Vitamin D Treatment in Cardiovascular Disease
Vitamin D insufficiency is a common condition. However, it is frequently undiagnosed, as the vitamin D blood test is costly at approximately $120/test. Despite living in a tropical country like Singapore, many people prefer to stay indoors. Vitamin D absorption can also be reduced by application of sunscreens. Based on an epidemiological study in tropical countries, vitamin D insufficiency can account up to 80% of the population .
Vitamin D is essential in bone health, it also regulates the immune, cardiovascular and neuromuscular systems. Our body manufactures vitamin D only after skin exposure to sufficient sunlight. Darker skinned people absorb less sunlight, so they get lesser vitamin D from sun exposure compared to light-skinned people. Vitamin D is extracted from the blood by fat cells, altering its release into the circulation. Obese people with a body mass index of greater than 30 often have lower blood levels of vitamin D.
Vitamin D insufficiency has been linked to cardiovascular diseases, many studies have been published showing the importance of having adequate level of vitamin D in improving cardiac health. Therefore, vitamin D therapy can be an additional treatment regime in improving the outcome of cardiac patients if there is insufficiency.
A usual normal level of serum vitamin D is 75 – 249 nmol/L or (30-99 ng/ml).
Vitamin D deficiency is defined as < 25nmol/l (10ng/ml)
Vitamin D insufficiency is defined as 25-74.9nmol/l (10-29.9 ng/ml)
The bone-centric guidelines recommend a target vitamin D concentration of (50nmol/L) (20ng/mL), and age-dependent daily vitamin D doses of 400-800IU. The guidelines focused on pleiotropic effects of vitamin D recommend a target Vitamin D concentration of 75nmol/L (30ng/mL), and age, body weight, disease status, and ethnicity dependent vitamin D doses ranging between 400 and 2000IU/day .
In clinical practice, I test vitamin D levels at least once for my cardiac patients. On average, out of my 10 cardiac patients, 7 will have vitamin D insufficiency.
One example is a 42-year old lady, thin build who worked as a property agent presented with vasovagal dizziness, breathlessness and calcaneal spur had an initial vitamin D level of 22.5 nmol/l (deficient). Her heel pain, cardiac and vasovagal symptoms resolved after 6 months of vitamin D therapy. With 2000iu/daily dose, her vitamin D level was restored to 83nmol/l.
Another 34-year old man, obese with BMI of 32, worked in an egg factory, sedentary in lifestyle, and had vitamin D level of 46nmol/l. He was presented with angina due to moderate coronary disease and vasospasm.
An outdoor person who enjoy going under the sunlight daily will have a vitamin D level in the range of 80-140 nmol/l. One patient of mine who is a 61 year of Caucasian man living in Singapore who enjoys outdoor tracking, and goes to the beach for sunbathing weekly, has a serum vitamin D level of 137.5 nmol/l.
For patient with more severe vitamin D deficiency, oral supplementation with high dose D3 i.e. D-Cure® 25000iu twice weekly would often restore the normal level in 2-3 months. For patient with lesser insufficiency, oral D3 supplementation 1000 – 2000iu daily would normally increase the vitamin D levels by 10-20nmol/l/month. Sunlight exposure and diet modification are important aspect in the management.
Current data suggests that normalization of vitamin D level in deficient individuals could play a role in the treatment of a number of cardiovascular conditions. Study has shown a direct link of vitamin D deficiency on smooth muscle calcification and proliferation that could negatively impact cardiovascular health and caused hypertension. In an analysis of NHANES III 1988–1994, low vitamin D was associated with cardiovascular disease. In a prospective case-control study between 1993 and 1999 of 18,225 US men (Health Professionals Follow-Up Study), low vitamin D was associated with a higher risk of myocardial infarction in comparison with sufficient vitamin D after multivariate adjustment A prospective study of the Integrated Intermountain Healthcare system database of 41,504 patients has shown an association between vitamin D deficiency and an increase in the prevalence of diabetes, hypertension, hyperlipidemia, and peripheral vascular disease (P < 0.0001) . In a large prospective study (n = 10,170), low vitamin D levels were found to be associated with increased risk of ischemic heart disease, myocardial infarction, and early death during 9 years of follow-up. In a prospective cohort study of 3258 patients in Germany with a median follow-up of 7.7 years showed that low vitamin D level is independently associated with higher all-cause mortality (HR 2.08; 95% CI 1.60–2.70) and cardiovascular mortality (HR 2.22; 95% CI 1.57–3.13).
It is hypothesized that vitamin D deficiency increases blood pressure through the renin-angiotensin system which leads to hypertension, cardiac hypertrophy and increased water intake. Animal study results indicate vitamin D deficiency is associated with the development of hypertension and accelerated atherosclerosis. Another basic study revealed that vitamin D-deficient male rats have increased systolic blood pressure, superoxide anion production, angiotensin II and atrial natriuretic peptide with observed changes in 51 cardiac gene expressions important in the regulation of oxidative stress and myocardial hypertrophy
Current evidence suggests a higher risk of cardiovascular diseases and risk factors with lower vitamin D levels. However, the benefit of vitamin D supplementation in healthy patients with normal vitamin levels are conflicting with many confounding biases. In the randomized placebo controlled VITAL trial involving 25871 healthy volunteers with normal baseline vitamin D level (31ng/ml), routine vitamin D supplementation did not result in a lower incidence cardiovascular events than placebo.
In conclusion, based on the current data, restoration of vitamin D level could play beneficial role in cardiac patients with insufficient levels. Testing vitamin D level can be useful in management of cardiovascular diseases.
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A Specialist’s Point of View – Written by Dr Eric Silvio Chong
Dr Eric Silvio Chong is currently a senior consultant interventional and cardiac device cardiologist at the Farrer Park Hospital. He has previously undergone overseas translational research fellowship in antiaging therapy for cardiovascular disease.
Dr Chong is subspecialised in and accredited in interventional cardiology and cardiac device procedures. He has conducted clinical and translational research in coronary angioplasty, coronary stents, protective kidney therapy during contrast procedure, heart rhythm disorders, atrial fibrillation and cardiac device management. His current research and clinical interest is in longevity enhancement treatment for patients with severe heart disease.
He is a elected fellow of several cardiology societies such as the Academy of Medicine of Singapore, European Society of Cardiology, American College of Cardiology, ASEAN Federation of Cardiology, Asia Pacific Society of Interventional Cardiology and Society of Cardiovascular Angiography and Interventions USA and European Heart Rhythm Society.
Dr Chong underwent advanced subspecialty training under world famous cardiologists in internationally renowned cardiac centers in Singapore National University Hospital, Taiwan Veterans General Hospital and London St Thomas Hospital in the past.