Vitamin D, which is a fat-soluble vitamin that is also called the “sunshine” vitamin, comes in two main forms, D-2 and D-3. It is an essential micronutrient, which is primarily derived from sunlight, which is vital for bone and teeth development, as well as for regular functioning of one’s immune system. Former studies have shown that aside from these functions, people that have low vitamin D levels also have a higher risk of developing cardiovascular disease.
In this new study, researchers have found that checking vitamin D levels is essential when looking at one’s cardiovascular risk.
According to the World Health Organization (WHO), cardiovascular diseases (CVDs) are one of the leading causes of death worldwide. An estimated 17.9 million people across the globe die due to complications of heart diseases each year. Simply put, CVDs are responsible for at least 32% of all deaths globally.
Former studies explain that there are a number of different reasons combined that heighten the risk of developing a CVD, like age, diet, lifestyle, family history, and several health conditions. But in this new study, researchers from Australia used a new analytical approach and have found that there is an additional factor that could possibly increase this risk of someone developing CVD.
Lead author of the study and director of the Australian Centre for Precision Health at the University of South Australian Cancer Research Institute, Professor Elina Hyppönen, helped outline the outcome of this new study to Medical News Today (MNT).
She said, “We found evidence that vitamin D deficiency can increase blood pressure and the risk of CVD.”
She added, “However, increasing vitamin D concentrations will only be helpful for those participants who ‘need it,’ and further benefits from elevating concentrations beyond the nutritional requirement are going to be modest, if they exist.”
The study appears in the medical publication Oxford Academic’s European Heart Journal.
Researchers Share ‘Exciting New Approach’
In this recent study, the research group focused on investigating whether there is a relationship between the risk of developing CVD and serum 25-hydroxyvitamin D, or 25(OH)D. It’s the serum 25(OH)D levels that are a marker for one’s vitamin D status.
To test out their hypothesis, the scientists used a particular analytical method to analyze the data they took from UK Biobank, which is a large prospective cohort study taken from people aged 37 to 73 in the United Kingdom.
The participants were also taken from 22 assessment centers around the United Kingdom between March 13, 2006 and October 1, 2009. They were asked to fill out questionnaires that provided broad information on health and lifestyle at baseline, while also providing blood samples for genetic and biomarker assays.
The research team also limited the data analyses for the study to unrelated individuals identified as white British, based on their genetic profiling and self-reports. In addition, the research group excluded participants that had mismatched information between genetic and self-reported sex.
Once they were done filtering the information, the scientists conducted genetic assays from individuals that had complete information on their 25(OH)D concentrations. They also collected variables such as age, sex, and time of sample collection as an extra precaution and safety measure, as they could affect the serum 25(OH)D measurements.
This information was collected from at least 295,788 participants.
What Did the Results Show?
The research group compared the results with participants of a control group that did not have a CVD diagnosis. They also conducted a secondary analysis to further the association between blood pressure and 25(OH)D concentration levels.
From the 267,980 participants that were surveyed, the researchers share that the average 25(OH)D concentration level was 50 nanomoles per liter (nmol/l).
The study also notes that following:
- 11.4% (32,868) of the participants had concentrations under 25 nmol/l
- 41.3% (119,243) of the participants had concentrations between 25 and 49.9 nmol/l
- 35.3% (101,848) of the participants had concentrations between 50 and 74.9 nmol/l
- 10.5% (30,314) of the participants had concentrations between 75 and 99.9 nmol/l
- 1.4% (4,110) of the participants had concentrations between 100 and 124.9 nmol/l
In addition, ‘Less than 0.1% of the participants had 25(OH)D concentration levels exceeding 125 nmol/l. Further analysis also showed that participants with serum 25(OH)D at 25 nmol/l had 11% higher risk of CVD than those with concentrations of 50 nmol/l.’
But researchers also found that there seemed that for those with higher concentration values showed a reduced likelihood of CVD occurrence. For instance, ‘participant with concentrations of 75 nmol/l had 2% lower odds of CVD when compared with those at 50 nmol/l.’
According to the research group, they noted that this phenomenon is a nonlinear association, which means that a change in the value of one entity does not necessarily ‘correspond with a constant change in the value of the other entity.’
Also, the research group managed to observe ‘similar nonlinear associations in the relationship between 25(OH)D concentrations and the blood pressure levels of the participants. At 25 nmol/l, there was a noticeable increase in blood pressure values when compared with 50 nmol/l.’
These findings are what led the scientists to conclude that a deficiency of vitamin D may possible increase the risk of developing CVD.
What Experts Have to Say
In order to better understand the study’s results, MNT spoke with experts to gather their thoughts.
According to board certified cardiologist at Providence Saint John’s Health Center in Santa Monica, CA, Dr. Rigved Tadwalker, he shared that the study had some clinical implications.
He explained that there has been confusion for a long time when it comes to vitamin D levels and looking at cardiovascular risk, as well as what is to be done with the information from the results.
He said, “[However, now], this study establishes that it is worthwhile to check vitamin D levels for the purpose of assessing cardiovascular risk and, moreover, supplementing vitamin D for those who are most deficient.”
Study Strengths and Limitations
As explained by the study authors, they explain that their study’s strength is precisely the novel way they analyzed their data. From their understanding, this is the first genetic analysis study that uses a nonlinear framework to look at the association of CVD risk with 25(OH)D.
Moreover, because of their meticulous practices, the study authors managed to reduce the chance findings and minimize biases.
Of course, the study also has certain limitations, the first of which was limiting the study participants to those of white British descent. This means that the results aren’t clear whether they would be applicable to people of other ethnicities. In addition, because the UK Biobank has a response rate of just 5%, it is not necessarily representative of the entire general U.K. population regardless of its rather large sample size.
Despite that, the study results could possibly lead scientists and expert to new ways and possibilities in the diagnosis and management of CVD.
Dr. Tadwalker concludes that regardless of these limitations, he is still rather optimistic with the results.
He explained, “People should discuss checking their vitamin D level with their physicians, as there is variability from one doctor to another as to whether this is checked as a matter of routine. If the vitamin D level is found to be significantly low, there is now evidence to suggest that increasing this level will decrease cardiovascular disease risk, including the risk of coronary artery disease and stroke.”
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