Effects of dietary carbohydrate restriction versus low-fat diet on flow-mediated dilation.
26
2009
Effects of dietary carbohydrate restriction versus low-fat diet on flow-mediated dilation. JS Volek, KD Ballard, R Silvestre et al. Metabolism Clinical and Experimental 2009;58:1769-1777.
US
1
To address concern about how carb-restricted diets affect vascular function because high-fat meals have acutely impaired endothelial function.
40
12%
45
12 weeks
N
40
"Aim of diet was to induce a low level of ketosis Targets E: ~1500kcal/d Carb: 12%E Protein: 28%E Fat: 59%E Intake E: 1504kcal/d Carb: 44.8g/d, 12.4%E Protein: 104.8g/d; 28.1%E Fat: 100.2g/d, 58.9%E (36.4g/d saturated fat)"
"Lowfat diet Subjects instructed on foods allowed and to avoid. Targets E: ~1500kcal/d Carb: ~55%E Protein: ~20%E Fat: ~24%E (10%E from saturated fat; <300mg cholestrol/d). Intake E: 1478kcal/d Carb: 208.3g/d, 55.8%E Protein: 71.5g/d; 19.6%E Fat: 40.0g/d, 23.8%E (11.7g/d saturated fat)"
"Primary: fasting and post-prandial vascular function Measures at 12 weeks, giving time for adaptation to a LC diet. Measures were taken hourly up to 6 hours after high-fat (84% fat) meal for flow mediated dilation, TG, insulin, non-esterfied fatty acides (NEFA), as well as measures of inflammation [leukocytes, neutrophils, lymphocytes, interleukin-6 (IL-6)]. "
There was no evidence that the LC diet caused endothelial dysfunction. The LC diet performed SS better than the LF diet on improving flow mediated dilation, TG and other markers for endothelial function.
NR
*
*
"Post-prandial lymphocytes WG: NR BG: Y LC diet: -12% LF diet: -1% BG SS p=0.05 Post-prandial interleukin-6 LC diet: +46% LF diet: -13% BG SS p=0.038"
*
*
NR
NR
"Peak-flow mediated dilation at 3 hours after meal WG: NR BG: Y Baseline→12 wks LC diet 5.1%→6.5% LF diet 7.9%→5.2% BG SS p=0.004"
"...subjects who adapted to a diet very low in carbohydrate showed no evidence of vascular dysfunction in response to a high-fat meal. The findings are consistent with our proposed theory that carbohydrate restriction uniquely benefits features of metabolic syndrome including endothelial function."
Abbreviations:
AHA - American Heart Association;
ALT - alanine aminotransferase;
AMDR - acceptable macronutrient distribution range;
AST - aspartate aminotransferase;
BG - between study groups;
BHOB - beta-hydroxybutyrate;
DBP - diastolic blood pressure;
E- energy, caloric intake;
eGFR - estimated glomerular filtration rate;
FBG - fasting blood glucose;
GGT - gamma-glutamyl transferase;
HDL-C - high-density lipoprotein cholesterol;
iGFR - isotope glomerurar filtration rate;
LDL-C - low-density lipoprotein cholesterol;
NAFLD - non-alcoholic fatty liver disease;
NR - not reported (or data needed for calculation not available);
N - no;
NA - not applicable;
NS - not specified;
NSS - not statistically significant;
SBP - systolic blood pressure;
SS - statistically significant;
TG - triglyceride;
total C - total cholesterol;
V - varied, mixed;
WG - within a study group;
WMD - weighted mean difference;
Y - yes
Number of People in Studies:
3,296 Enrolled in randomized controlled trials on 25% or less carbohydrates
2,626 Completed randomized controlled trials on 25% or less carbohydrates
79.67% 82% completion of studies
Duration of Trial
<6 Months
6-9 Months
1 -2 years
>2 years
# of Trials
36
6
9s
1