A randomized controlled trial studied the effects of low-carbohydrate diets with either low or high saturated fat content on cardiovascular risk factors in 40 healthy men. The men were randomly assigned to follow either a low-carbohydrate diet with beef as the main protein source and low saturated fat or the same diet with high saturated fat for 3 weeks, separated by a 2-week washout period. Compared to the high saturated fat diet, the low saturated fat diet improved cardiovascular risk markers like LDL cholesterol, HDL cholesterol, and LDL particle size. Replacing carbohydrates with beef and high saturated fat as part of a low-carbohydrate diet did not provide benefits and may have deleterious health effects.

1. Mangravite et al. Changes in
atherogenic dyslipidemia induced by
carbohydrate restriction in men are
dependent on dietary protein
source.
J Nutr. 2011 Dec;141(12):2180-5
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Dec;141(12):2180-5
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2. Page 2
Pronutritionist’s background
• In recent meta-analyses only marginal worsening of LDL cholesterol is
found, if anything during low carbohydrate high fat diet. On the other
hand, HDL cholesterolol, triglyserides and some measures of
carbohydrate metabolism may be improved (Kirk et al. 2008)
• In some previous short term studies, it’s been shown that low
carbohydrate high saturated fat diets will increase LDL levels but
improve holistic metabolic profiles in weight stable situation when diets
include mixed protein sources and saturated fat mainly comes from
dairy (Krauss et al. 2006)
• Red and especially processed meat has been linked to higher
cardiovascular risk in recent meta-analysis of prospective studies (
Micha&Mozaffarian 2009)
• The effect of low carbohydrate diet when carbohydrates are replaced
almost solely by red meat (beef) and high saturated fat intake is not
known.
• In Finland, red meat consumption is heavily promoted by many low carb
diet advocates
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3. Methods (patients)
• Randomized trial, cross over
• Primary outcomes: Changes in cardiovascular risk profile, such as
LDL-, HDL-cholesterol, triglyserides, size of lipoprotein particles
• Secondary outcomes: postprandial TG, glucose and insulin after fat
challenge
• N=40, healthy males (BMI 20-34)
• Length: 3 weeks per arm, 2 week wash out
• Run in (“baseline diet”): 2 weeks
– Carbohydrates 50 E %, Protein 13 E %, Fat 38 E %
– SFA 15 E %, PUFA 6 E %, MUFA 15 E %
– Beef protein 0 E %
• Experimental diets: Beef+ low SFA vs beef+ high SFA during restricted
intake of carbohydrates (no intend to lose weight)
• Entrees, lunch and dinner meals provided
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4. Methods (schematic)
Randomization
Beef + high SFA version
of low carb diet
Beef + low SFA version of
low carb diet
Beef + high SFA version of
low carb diet
Beef + low SFA version of
low carb diet
Wash out
2 weeks3 weeks 3
weeks
No beef, mixed other protein sources, high carbohydrate diet (50 % E), SFA
intake 15 % E
Run in diet
(2 weeks)
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5. Results (diet)
Low SFA + Beef
(low carb diet)
High SFA +Beef
(low carb diet)
Total fat 38 E % 38 E %
Carbohydrates 31 E % 31 E %
Protein 32 E % 31 E %
SFA 8 E % 15 E%
PUFA 6 E % 5 E %
MUFA 21 E % 15 E %
Dietary intakes (as provided)
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6. Results (lipids)
Run in (SFA 15
E %, High Carb)
Low SFA +
Beef
(low carb diet)
High SFA
+Beef
(low carb diet)
TG, mmol/l 1,22 1,0 1,1
LDL, mmol/l 2,87 2,5* 2,86
HDL, mmol/l 1,08 1,04* 1,07
Small LDL, nmol/l 207 187* 222
Medium LDL, “ 284 214* 304
Large LDL, “ 698 655 712
ApoB, g/l 0,74 0,68* 0,73
Fasting values (only statistical differences between low and high
beef diet given in this table, see the full paper for details)
*) p<0,05 low vs high SFA beef diets
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7. Results (postprandial 49 g fat
challenge as milkshake)
• Plasma TG and apoB48 increased after fat load during all
diets, and continued to increase throigh 6 hour period
• At 6 h time point, baseline diet (run-in) provided higher TG
values than either of two diets
• TG iAUC was reduced following intake of low SFA vs high
SFA period
• Glucose iAUC was reduced following both LC diets vs
baseline
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8. Pronutritionist’s discussion
• This was a weight stable study design, thus providing valuable
information on weight independent situation
• Authors state: “… reductions in the other lipoprotein-related risk factors,
including apoB and small LDL, were greatest following consumption of a
LCLSF diet” (Low Carbohydrate Low Saturated Fat)
• High SFA-high beef-low carbohydrate diet did not deliver any significant
benefit in cardiovascular risk markers when compared to high
carbohydrate diet (run-in), apart from reduced triglycerides
• In matter of fact, beef based high SFA low carbohydrate diet may have
have deleterious health effects both in terms of LDL concentration and
LDL particle size
• Taken together the present and previous randomized observations, red
and processed meat based high-saturated-fat LC diets seem to be a bad
idea, as many prospective cohort studies have suggested
• High saturated fat low carbohydrate diet does not improve LDL particle
profile when main protein source is beef
• This is a study by Ronald Krauss et co
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9. Please read the whole paper at
J Nutr. 2011
Dec;141(12):2180-5
http://twitter.com/pronutritionist
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24/09/13
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Reijo Laatikainen, Authorized Nutritionist, MBA
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