While I am a fully licensed physician in Kansas, this communication does not constitute personal medical advice or establish a physician-patient relationship. See your own physician to discuss your particular diagnosis and treatment
Warning: this is a technical post, but not out of reach for most.
Heart rate variability The more your heart rate varies, the more resilient you are to adapt to changing conditions. A higher heart rate variability indicates that your sympathetic and parasympathetic nervous system is likely well-balanced. If you have a very low heart rate variability, you may have some form of chronic stress or inflammation and may be at risk for chronic disease. Low heart rate variability has been associated with increased risk of cardiovascular disease, diabetes, inflammation, obesity, mental health disorders, and complications with SARS-CoV-2 infection.
The vagus nerve plays a role in the inflammatory reflex and controls immune responses. The vagus nerve monitors peripheral inflammation and dampens the immune response. Afferent vagus nerve fibers sense peripheral inflammatory molecules and convey signals to the brain. Efferent vagus nerve fiber transmission results in cholinergic output to the spleen, liver, and GI tract. The vagus nerve regulates immune activation and suppresses pro inflammatory cytokine release from other cells. The vagus nerve helps to decrease inflammation.
C-reactive protein (CRP) is a protein produced by the liver in response to inflammation. Levels of C-reactive protein increase following the secretion of interleukin-6 (also a cytokine) from macrophages and T cells. This protein binds to the surface of dead cells and enhances the ability of antibodies and phagocytic cells to remove pathogens. Higher levels of CRP are associated with greater risk of hypertension, diabetes, and cardiovascular disease. The high-frequency component of heart rate variability predicted the level of CRP when measured. The lower the heart rate variability, the higher the CRP level.
Higher levels of fasting insulin were associated with lower heart rate variability. Low-carb, high-fat eating will lower your fasting insulin level over time, which could improve your heart rate variability.
Oxytocin has been found to increase high-frequency heart rate variability in humans, improve mood, and decrease the release of cortisol, reduce inflammation, elevate pain threshold, and stimulate endocannabinoid production and the production of the “feel-good” neurotransmitters: dopamine, serotonin, endorphins, and oxytocin. You can increase oxytocin by singing, listening to music, making love, receiving or giving massage, hugs, and petting your dog. *Be aware that oxytocin is activated by vitamin D. Many autistic children have a low vitamin D level. Possibly 50% of the general population has vitamin D deficiency. Vitamin D naturally increases dopamine levels in the brain. Vitamin C is a cofactor in the production of oxytocin also. Fruits, vegetables, and supplements can increase your vitamin C level. Magnesium increases the action of oxytocin at the oxytocin receptor. Lactobacillus reuteri probiotic significantly increases oxytocin levels in the brain through the work of the vagus nerve.
Heart rate variability decreases with age in general. In your 20s, your heart rate may vary by 40 points, whereas at age 65 it may only vary by 20 points. You can look at heart rate variability charts for averages across age ranges. It is not useful to compare your own heart rate variability to that of someone else. It is useful for you to track changes in your heart rate variability with lifestyle intervention over time.
Heart rate variability is influenced by the volume and intensity of training and the balance between rest and workout days. It is also greatly affected by diet and nutrition, alcohol, sleep habits, and stress level. When you avoid eating close to bedtime this allows your body to focus on restorative processes instead of digestion. Use of alcohol can suppress heart rate variability for 4-5 days. Of course, chronic health problems, genetics, and age also affect heart rate variability.
Tips to improve heart rate variability Exercise and train appropriately, good nutrition at the right time, low-carb, high-fat diet, fish consumption, multiple vitamins, weight loss, adequate hydration, avoidance of alcohol, sleep well and consistently, natural light exposure, cold thermogenesis, intentional breathing, mindfulness and meditation, and gratitude journaling.
Some heart rate variability monitoring device examples below if you choose to use them: WHOOP bands (expensive monthly fee), Oura rings (expensively cost, also monthly fee), apple watch, Fitbit charge 5, and Polar H10 chest strap.
This post speaks about health optimization. If you have a low heart rate variability, you may have a chronic condition that likely needs addressed with, at a minimum, some of the tips described above. Even without understanding the technical details of nerve function and the autonomic nervous system, if you search your heart, it would make sense to implement these positive changes in your lifestyle.
I hope this information helps you and your loved ones!
Jason Williams, D.O.