A quick google search will produce a range of dietary strategies for heart disease, most of them high-carb and low-fat. But is cutting fat and increasing carbs really the best way to mitigate cardiovascular risk factors?
While high cholesterol, inflammation, and triglycerides are all known factors contributing to heart disease, one important piece to the puzzle that often goes unmentioned— the impact that dysregulated blood sugar can have on heart health.
Research shows that managing blood sugar could be a powerful way to reduce the risk of cardiovascular disease, with known pathologies already linking diabetes and heart disease.
In this article, we'll look at how blood sugar and insulin impact heart health, why concerns around LDL cholesterol levels are unwarranted, and why low-carb dieting may be your best bet for mitigating the threat of cardiovascular disease.
Why Managing Blood Sugar Is Crucial For Heart Health
The connection between blood sugar and cardiovascular disease is woefully underrepresented in education regarding heart health. When you look at the data, however, there is a clear place for high blood glucose and hyperinsulinemia in the pathology of heart disease.
According to data published in 2020 by the US National Institutes of Health, approximately 45% of the total adult population in the United States has been diagnosed with either diabetes or prediabetes (with type 2 diabetes accounting for 90-95%). And of all of the complications that can come with diabetes, cardiovascular disease is the leading cause of death, with diabetics twice as likely to experience heart disease or stroke than those without diabetes.
Furthermore, findings from the Women's Health Study showed that across all ages studied; diabetes resulted in the highest risk for coronary heart disease – with a tenfold increased risk for women younger than 55.
All in all, research shows that of the many contributing risk factors for heart disease, uncontrolled blood sugar is likely one of the most detrimental – if not the most detrimental.
But how do blood sugar and heart disease relate to one another?
Uncontrolled Blood Sugar, Heart Disease, And Low-Carb Diets
Uncontrolled blood sugar, whether in the case of diabetes or not, results in two primary metabolic abnormalities:
- A spike in blood glucose
- An increase in circulating insulin
Both of these factors can cause damage to your heart and impair normal physiological function.
High Blood Glucose
Under normal circumstances, when your blood sugar levels spike (due to a meal that's high in sugar or refined carbohydrates), your cells will respond by opening their glucose doors and letting in the excess sugar to be used as energy or stored as fat. This process is regulated by the hormone insulin, which acts as a chauffeur, knocking on the glucose doors to your cells.
However, in the case of diabetes or insulin resistance, your cells don't hear the knock, and blood sugar can remain chronically high. When excess blood sugar is stuck in circulation, it eventually starts to create damage to your vascular walls, which then sets the stage for inflammation, oxidation, and atherosclerosis.[5,6]
When blood sugar rises, your body responds by pumping out more insulin to try to usher that excess glucose out of your blood and into your cells. Unfortunately, if your cells are resistant to insulin, then the feedback loop, which would normally shut off the insulin-valve, doesn't get initiated, which results in high levels of both glucose and insulin in the blood.
The long-term effects of high insulin (hyperinsulinemia) can directly impact heart health. For example, research shows that chronically high insulin may contribute to:[7,8,9,10]
- Hypertension (high blood pressure)
- Endothelial dysfunction (constriction of blood vessels causing chest pain)
- Atherosclerotic plaque formation
- Overall increased risk for heart disease
Although insulin is most well-known for its role in regulating blood sugar, this hormone actually carries out several other functions which may contribute to its detrimental impact on heart health. For example, insulin suppresses a key enzyme involved in vasodilation (blood vessel dilation) and stimulates calcium influx into smooth muscle cells. When taken out of their normal homeostasis, both of these activities could contribute to heart health complications.
So it appears that although there are several risk factors to be aware of for heart disease, controlling blood sugar should be at the top of our list. And research shows that low-carb dieting is a powerful way to reduce blood sugar and help resensitize your cells to insulin.
But What About LDL Cholesterol?
Of course, one of the first questions that come to mind when people hear about low-carb and heart disease is, "what about LDL cholesterol?"
First, it's important to note that clinical trials show that the risk of heart disease associated with high blood glucose is far greater than the risk associated with other markers such as total cholesterol and LDL cholesterol concentrations.
Furthermore, the threat that LDL cholesterol levels play in heart health is often overblown and misunderstood, and although people on low-carb diets may experience a small rise in their LDL profile, most individuals won't experience clinically significant increases.[12,13]
It's also worth mentioning that low-carb doesn't necessarily mean high-fat. While most people on low-carbohydrate or ketogenic diets increase their fat intake, they also increase their intake of protein to displace the carbs.
So let's take a deeper look at LDL cholesterol and its relationship to heart health and low-carb dieting.
Understanding LDL-C, LDL-P, and Particle Size
Perhaps the most confusing aspect of "cholesterol" is that this term is used as a catch-all for all manner of lipoproteins. Lipoproteins come in many shapes and sizes, and the lipoprotein's structure (and amount) determines whether it's beneficial or harmful.
LDL cholesterol is known as the artery-clogging lipoprotein that lodges into your vascular walls creating atherosclerosis. While this is certainly an outcome that can happen when LDL levels are high, both the structure and the amount of LDL matter greatly.
More specifically, there is a measurement called LDL-P which identifies the number of LDL particles in your blood, as opposed to the number of lipoproteins themselves (lipoproteins can carry varying numbers of particles).
Furthermore, the size of your LDL also significantly affects its ability to contribute to atherosclerotic plaques. Smaller, more dense LDL particles can easily lodge into your vascular tissue, while larger, fluffier LDL is much more harmless.
Studies show that while a low-carbohydrate diet may slightly increase LDL levels, it can significantly decrease the LDL-P (the number of particles) and significantly increase LDL particle size. In other words, the net change in LDL is cardio-protective, as opposed to detrimental to heart health.
Triglycerides, Low HDL, and Dense LDL: The Real Threats
While LDL seems to take the spotlight when it comes to blood lipids and heart disease, the real threat lies in the combination of high triglycerides, low HDL cholesterol, and high levels of small, dense LDL cholesterol.
These three markers serve as a much more powerful predictor of heart disease than LDL levels alone. In fact, research from over 25 years ago shows that LDL levels alone show no significant correlation with heart disease, while the presence of small, dense LDL is associated with triple the risk for heart attack.
So what happens to these markers when someone switches to a low-carb diet? Research shows that cutting carbs often results in lowered triglycerides, increased HDL cholesterol, and, as mentioned – larger, fluffier LDL cholesterol.
In short, a low-carb diet produces a more beneficial blood lipid profile in those with dyslipidemia.
Other Benefits of Low-Carb Dieting For Heart Disease
Promotes Weight Loss
Obesity is one of the most common risk factors that set the stage for heart disease and other metabolic conditions. Excess body fat can increase blood pressure, inflammation, dyslipidemia, and insulin resistance – all of which have a role to play in cardiovascular disease.
Many people find that when they switch to a low-carb diet, they begin to lose stubborn weight that's been plaguing them for years. There are many theories as to why the low-carb diet works for weight loss, including:[18,19,20]
- Increased satiety
- More body fat burned for energy
- Less energy stored as body fat
- Increased thermogenesis
Regardless of the exact mechanism, studies show that low-carb is superior to standard weight loss diets when it comes to shedding pounds.
Another risk factor for heart disease is high blood pressure. When blood pressure rises, it can damage your arteries and decrease blood and oxygen flow to your heart, setting the stage for heart disease.
Studies show that following a low-carb diet can significantly reduce blood pressure in people with hypertension, alleviating this stressor on your heart.
If you're concerned about cardiovascular health and want to mitigate your risk for heart failure, heart attack, or any other heart-related condition, then it's worth trying a low-carb or keto diet.
These diets are rich in heart-healthy options like fiber, polyunsaturated fats, and mono-unsaturated fats, and as the research shows, can help lower several risk factors for heart disease.
If you're new to watching your carbohydrate intake, it can be helpful to work with a coach that can guide you, which is where BioCoach comes in. On the BioCoach App, you'll receive all the guidance you need to get started and stay the course with your new dietary program.
- Dugani, Sagar B., et al. "Association of lipid, inflammatory, and metabolic biomarkers with age at onset for incident coronary heart disease in women." JAMA cardiology 6.4 (2021): 437-447.
- Berger, Amy, and Eric Thorn. "Can low-carbohydrate diets be recommended for reducing cardiovascular risk?." Current Opinion in Endocrinology & Diabetes and Obesity 29.5 (2022): 413-419.
- Paneni, Francesco, et al. "Diabetes and vascular disease: pathophysiology, clinical consequences, and medical therapy: part I." European heart journal 34.31 (2013): 2436-2443.
- Aronson, Doron, and Elliot J. Rayfield. "How hyperglycemia promotes atherosclerosis: molecular mechanisms." Cardiovascular diabetology 1.1 (2002): 1-10.
- Yip, Jeannie, Francesco S. Facchini, and Gerald M. Reaven. "Resistance to insulin-mediated glucose disposal as a predictor of cardiovascular disease." The Journal of Clinical Endocrinology & Metabolism 83.8 (1998): 2773-2776.
- Kolb, Hubert, et al. "Insulin: too much of a good thing is bad." BMC medicine 18.1 (2020): 1-12.
- Wang, Xukai, et al. "The injurious effects of hyperinsulinism on blood vessels." Cell biochemistry and biophysics 69.2 (2014): 213-218.
- Holden, Sarah E., et al. "Glucose‐lowering with exogenous insulin monotherapy in type 2 diabetes: dose association with all‐cause mortality, cardiovascular events and cancer." Diabetes, Obesity and Metabolism 17.4 (2015): 350-362.
- Foley, Peter J. "Effect of low carbohydrate diets on insulin resistance and the metabolic syndrome." Current Opinion in Endocrinology, Diabetes, and Obesity 28.5 (2021): 463.
- Shai, Iris, et al. "Weight loss with a low-carbohydrate, Mediterranean, or low-fat diet." New England Journal of Medicine 359.3 (2008): 229-241.
- Yancy Jr, William S., et al. "A low-carbohydrate, ketogenic diet versus a low-fat diet to treat obesity and hyperlipidemia: a randomized, controlled trial." Annals of internal medicine 140.10 (2004): 769-777.
- Sacks, Frank M., and Hannia Campos. "Low-density lipoprotein size and cardiovascular disease: a reappraisal." The Journal of Clinical Endocrinology & Metabolism 88.10 (2003): 4525-4532.
- Athinarayanan, Shaminie J., et al. "Impact of a 2-year trial of nutritional ketosis on indices of cardiovascular disease risk in patients with type 2 diabetes." Cardiovascular diabetology 19.1 (2020): 1-13.
- Austin, Melissa A., et al. "Low-density lipoprotein subclass patterns and risk of myocardial infarction." Jama 260.13 (1988): 1917-1921.
- Unwin, David, et al. "Insights from a general practice service evaluation supporting a lower carbohydrate diet in patients with type 2 diabetes mellitus and prediabetes: a secondary analysis of routine clinic data including HbA1c, weight and prescribing over 6 years." BMJ Nutrition, Prevention & Health 3.2 (2020): 285.
- Noakes, Manny, et al. "Comparison of isocaloric very low carbohydrate/high saturated fat and high carbohydrate/low saturated fat diets on body composition and cardiovascular risk." Nutrition & metabolism 3.1 (2006): 1-13.
- Halton, Thomas L., and Frank B. Hu. "The effects of high protein diets on thermogenesis, satiety and weight loss: a critical review." Journal of the American college of nutrition 23.5 (2004): 373-385.
- Ebbeling, Cara B., et al. "Effects of dietary composition on energy expenditure during weight-loss maintenance." Jama 307.24 (2012): 2627-2634.
- Dyson, P. A., S. Beatty, and D. R. Matthews. "A low‐carbohydrate diet is more effective in reducing body weight than healthy eating in both diabetic and non‐diabetic subjects." Diabetic Medicine 24.12 (2007): 1430-1435.
- Unwin, David J., et al. "Substantial and sustained improvements in blood pressure, weight and lipid profiles from a carbohydrate restricted diet: an observational study of insulin resistant patients in primary care." International Journal of Environmental Research and Public Health 16.15 (2019): 2680.