Wednesday, September 17, 2014

Which Micro- & Macronutrients Intakes Are Associated With High HDL Levels? Study Shows Magnesium & Folate Are, High Carbohydrate & Total Animal Fat Intakes Are Not!

The advantage of HDL is its stability that reduces the risk of plaque build-up in the intestinal wall, which is clogged by the remnants of oxidized LDL and causes heart disease & co.
First things first: We are not talking about "hard experimental evidence" as you could generate it in a randomized controlled trial in a metabolic ward. The data I am reporting today is from a cohort with 1,566 participants with extensive lipid phenotype data completed the Harvard Standardized Food Frequency Questionnaire to determine their daily micronutrient intake over the past year - an epidemiological study that used stepwise linear regression was used to separately evaluate the effects of dietary covariates on adjusted levels of HDL-C, HDL-2, HDL-3, and apoA1.

Interestingly, this is the first study with a quality data-set that determined the association between specific dietary micronutrients with HDL-C, HDL-2, HDL-3, and apoA1, and how these dietary associations differ across the various measures of HDL - not just one.
Learn more about HDL, cholesterol, heart health & co at the SuppVersity

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To identify the HDL-promoters in the diet, the scientists use demographic and clinical variables in the base model. What they found was that numerous dietary intakes increased total HDL-C variance.
The results of their stepwise linear regression model in Table 1 indicate - probably for some people much surprisingly - that all alcohol intake levels were positively associated with HDL-C.
"In addition, magnesium, folate, and the saturated fat, myristic acid (14:0), were all positively and independently associated with HDL-C. Carbohydrate intake, iron, and % of fat derived from animal sources were each negatively additive for HDL-C." (Kim. 2014)
Similar effects from dietary intakes were observed for HDL-2, of which we know that it is decreased in women with rheumatoid arthritis (Arts. 2012) and individuals with other inflammatory diseases (including metabolic syndrom) and associated with a slightly higher reduction in acute myocardial infarction risk than "regular" HDL in several studies (Salonen. Salonen. 1991; Stampfer. 1991; Buring. 1992; Gaziano. 1993) for all alcohol intakes, magnesium, folate, and myristic acid (14:0), eicosapentaenoic acid (20:5, a ω-3 EPA), all of which were positively and independently associated with HDL-2 levels.
Table 1:  Best-fit model from stepwise linear regression predicting HDL-C levels using dietary intake data (Kim. 2014)
The opposite was the case for arachidonic acid (20:4, an ω-6 ARA), carbohydrate and iron intakes, which were both negatively associated with HDL-2 (see Table 1).

Don't forget to put things into perspective!

And just to make sure, I don't get angry emails from bulletproof coffee drinkers: Your coffee is fine, the content of the only "good" saturated fat, i.e. myristic acid, happens to be especially high coconut oil (41%; Sodamade. 2013) and relatively high in butter (12% independent of whether it's grass-fed or not; Couvreur. 2006) - surprised? Not really, I guess. As a SuppVersity reader you are by now aware that the bad reputation coconut oil and butter have for being mostly saturated fats is no longer supported by contemporary scientific evidence (Dias. 2014).

And with respect to the total animal fat intake - for the average Westerner that's a good measure of how much processed meat he / she eats, so I would not overrate the small negative association (1/80 of the one of having a ton of carbohydrates in your diet!) the scientists found in the study at hand.
Eggs are unquestionably and exception from the "animal fat" is bad for HDL rule | learn more.
Bottom line: With the exception of folate, which has previously not been reliably associated with increases in HDL, let alone speficic HDL subfraction, the improvements with alcohol, magnesium and EPA are not exactly news. The same is true for the decreases in response to increased intakes of (all) animal fat, arachidonic acid, carbohydrates and iron.

In the end, the study confirms what we already know: The way you eat (and train; see Leon. 2001) can directly affect the level of the heart-healthy HDL fractions in your blood.

One thing you should keep in mind, though, is that it's the ln = logarithmus of these macronutrients and micronutrients that's associated with increased / decreased HDL and its subfractions. This means that small changes are not really important. Things that would count are eating low carb vs. extreme high carb or eating no folate containing foods vs. a significant amount of these.
  • Arts, Elke, et al. "High-density lipoprotein cholesterol subfractions HDL2 and HDL3 are reduced in women with rheumatoid arthritis and may augment the cardiovascular risk of women with RA: a cross-sectional study." Arthritis Res Ther 14.3 (2012): R116.
  • Buring, J. E., et al. "Decreased HDL2 and HDL3 cholesterol, Apo AI and Apo A-II, and increased risk of myocardial infarction." Circulation 85.1 (1992): 22-29.
  • Couvreur, S., et al. "The linear relationship between the proportion of fresh grass in the cow diet, milk fatty acid composition, and butter properties." Journal of dairy science 89.6 (2006): 1956-1969.
  • Dias, C. B., et al. "Saturated fat consumption may not be the main cause of increased blood lipid levels." Medical hypotheses 82.2 (2014): 187-195.
  • Gaziano, J. Michael, et al. "Moderate alcohol intake, increased levels of high-density lipoprotein and its subfractions, and decreased risk of myocardial infarction." New England Journal of Medicine 329.25 (1993): 1829-1834. 
  • Kim et al. "Effects of dietary components on high-density lipoprotein measures in a cohort of 1,566 participants." Nutrition & Metabolism 2014, 11:44.
  • Leon, ARTHUR S., and OTTO A. Sanchez. "Response of blood lipids to exercise training alone or combined with dietary intervention." Medicine and science in sports and exercise 33.6 Suppl (2001): S502-15.
  • Salonen, Jukka T., et al. "HDL, HDL2, and HDL3 subfractions, and the risk of acute myocardial infarction. A prospective population study in eastern Finnish men." Circulation 84.1 (1991): 129-139. 
  • Sodamade, A¹, and O. S. Bolaji. "Fatty acids composition of three different vegetable oils (soybean oil, groundnut oil and coconut oil) by high-performance liquid chromatography." Chemistry and Materials Research 3.7 (2013): 26-29.
  • Stampfer, Meir J., et al. "A prospective study of cholesterol, apolipoproteins, and the risk of myocardial infarction." New England Journal of Medicine 325.6 (1991): 373-381.