Evidence shows that heart failure is associated with low blood levels of vitamin D. When a person suffers from heart failure, the heart is unable to pump enough blood to supply the needs of the body. Heart failure is a relatively common condition in the elderly population over age 65, occurring in up to 10 percent of people in that age group.
Explaining heart failure
Heart failure occurs because the force of the heart muscle is decreased. Not all the blood is pushed out of the chambers of the heart when the muscle contracts. When the heart is called on to work harder during exercise, it can’t.
The body tries to put out sufficient blood by increasing the heart rate, which strains the heart muscle even more. Ultimately, the heart enlarges. This makes it even more likely that the heart muscle will fail, especially when it is most needed during exercise.
Heart failure can be caused by these factors:
Heart attack with loss of significant muscle.
High blood pressure.
Disease of the heart valves that prevent blood from flowing backward to the heart chamber that has just pumped it out. If a valve allows blood to flow backward, it means the heart has to work harder to get the same volume of blood to move through the heart and into the body.
Cardiomyopathy, a diminished function of the heart muscle caused by a number of abnormalities, including malnutrition, decreased but not complete cessation of blood flow to the heart muscle, inflammation, diabetes, and too much alcohol consumption.
Identifying heart failure signs and symptoms
When heart failure occurs, the patient suffers from several debilitating signs and symptoms:
Fluid in the lungs
Orthopnea, the need to sleep with the head raised on multiple pillows to breathe
Pulmonary edema, severe breathlessness resulting from fluid accumulation in the lungs
Shortness of breath
Swelling of the abdomen
Swelling of the feet, ankles, and legs
Treatment of heart failure requires the use of drugs called angiotensin-converting enzyme inhibitors. Salt and fluid intake is also carefully monitored. Some exercise can help improve heart function. Patients may require an implantable cardioverter defibrillator, a device that is implanted under the skin and shocks the heart if it loses its normal rhythm. The only certain treatment for a heart that is failing or has failed is transplantation of a new heart.
Heart failure is progressive. The heart muscle usually gets weaker over time. Treatment may help, but the prognosis is poor without a heart transplant.
Examining vitamin D’s role in heart health
A number of findings suggest that vitamin D plays an important role in preventing heart failure and that a lack of vitamin D increases the severity of the heart failure:
Patients with heart failure have low serum 25-hydroxyvitamin D levels.
The number of deaths due to heart failure were almost three times higher in vitamin D-deficient subjects compared to those with higher serum 25-hydroxyvitamin D (25-hydroxyvitamin D higher than 30 ng/ml [75 nmol/L]). Also, deaths from heart failure are more common in winter when skin vitamin D production is low.
Heart muscle cells have vitamin D receptors, and calcitriol has direct effects on cardiac muscle cells grown in culture.
The reasons that vitamin D might prevent heart failure include the following:
High vitamin D status is associated with improvements in many of the conditions that lead to heart failure, such as coronary artery disease and high blood pressure, as well as diabetes and obesity.
Calcitriol vitamin D inhibits the renin-angiotensin-aldosterone system, causing salt and water retention. Increased salt and water make heart failure worse by increasing blood pressure.
The excessive levels of parathyroid hormone that occur in vitamin D deficiency may damage the heart muscle by lengthening and thinning the heart muscles. Too much parathyroid hormone can also cause fibrosis, the development of excessive fibrous connective tissue that replaces heart muscle.
Calcitriol suppresses the inflammatory responses including the production of cytokines. In the heart, cytokines destroy heart muscle.
No studies have yet been done showing that vitamin D supplementation improves the prognosis of people with heart failure or at high risk of heart failure. When people have heart failure they are ill and less active, and this may be why the blood levels of vitamin D are low. So rather than low levels of vitamin D causing the heart failure, it may simply be an effect of the primary disease.