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title

Hypertriglyceridemia: 5 Abstracts
Am J Clin Nutr 2003 Jan;77(1):43-50
Hepatic de novo lipogenesis in normoinsulinemic and hyperinsulinemic subjects consuming high-fat, low-carbohydrate and low-fat, high- carbohydrate isoenergetic diets.
author
Schwarz JM, Linfoot P, Dare D, Aghajanian K.
Department of Nutritional Sciences and Toxicology, University of California, Berkeley (J-MS and KA), and the Department of Medicine, University of California, San Francisco (J-MS, PL, and DD).
abstract
BACKGROUND: Hypertriglyceridemia is associated with increased risk of cardiovascular disease. Until recently, the importance of hepatic de novo lipogenesis (DNL) in contributing to hypertriglyceridemia was difficult to assess because of methodologic limitations. OBJECTIVE: We evaluated the extent of the contribution by DNL to different conditions associated with hypertriglyceridemia. DESIGN: After 5 d of an isoenergetic high-fat, low-carbohydrate diet, fasting DNL was measured in normoinsulinemic (</= 85 pmol/L) lean (n = 9) and obese (n = 6) and hyperinsulinemic (>/= 115 pmol/L) obese (n = 8) subjects. Fasting DNL was measured after a low-fat, high- carbohydrate diet in normoinsulinemic lean (n = 5) and hyperinsulinemic obese (n = 5) subjects. Mass isotopomer distribution analysis was used to measure the fraction of newly synthesized fatty acids in VLDL-triacylglycerol. RESULTS: With the high-fat, low- carbohydrate diet, hyperinsulinemic obese subjects had a 3.7-5.3-fold higher fractional DNL (8.5 +/- 0.7%) than did normoinsulinemic lean (1.6 +/- 0.5%) or obese (2.3 +/- 0.3%) subjects. With the low-fat, high-carbohydrate diet, normoinsulinemic lean and hyperinsulinemic obese subjects had similarly high fractional DNL (13 +/- 5.1% and 12.8 +/- 1.4%, respectively). Compared with baseline, consumption of the high-fat, low- carbohydrate diet did not affect triacylglycerol concentrations. However, after the low-fat, high-carbohydrate diet, triacylglycerols increased significantly and DNL was 5-6-fold higher than in normoinsulinemic subjects consuming a high-fat diet. The increase in triacylglycerol after the low-fat, high-carbohydrate diet was correlated with fractional DNL (P < 0.01), indicating that subjects with high DNL had the greatest increase in triacylglycerols. CONCLUSIONS: These results support the concept that both hyperinsulinemia and a low-fat diet increase DNL, and that DNL contributes to hypertriglyceridemia.
index
PMID: 12499321 [PubMed - in process]
   
abstract2
Arterioscler Thromb Vasc Biol 2001 Sep;21(9):1520-5
Exercise prevents the accumulation of triglyceride-rich lipoproteins and their remnants seen when changing to a high-carbohydrate diet.
Koutsari C, Karpe F, Humphreys SM, Frayn KN, Hardman AE.
Human Muscle Metabolism Research Group, Loughborough University, Loughborough, UK.
We tested the hypothesis that daily aerobic exercise opposes the fasting hypertriglyceridemia and exaggerated postprandial lipemia observed after substituting dietary fat with carbohydrate. Eight healthy postmenopausal women aged 51 to 66 years consumed the same high-fat mixed meal on 3 occasions: (1) after 3 days on a low- carbohydrate diet (35%, 50%, and 15% energy from carbohydrate, fat, and protein, respectively); (2) after 3 days on an isoenergetic high-carbohydrate diet (corresponding values 70%, 15%, and 15%); and (3) after 3 days on the same high-carbohydrate diet with 60 minutes of brisk walking daily. Plasma triglycerides were higher after the high- carbohydrate diet than after the low-carbohydrate diet: fasting, 1.58+/-0.19 versus 0.96+/- 0.12 mmol/L, respectively; 6-hour postprandial area under concentration versus time curve, 13.74+/-1.57 versus 10.12+/-1.15 (mmol/L)xhour, respectively (both P<0.01). In the fasted and postprandial states, concentrations of apolipoproteins B-48 and B-100 in the triglyceride-rich lipoprotein fraction were significantly higher after the high- carbohydrate diet, as was the concentration of remnant-like lipoprotein particle cholesterol (a measure of lipoprotein remnants). These carbohydrate-induced increases in the number of circulating triglyceride-rich particles and their remnants were abolished when subjects had exercised daily during the high-carbohydrate diet.
PMID: 11557682 [PubMed - indexed for MEDLINE]
   
abstract3
J Am Coll Nutr 2000 Jun;19(3):383-91
Fasting lipoprotein and postprandial triacylglycerol responses to a low- carbohydrate diet supplemented with omega-3 fatty acids.
Volek JS, Gomez AL, Kraemer WJ.
The Human Performance Laboratory, Ball State University, Muncie, Indiana 47306, USA.
BACKGROUND: The effects of a prolonged low-carbohydrate diet rich in omega-3 fatty acids on blood lipid profiles have not been addressed in the scientific literature. OBJECTIVE: This study examined the effects of an eight-week ketogenic diet rich in omega-3 fatty acids on fasting serum lipoproteins and postprandial triacylglycerol (TG) responses. DESIGN: Ten men consumed a low-carbohydrate diet rich in monounsaturated fat (MUFA) and supplemented with omega-3 fatty acids for eight weeks. Fasting blood samples were collected before and after one week of habitual diet and on two consecutive days after 2, 4, 6 and 8 weeks of the intervention diet. Postprandial TG responses to a fat-rich test meal were measured prior to and after the intervention diet. RESULTS: Compared to the habitual diet, subjects consumed significantly (p < or = 0.05) greater quantities of protein, fat, MUFA and omega-3 fatty acids and significantly less total energy, carbohydrate and dietary fiber. Body weight significantly declined over the experimental period (-4.2+/-2.7 kg). Compared to baseline, fasting total cholesterol, LDL cholesterol and HDL cholesterol were not significantly different after the intervention diet (+1.5%, +9.7% and +10.0%, respectively). Fasting TG were significantly reduced after the intervention diet (-55%). There was a significant reduction in peak postprandial TG (-42%) and TG area under the curve (-48%) after the intervention diet. CONCLUSIONS: A hypocaloric low- carbohydrate diet rich in MUFA and supplemented with omega-3 fatty acids significantly reduced postabsorptive and postprandial TG in men that were not hypertriglyceridemic as a group before the diet. This may be viewed as a clinically significant positive adaptation in terms of cardiovascular risk status. However, transient increases in total cholesterol and LDL cholesterol were also evident and should be examined further in regard to which particular subfractions are elevated.
PMID: 10872901 [PubMed - indexed for MEDLINE]
   
abstract4

Am J Physiol 1987 Dec;253(6 Pt 1):E664-9
Effect of carbohydrate intake on de novo lipogenesis in human adipose tissue.
Chascione C, Elwyn DH, Davila M, Gil KM, Askanazi J, Kinney JM.
Department of Surgery, College of Physicians and Surgeons, Columbia University, New York, New York 10032.
Rates of synthesis, from [14C]glucose, of fatty acids (de novo lipogenesis) and glycerol (triglyceride synthesis) were measured in biopsies of adipose tissue from nutritionally depleted patients given low- or high-carbohydrate intravenous nutrition. Simultaneously, energy expenditure and whole-body lipogenesis were measured by indirect calorimetry. Rates of whole-body lipogenesis were zero on the low-carbohydrate diet and averaged 1.6 g.kg-1.day-1 on the high-carbohydrate diet. In vitro rates of triglyceride synthesis increased 3-fold going from the low to the high intake; rates of fatty acid synthesis increased approximately 80-fold. In vitro, lipogenesis accounted for less than 0.1% of triglyceride synthesis on the low intake and 4% on the high intake. On the high- carbohydrate intake, in vitro rates of triglyceride synthesis accounted for 61% of the rates of unidirectional triglyceride synthesis measured by indirect calorimetry. In vitro rates of lipogenesis accounted for 7% of whole-body lipogenesis. Discrepancies between in vitro rates of fatty acid synthesis from glucose, compared with acetate and citrate, as reported by others, suggest that in depleted patients on hypercaloric high-carbohydrate diets, adipose tissue may account for up to 40% of whole-body lipogenesis.
PMID: 3122584 [PubMed - indexed for MEDLINE]
   
abstract5
Versicherungsmedizin 1995 Aug 1;47(4):116-22
Comment in:
Versicherungsmedizin. 1995 Dec 1;47(6):231-3.
[Nutrition and coronary heart disease: how important is diet?]
[Article in German]
Worm N.
Three saturated fatty acids (C 12:0, C 14:0, C 16:0) raise LDL cholesterol but also HDL cholesterol levels. Replacement of these fatty acids by monounsaturated or omega-6 polyunsaturated fatty acids will lower LDL cholesterol as well as HDL cholesterol levels. Fat modified diets therefore may not improve the ratio of LDL to HDL cholesterol. Linoleic acid enhances sterol excretion but also increases cholesterol synthesis so that total body cholesterol is not diminished. Moreover various potentially adverse effects have been reported for omega-6 polyunsaturated fatty acids. Recent cross-cultural ecologic studies as well as all major within-population cohort studies have not been able to find an association between cholesterol raising saturated fatty acids of animal fat and risk of Coronary Heart Disease (CDH). On the other hand several cohort and case control studies have shown an increase in CHD risk with increasing consumption of partly hydrogenated vegetable margarines. Meta-analyses of controlled intervention studies reveal that cholesterol lowering diets have failed to lower risk of CHD or total mortality. Yet controlled studies implementing a high level of antioxidants in the diet or increasing the omega-3 unsaturated fatty acid content have been able to lower CHD and total mortality. It is time to discuss whether the concept of dietary intervention with the "classic" cholesterol lowering diet is still justified.
Publication Types:
Review
Review, Tutorial
PMID: 7676547 [PubMed - indexed for MEDLINE]
 

 
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