.
I decided against including this British Study…5 The fat numbers just don’t add up. I have more questions than answers. For instance, they reported only 1.65 percent arachidonic acid but 13% 22:4n6? And nervonic at 3.3%? Something just seems off.
- 1.Ways P, Hanahan DJ. Characterization and quantification of red cell lipids in normal man. Journal of Lipid Research. Published online July 1964:318-328. doi:10.1016/s0022-2275(20)40200-7
- 2.Laryea MD, Jiang YF, Xu GL, Lombeck I. Fatty Acid Composition of Blood Lipids in Chinese Children Consuming High Erucic Acid Rapeseed Oil. Ann Nutr Metab. Published online 1992:273-278. doi:10.1159/000177729
- 3.Dougherty RM, Galli C, Ferro-Luzzi A, Iacono JM. Lipid and phospholipid fatty acid composition of plasma, red blood cells, and platelets and how they are affected by dietary lipids: a study of normal subjects from Italy, Finland, and the USA. The American Journal of Clinical Nutrition. Published online February 1, 1987:443-455. doi:10.1093/ajcn/45.2.443
- 4.Koehrer P, Saab S, Berdeaux O, et al. Erythrocyte Phospholipid and Polyunsaturated Fatty Acid Composition in Diabetic Retinopathy. Stitt A, ed. PLoS ONE. Published online September 4, 2014:e106912. doi:10.1371/journal.pone.0106912
- 5.Patel PS, Sharp SJ, Jansen E, et al. Fatty acids measured in plasma and erythrocyte-membrane phospholipids and derived by food-frequency questionnaire and the risk of new-onset type 2 diabetes: a pilot study in the European Prospective Investigation into Cancer and Nutrition (EPIC)–Norfolk cohort. The American Journal of Clinical Nutrition. Published online September 22, 2010:1214-1222. doi:10.3945/ajcn.2010.29182