Published: 02/08/2024

Heart Health: How a Low-Carb Lifestyle Impacts Cardiovascular Disease Risk

When a diet calls for cutting down on carbohydrates, the balance of macronutrients shifts to place a greater reliance on fat for energy. So, can a low-carb diet, that is higher in fat, help reduce cardiovascular disease (CVD) risk? The answer may surprise you and your patients.  

More Fat and Fewer Carbs: A Recipe for Heart Health 

Fat is a broad category of macronutrients, with each type having a different effect on the body. Contrary to popular belief, fats are not the enemy of a diet plan and should not be feared among those trying to lose weight.  

For example, the Mediterranean diet, long considered the gold standard for heart health, is not a low-fat diet. 1 Eating the Mediterranean way includes consuming nutrient-dense fat sources, such as olive oil, fatty fish and nuts. The PREDIMED study, a major study on diet and CVD risk, found that participants following the Mediterranean diets plus additional fats of either nuts or olive oil (38-41% of total calories from fat) had a lower risk of cardiovascular events in the five years following their intervention than those on the low-fat diet.2   

As for low carbohydrate diets in general, randomized clinical trials have also found that low-carbohydrate diets are more effective than low-fat diets in reducing cardiovascular risk factors and for helping with weight loss.3, 4 

Saturated Fats Are OK, Too 

While saturated fats have been long regarding as “bad,” emerging research suggests some saturated odd-chain fatty acids (those with an odd number of carbon atoms in the backbone) found in full-fat and fermented dairy, such as pentadecanoic acid (15:0) are associated with reduced adiposity and CVD.5,6 

We know that oils, nuts and other unsaturated fats tend to be more heart-healthy, but not all saturated fats should be avoided. A systematic review and meta-analysis found that saturated fats such as stearic  acid, the primary saturated fatty acid in dark chocolate, unprocessed meat, as well as in dairy products, have a neutral effect or can even reduce CVD risk.7 

Dietary Fats and Blood Lipids  

In addition, fats consumed in the diet influence blood lipids, which may in turn,  affect CVD risk. Lipoproteins are spherical particles that carry fats/lipids, such as cholesterol and triglycerides, in the body. Low-density lipoprotein (LDL) levels, as well as the ratio between total cholesterol to high-density lipoproteins (HDL) levels, are considered markers for CVD risk 8  

The old school of thought is that LDL-cholesterol and cardiovascular disease risk have a direct relationship – the higher the LDL levels, the greater the risk.8 With this said, the science in this areas is evolving – studies have found that following the Mediterranean eating pattern may indeed reduce CVD risk,9 including reducing levels of oxidized LDL,10 but without a significant change in overall LDL levels.Rather, the type of LDL may have a greater impact on CVD risk, with small, dense LDL particles appearing to be more atherogenic than large, fluffy LDL – because they can be more easily oxidized.11  

Counseling Patients on Heart Healthy, Lower Carb Eating Patterns 

Staying up to date on the latest science of fats and on cardio-protective dietary patterns is important for health care professionals, as diet and lifestyle choices are modifiable risk factors for CVD. Here are a few tips to help your patients reduce their risk and create heart-healthy habits: 

  • Consider a low-carb diet that follows a Mediterranean-style eating pattern. That is, one that includes fish, lean meats, oils, legumes and fresh produce. (Try this meal plan that incorporates the Atkins approach within the Mediterranean diet.)
  • Choose unsaturated fats (oils, nuts, fish, avocados) when convenient, but don’t be afraid of incorporating saturated fats within reason. Fats in the diet help with absorption of fat-soluble vitamins.12 For example, using salad dressings that contain fat can be more beneficial to your patient than fat-free options.
  • Consider the food matrix and other nutrients within a food that can be beneficial for health. Nutrient-dense foods such as dairy not only provide beneficial fats, but also calcium, vitamin D and other essential nutrients that support heart health.  

References:

1. https://www.hsph.harvard.edu/nutritionsource/healthy-weight/diet-reviews/mediterranean-diet/. 

2. Estruch R, Ros E, Salas-Salvadó J, et al. Primary prevention of cardiovascular disease with a mediterranean diet supplemented with extra-virgin olive oil or nuts. N Engl J Med. 2018 378:e34. DOI: 10.1056/NEJMoa1800389 [Note: reference updated in June 2018 due to retraction and republication]. 

3. Bazzano LA, Hu T, Reynolds K, Yao L, Bunol C, Liu Y, Chen CS, Klag MJ, Whelton PK, He J. Effects of low-carbohydrate and low-fat diets: a randomized trial. Ann Intern Med. 2014 Sep 2;161(5):309-18. doi: 10.7326/M14-0180. PMID: 25178568; PMCID: PMC4428290. 

4. Sackner-Bernstein J, Kanter D, Kaul S. Dietary Intervention for Overweight and Obese Adults: Comparison of Low-Carbohydrate and Low-Fat Diets. A Meta-Analysis. PLoS One. 2015 Oct 20;10(10):e0139817. doi: 10.1371/journal.pone.0139817. PMID: 26485706; PMCID: PMC4618935. 

5. Venn-Watson, S., Lumpkin, R. & Dennis, E.A. Efficacy of dietary odd-chain saturated fatty acid pentadecanoic acid parallels broad associated health benefits in humans: could it be essential?. Sci Rep 10, 8161 (2020). https://doi.org/10.1038/s41598-020-64960-y. 

6. Dabrowski G and Konopka I. Update on food sources and biological activity of odd-chain, branched and cyclic fatty acids –– A review. Trends in Food Science & Technology 2022. 119: 514-529. https://doi.org/10.1016/j.tifs.2021.12.019. 

7. 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. Annals of Internal Medicine. 2014. https://doi.org/10.7326/M13-1788. 

8. Astrup, A, Magkos, F, Bier, D. et al. Saturated Fats and Health: A Reassessment and Proposal for Food-Based Recommendations: JACC State-of-the-Art Review. J Am Coll Cardiol. 2020 Aug, 76 (7) 844–857.https://doi.org/10.1016/j.jacc.2020.05.077. 

9. de Lorgeril M, Renaud S, Mamelle N, et al. Mediterranean alpha-linolenic acid-rich diet in secondary prevention of coronary heart disease. Lancet. 1994 Jun 11;343(8911):1454-9. doi: 10.1016/s0140-6736(94)92580-1. Erratum in: Lancet 1995 Mar 18;345(8951):738. PMID: 7911176. 

10. Fitó M, Guxens M, Corella D, et al. Effect of a traditional Mediterranean diet on lipoprotein oxidation: a randomized controlled trial. Arch Intern Med. 2007 Jun 11;167(11):1195-1203. doi: 10.1001/archinte.167.11.1195. PMID: 17563030. 

11. Ikezaki H, Lim E, Cupples A, et. al. Small dense low-density lipoprotein cholesterol is the most atherogenic lipoprotein parameter in the Prospective Framingham Offspring Study. JAHA. 2021, 10:e019140. https://doi.org/10.1161/JAHA.120.019140. 

12. Goltz SR, Campbell WW, et al. Meal triacylglycerol profile modulates postprandial absorption of carotenoids in humans. Molecular Nutrition and Food Research. 2012; 56(6):866-877. https://doi.org/10.1002/mnfr.201100687.