Re: de novo synthesis of Fats from Carbohydrates

[Guest guest]

Tony

I had a look at that link and it's PDF file. As you know I am very

interested in the effect of carbohydrate intake on my cholesterol.

However I couldn't understand very much of it. I know one or two

people 'lurk' here, interested, but like me, sometimes find the

science gets a bit heavy going so I'm posting a request rather than

emailing off-line.

Would you mind summarising this for me, briefly

Thanks, Gay

--- In , " citpeks " <citpeks@y...>

wrote:

> One of the interesting questions about macronutrient balance is:

how

> much saturated fat is created from carbohydrates in the diet?

>

> Here is an article that gives us a good idea:

>

> http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=507644

>

> J Clin Invest. 1996 November 1; 98(9): 2008–2017.

>

> Contributions of de novo synthesis of fatty acids to total

> VLDL-triglyceride secretion during prolonged

> hyperglycemia/hyperinsulinemia in normal man.

>

> A Aarsland, D Chinkes, and R R Wolfe

> Metabolism Unit, Shriners Burns Institute and University of Texas

> Medical Branch, Galveston 77550, USA.

>

> Triglycerides (TG) are synthesized in the liver principally from

two

> sources of fatty acids (FA): FA synthesized de novo in the liver

and

> preformed FA. We have measured the rate of secretion of de novo

> synthesized FA and total secretion of FA bound to VLDL-TG in

healthy

> men (n = 5) in the basal state, and after 1 (day 1) and 4 d (day

4) of

> a hypercaloric carbohydrate diet (approximately 2.5 times energy

> expenditure) that generated a moderate endogenous hyperinsulinemia

> (plasma insulin approximately 60 microU/ml). Prolonged carbohydrate

> hyperalimentation/hyperinsulinemia increased plasma VLDL-TG

> approximately 10-fold in part due to a 3.4-fold increase in total

> VLDL-TG secretion rate (basal state = 72+/-23, day 4 = 242+/-78

> micromol TG/kg/d). Although the secretion of de novo synthesized FA

> increased throughout the study (basal state = 1.1+/-0.4, day 1 =

> 15.9+/-7.9, day 4 = 50.0+/-18.8 micromol TG/ kg/d), the 2.7-fold

> increase in secretion rate of preformed FA (basal state = 70+/-23,

day

> 4 = 191+/-57 micromol TG/kg/d) quantitatively contributed the most

to

> total VLDL-TG secretion rate. Decreased catabolism of VLDL-TG also

> contributed to the hypertriglyceridemia as reflected by an

> approximately fourfold decrease in both fractional turnover rate

> (basal state = 9.2+/-3.8, day 1 = 2.1+/-0.2, day 4 = 2.1+/-0.3

> pools/d) and rate of clearance (basal state = 0.35+/-0.08, day 1 =

> 0.11+/-0.01, day 4 = 0.09+/-0.01 liter/kg/d) of VLDL-TG. Thus, the

> primary difference between 1 and 4 d of hyperinsulinemia in

> conjunction with carbohydrate hyperalimentation is the increase in

> hepatic secretion of preformed FA into VLDL-TG.

>

>

> Tony