top of page

LOW CARB HEART HEALTH

This section outlines some of the key research findings regarding the effect of low carb diets and various heart-related health parameters.

​

 

KEY RESEARCH FINDINGS

There are conflicting results and arguments in the research regarding whether low carb diets are safe or unsafe for heart health. The research for each viewpoint is organized separately here.

 

FINDINGS THAT INDICATE THAT LOW CARB DIETS ARE SAFE

Low carb diets have been associated with a number of improvements in heart-related health markers including:

a. Reduced triglyceride

b. Increased high-density lipoprotein cholesterol (HDL)

c. A smaller proportion of small, dense low-density lipoprotein cholesterol (LDL) compared to larger, buoyant LDL

 

d. No association has been reported between saturated fat intake and all-cause mortality

e. High carb diets have associated with increased plasma triacylglycerol and decrease plasma HDL cholesterol concentrations

 

Perhaps somewhat surprisingly, low carb diets have been associated with a number of physiological markers that indicate enhanced heart-related health and well-being (a,b & c). Also, several studies report no association between saturated fat intake (which may increase in a low-carb diet) and all-cause mortality. Furthermore, high carb diets have been associated with physiological indicators of increased heart-related health risk (e). The indication is that reducing carb intake is better for heart health.

 

 

FINDINGS THAT INDICATE THAT LOW CARB DIETS ARE UNSAFE

f. High carb diets have been associated with reduced cardiac events in patients with heart disease

g. Dietary fibre has been associated with reduced rates of coronary heart disease

h. Increased dietary fat intake has been associated with an increased risk of heart-related health problems.

 

High carb diets have been associated with a number of improvements in heart-related health markers including:

i. reduced total cholesterol

j. reduced LDL

k. reduced triglycerides

 

l. Low carb diets have associated with changes associated with increased an increase or no reduction in LDL

 

The research that supports the safety of low-carb diets regarding heart health presented here shows improved physiological markers of heart health. However, long-term studies report an actual reduction in cardiac events in patients who adopt a high carb diet (f). Additionally, dietary fibre (a form of carbohydrate) intake is associated with a reduced rate of coronary heart disease (g). Furthermore, increased dietary fat intake (which is likely given a reduction in carbohydrate intake) has also been associated with an increased risk of heart-related health problems in long-term studies (h).

 

Finally, like low carb diets, high carb diets have also been associated with physiological indicators of enhanced heart-health (i,j & k), while low carb diets are associated with a number of indicators of heat-related health risk (l). 

​

PRACTICAL IMPLICATION: There are conflicting findings regarding the safety of low carb diets.

 

REFERENCES

SAFE

Low carb diets have been associated with

a. Low carb diets have been associated with reduced triglyceride

  • Hussain TA, Mathew Tc, Dashti AA, Asfar S, Al-Zaid N, et al. (2012) Effect of low-calorie versus low-carbohydrate ketogenic diet in type 2 diabetes. Nutrition 28: 1016-1021. 

  • Brinkworth GD, Noakes M, Buckley JD, et al. Long-term effects of a very-low-carbohydrate weight loss diet compared with an isocaloric low-fat diet after 12 mo. Am J Clin Nutr 2009;90:23–32.

  • Samaha FF, Iqbal N, Seshadri P, Chicano KL, Daily DA, et al. (2003) A low-carbohydrate as compared with a low-fat diet in severe obesity. N Engl J Med 348: 2074-2081.

  • Santos FL, Esteves SS, Da Costa PA, et al. Systematic review and meta-analysis of
    clinical trials of the effects of low carbohydrate diets on cardiovascular risk factors.
    Obes Rev 2012;13:1048–66. 

  • Hu T, Mills KT, Yao L, et al. Effects of low-carbohydrate diets versus low-fat diets
    on metabolic risk factors: a meta-analysis of randomized controlled clinical trials.
    Am J Epidemiol 2012;176(Suppl 7):S44–54. 

  • Volek JS, Phinney SD, Forsythe CE, et al. Carbohydrate restriction has a more favorable impact on the metabolic syndrome than a low fat diet. Lipids 2009;44:297–309. 

  • Foster GD, Wyatt HR, Hill JO, et al. A randomized trial of a low-carbohydrate diet for obesity. N Engl J Med 2003;348:2082–90.

  • Tay J, Brinkworth GD, Noakes M, et al. Metabolic effects of weight loss on a very-low-carbohydrate diet compared with an isocaloric high-carbohydrate diet in abdominally obese subjects. J Am Coll Cardiol 2008;51:59–67. 

  • Keogh JB, Brinkworth GD, Noakes M, et al. Effects of weight loss from a very- low-carbohydrate diet on endothelial function and markers of cardiovascular disease risk in subjects with abdominal obesity. Am J Clin Nutr 2008;87:567–76. 

  • Gardner CD, Kiazand A, Alhassan S, et al. Comparison of the Atkins, Zone, Ornish, and LEARN diets for change in weight and related risk factors among overweight premenopausal women: the A to Z Weight Loss Study: a randomized trial. JAMA 2007;297:969–77. (check)

  • Hession M, Rolland C, Kulkarni U, et al: Systematic review of randomized controlled trials of low-carbohydrate vs. low-fat/low-calorie diets in the management of obesity and its comorbidities. Obes Rev 2009; 10: 36–50.

 

b. Low carb diets have been associated with increased high density lipoprotein cholestrol (HDL)

  • Brehm BJ, Seeley RJ, Daniels SR, et al. (2003) A randomized trial comparing a very low carbohydrate diet and a calorie-restricted low fat diet on body weight and cardiovascular risk factors in healthy women. J Clin Endocrinol Metab 88, 1617–1623. 

  • Bueno NB, de Melo IS, de Oliveira SL, et al. (2013) Very- low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials. Br J Nutr 110, 1178–1187. 

  • Hussain TA, Mathew Tc, Dashti AA, Asfar S, Al-Zaid N, et al. (2012) Effect of low-calorie versus low-carbohydrate ketogenic diet in type 2 diabetes. Nutrition 28: 1016-1021. (not necessarily compared to LF)

  • Westman EC, Yancy WS Jr, Mavropoulos JC, et al. The effect of a low-carbohydrate, ketogenic diet versus a low-glycemic index diet on glycemic control in type 2 diabetes mellitus. Nutr Metab (Lond) 2008;5:36. 

  • Gardner CD, Kiazand A, Alhassan S, et al. Comparison of the Atkins, Zone, Ornish, and LEARN diets for change in weight and related risk factors among overweight premenopausal women: the A to Z Weight Loss Study: a randomized trial. JAMA 2007;297:969–77. 

  • Mensink RP, Zock PL, Kester AD, Katan MB: Effects ofdietary fatty acids and carbohydrates on the ratio of serumtotal to HDL cholesterol and on serum lipids and apolipoproteins: a meta-analysis of 60 controlled trials. Am J Clin Nutr2003, 77:1146–1155. 

  • Bazzano LA, Hu T, Reynolds K, et al. Effects of low-carbohydrate and low-fat
    diets: a randomized trial. Ann Intern Med 2014;161:309–18. 

  • Yancy WS Jr, Olsen MK, Guyton JR, et al. A low-carbohydrate, ketogenic diet versus a low-fat diet to treat obesity and hyperlipidemia: a randomized, controlled trial. Ann Intern Med 2004;140:769–77. 

  • Tay J, Brinkworth GD, Noakes M, et al. Metabolic effects of weight loss on a very-low-carbohydrate diet compared with an isocaloric high-carbohydrate diet in abdominally obese subjects. J Am Coll Cardiol 2008;51:59–67. 

  • Volek JS, Phinney SD, Forsythe CE, et al.: Carbohydrate restriction has a more favorable impact on the metabolic syndrome than a low fat diet. Lipids 2009, 44:297–309. 

  • Feinman RD, Volek JS, Westman EC. Dietary carbohydrate restriction in the treatment of diabetes and metabolic syndrome. Clin Nutr Insight 2008;34:5. 

  • Shai I, Schwarzfuchs D, Henkin Y, et al. Weight loss with a low-carbohydrate, Mediterranean, or low-fat diet. N Engl J Med 2008;359:229–41.

 

c. Low carb diets have been associated with a smaller proportion of small, dense LDL compared to larger, buoyant LDL

  • Volek JS, Phinney SD, Forsythe CE, et al. Carbohydrate restriction has a more favorable impact on the metabolic syndrome than a low fat diet. Lipids 2009;44:297–309. 

  • Aude YW, Agatston AS, Lopez-Jimenez F, et al. The national cholesterol education program diet vs a diet lower in carbohydrates and higher in protein and monounsaturated fat: a randomized trial. Arch Intern Med 2004;164:2141–6. 

  • Volek JS, Fernandez ML, Feinman RD, et al. Dietary carbohydrate restriction induces a unique metabolic state positively affecting atherogenic dyslipidemia, fatty acid partitioning, and metabolic syndrome. Prog Lipid Res 2008;47:307–18. 

  • Forsythe CE, Phinney SD, Feinman RD, et al. Limited effect of dietary saturated fat on plasma saturated fat in the context of a low carbohydrate diet. Lipids 2010;45:947–62. 

  • Wood RJ, Volek JS, Liu Y, et al. Carbohydrate restriction alters lipoprotein metabolism by modifying VLDL, LDL, and HDL subfraction distribution and size in overweight men. J Nutr 2006;136:384–9. 

  • Volek JS, Sharman MJ, Forsythe CE. Modification of lipoproteins by very low-carbohydrate diets. J Nutr 2005;135:1339–42.

 

d. No association has been reported between saturated fat intake and all-cause mortality

  • Siri-Tarino PW, Sun Q, Hu FB, et al. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. Am J Clin Nutr 2010;91:535–46. 

  • Hooper L, Summerbell CD, Thompson R, et al. Reduced or modified dietary fat for preventing cardiovascular disease. Cochrane Database Syst Rev 2012;(5):CD002137. 

  • Hooper L, Summerbell CD, Thompson R, et al. Reduced or modified dietary fat for preventing cardiovascular disease. Cochrane Database Syst Rev 2011;(7): CD002137. 

  • Skeaff CM, Miller J. Dietary fat and coronary heart disease: summary of evidence from prospective cohort and randomised controlled trials. Ann Nutr Metab 2009;55:173–201. 

  • Jakobsen MU, O’Reilly EJ, Heitmann BL, et al. Major types of dietary fat and risk of coronary heart disease: a pooled analysis of 11 cohort studies. Am J Clin Nutr 2009;89:1425–32. 

  • De Souza RJ, Mente A, Maroleanu A, et al. Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies. BMJ 2015;351:h3978. 

  • Praagman J, Beulens JW, Alssema M, et al. The association between dietary saturated fatty acids and ischemic heart disease depends on the type and source of fatty acid in the European

  • Prospective Investigation into Cancer and Nutrition-Netherlands cohort. Am J Clin Nutr 2016;103:356–65. 

  • Mente A, De Koning L, Shannon HS, et al. A systematic review of the evidence
    supporting a causal link between dietary factors and coronary heart disease. Arch
    Intern Med 2009;169:659–69. 

  • Chowdhury R, Warnakula S, Kunutsor S, et al. Association of dietary, circulating,
    and supplement fatty acids with coronary risk: a systematic review and
    meta-analysis. Ann Intern Med 2014;160:398–406. 

  • Puaschitz NG, Strand E, Norekval TM, et al. Dietary intake of saturated fat is not
    associated with risk of coronary events or mortality in patients with established
    coronary artery disease. J Nutr 2015;145:299–305. 

  • Schoenaker DA, Toeller M, Chaturvedi N, et al. Dietary saturated fat and fibre and
    risk of cardiovascular disease and all-cause mortality among type 1 diabetic patients: the EURODIAB Prospective Complications Study. Diabetologia 2012;55:2132–41.

 

e. High carb diets have associated with increased plasma triacylglycerol and decrease plasma HDL cholesterol concentrations

  • Borkman M, Campbell LV, Chisholm DJ, Storlien LH. 1991. Comparison of the effects on insulin sensitivity of high carbohydrate and high-fat diets in normal subjects. J Clin Endocrinol Metab 72:432–437. 

  • Brussaard JH, Katan MB, Groot PHE, Havekes LM, Hautvast JGAJ. 1982. Serum lipoproteins of healthy persons fed a low-fat diet or a polyunsaturated fat diet for three months. A comparison of two cholesterol-lowering diets. Atherosclerosis 42:205–219.

  • Marckmann P, Raben A, Astrup A. 2000. Ad libitum intake of low-fat diets rich in either starchy foods or sucrose: Effects on blood lipids, factor VII coagulant activity, and fibrinogen. Metabolism 49:731–735.

  • West CE, Sullivan DR, Katan MB, Halferkamps IL, van der Torre HW. 1990. Boys from populations with high-carbohydrate intake have higher fasting tri- glyceride levels than boys from populations with high-fat intake. Am J Epidemiol 131:271–282. 

  • Yost TJ, Jensen DR, Haugen BR, Eckel RH. 1998. Effect of dietary macronutrient composition on tissue-specific lipoprotein lipase activity and insulin action in normal-weight subjects. Am J Clin Nutr 68:296–302. 

 

 

UNSAFE

f. High carb diets have been associated with reduced less cardiac events in patients with heart disease

  • Intensive Lifestyle Changes for Reversal of Coronary Heart Disease  Ornish D, Scherwitz LW, Billings JH, et al. JAMA. 1998;280(23):2001-7. 

 

g. Dietary fibre has been associated with reduced rates of coronary heart disease

  • Jacobs DR, Meyer KA, Kushi LH, Folsom AR. 1998. Whole-grain intake may reduce the risk of ischemic heart disease death in postmenopausal women: The Iowa Women’s Health Study. Am J Clin Nutr 68:248–257. 

  • Kushi LH, Lew RA, Stare FJ, Ellison CR, el Lozy M, Bourke G, Daly L, Graham I, Hickey N, Mulcahy R, Kevaney J. 1985. Diet and 20-year mortality from coronary heart disease. The Ireland-Boston Diet-Heart Study. N Engl J Med 312:811– 818. 

  • Pietinen P, Rimm EB, Korhonen P, Hartman AM, Willett WC, Albanes D, Virtamo J. 1996. Intake of dietary fiber and risk of coronary heart disease in a cohort of Finnish men. The Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. Circulation 94:2720–2

 

 

h. Increased dietary fat intake has been associated with an increased risk of heart-related health problems

  • Hooper L, Martin N, Abdelhamid A,et al. Reduction in saturated fat intake for cardiovascular disease. Cochrane Database Syst Rev 2015: CD011737. 

  • de Oliveira Otto MC, Mozaffarian D, Kromhout D, et al. Dietary intake of saturated fat by food source and incident cardiovascular disease: the Multi-Ethnic Study of Atherosclerosis. Am J Clin Nutr 2012; 96: 397–404.

 

i. High carb diets have been associated with reduced total cholesterol

  • The Effectiveness and Efficacy of an Intensive Cardiac Rehabilitation Program in 24 Sites Silberman, A, Banthia, R, Estay I, Kemp, C, Studley, J, Hareras, D, Ornish, D American Journal of Health Promotion. 2010;4:260-266. 

  • The Contribution of Changes in Diet, Exercise, and Stress Management to Changes in Coronary Risk in Women and Men in the Multisite Cardiac Lifestyle Intervention Program Daubenmier, J, Weidner, G, Sumner, M, Mendell, N, Merritt-Worden, T, Studley, J, Ornish, D. Annuals of Behavioral Medicine. 2007;33(1):57-68.

  • Lifestyle Changes and Clinical Profile in Coronary Heart Disease Patients with an Ejection Fraction of ≤40% or >40% in the Multicenter Lifestyle Demonstration Pischke, C, Weidner, G, Elliott-Eller, M, Ornish, D. European Journal of Heart Failure. 2007:928-934. 

  • Marked Improvements in Biomedical and Psychosocial Cardiac Risk Factors From a Community-Based Lifestyle Change Program Merritt-Worden T, Ornish D, Pettengill E. Circulation. 2003;17:IV-758. 

  • Community-Based Lifestyle Change Program Produces Substantial Reductions in Biomedical and Psychosocial Cardiac  Risk Factors  Pettengill E, Pearson J, Pifalo B, et al. Circulation. 2002;106:76e-123. 

  • Effects of Intensive Lifestyle Changes on Coronary Heart Disease Risk Factors and Clinical Status in Self-Selected Heart Patients Merritt, T, Ornish, D, Scherwitz, L, et al. JCR. 1995;15:353. 

 

j. High carb diets have been associated with reduced LDL

  • The Effectiveness and Efficacy of an Intensive Cardiac Rehabilitation Program in 24 Sites Silberman, A, Banthia, R, Estay I, Kemp, C, Studley, J, Hareras, D, Ornish, D American Journal of Health Promotion. 2010;4:260-266. 

  • Weight loss / reduced BMI Socioeconomic Status and Improvements in Lifestyle, Coronary Risk Factors, and Quality of Life: The Multisite Cardiac Lifestyle Intervention Program Govil, S, Weidner, G, Merritt-Worden, T, Ornish, D. American Journal Public Health. 2009;99:1263-1270. 

  • The Contribution of Changes in Diet, Exercise, and Stress Management to Changes in Coronary Risk in Women and Men in the Multisite Cardiac Lifestyle Intervention Program Daubenmier, J, Weidner, G, Sumner, M, Mendell, N, Merritt-Worden, T, Studley, J, Ornish, D. Annuals of Behavioral Medicine. 2007;33(1):57-68.

  • Lifestyle Changes and Clinical Profile in Coronary Heart Disease Patients with an Ejection Fraction of ≤40% or >40% in the Multicenter Lifestyle Demonstration Pischke, C, Weidner, G, Elliott-Eller, M, Ornish, D. European Journal of Heart Failure. 2007:928-934. 

  • Comparison of Coronary Risk Factors and Quality of Life in Coronary Artery Disease Patients With Versus Without Diabetes Mellitus Pischke, C, Weidner, G, Elliott-Eller, M, Scherwitz, L, Merritt-Worden, T, Marlin, R, Lipsenthal, L, Finkel, R, Saunders, D, McCormac, P, Scheer, J, Collins, R, Guarneri, E, Ornish, D. American Journal of Cardiology. 2006;97:1267-1273. 

  • Effects of Intensive Lifestyle Changes on Coronary Heart Disease Risk Factors and Clinical Status in Self-Selected Heart Patients Merritt, T, Ornish, D, Scherwitz, L, et al. JCR. 1995;15:353. 

​

k. High carb diets have been associated with reduced triglycerides

  • The Effectiveness and Efficacy of an Intensive Cardiac Rehabilitation Program in 24 Sites Silberman, A, Banthia, R, Estay I, Kemp, C, Studley, J, Hareras, D, Ornish, D American Journal of Health Promotion. 2010;4:260-266. 

  • Comparison of Coronary Risk Factors and Quality of Life in Coronary Artery Disease Patients With Versus Without Diabetes Mellitus Pischke, C, Weidner, G, Elliott-Eller, M, Scherwitz, L, Merritt-Worden, T, Marlin, R, Lipsenthal, L, Finkel, R, Saunders, D, McCormac, P, Scheer, J, Collins, R, Guarneri, E, Ornish, D. American Journal of Cardiology. 2006;97:1267-1273. 

  • Marked Improvements in Biomedical and Psychosocial Cardiac Risk Factors From a Community-Based Lifestyle Change Program Merritt-Worden T, Ornish D, Pettengill E. Circulation. 2003;17:IV-758. 

  • Community-Based Lifestyle Change Program Produces Substantial Reductions in Biomedical and Psychosocial Cardiac  Risk Factors  Pettengill E, Pearson J, Pifalo B, et al. Circulation. 2002;106:76e-123. 

 

 

l. Low carb diets have associated with changes associated with increased an increase or no reduction in LDL

  • Bueno NB, de Melo IS, de Oliveira SL, et al. (2013) Very- low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials. Br J Nutr 110, 1178–1187.

  • McAuley KA, Hopkins CM, Smith KJ, et al. (2005) Comparison of high-fat and high-protein diets with a high-carbohydrate diet in insulin-resistant obese women. Diabetologia 48, 8–16. 

  • Tay J, Brinkworth GD, Noakes M, et al. (2008) Metabolic effects of weight loss on a very-low-carbohydrate diet compared with an isocaloric high-carbohydrate diet in abdominally obese subjects. J Am Coll Cardiol 51, 59–67.

  • Nordmann AJ, Nordmann A, Briel M, et al. (2006) Effects of low- carbohydrate vs low-fat diets on weight loss and cardiovascular risk factors – a meta-analysis of randomized controlled trials. Arch Inter Med 166, 285–293. 

  • Schwingshackl L & Hoffmann G (2013) Comparison of effects of long-term low-fat vs high-fat diets on blood lipid levels in overweight or obese patients: a systematic review and meta-analysis. J Acad Nutr Diet 113, 1640–1661. 

  • Brinkworth GD, Noakes M, Buckley JD, et al. (2009) Long- term effects of a very-low-carbohydrate weight loss diet compared with an isocaloric low-fat diet after 12 mo. Am J Clin Nutr 90, 23–32.

  • Hernandez TL, Sutherland JP, Wolfe P, et al. Lack of suppression of circulating free fatty acids and hypercholesterolemia during weight loss on a high-fat, low-carbohydrate diet. Am J Clin Nutr 2010;91:578–85.

  • Tay J, Brinkworth GD, Noakes M, et al. Metabolic effects of weight loss on a very-low carbohydrate diet compared with an isocaloric high-carbohydrate diet in abdominally obese subjects. J Am Coll Cardiol 2008;51:59–67. 

  • lchf increase hdl, decrease tg and weight without any sig effect on ldl-c 14

  • Santos FL, Esteves SS, Da Costa PA, et al. Systematic review and meta-analysis of
    clinical trials of the effects of low carbohydrate diets on cardiovascular risk factors.
    Obes Rev 2012;13:1048–66.

 

 

FULL REVIEWS

  • Westman et al (2003) A review of low-carbohydrate ketogenic diets. Curr Atheroscler Rep. Nov;5(6):476-83.

  • Noakes TD, Windt J. Br J Sports Med 2016;51:133–139. Evidence that supports the prescription of low-carbohydrate high-fat diets: a narrative review

​

bottom of page