Regardless of source, Vitamin D is good for your heart. If you have one.
University
of South Australia
In
the first study of its kind, researchers from the UniSA's Australian Centre for
Precision Health at SAHMRI have identified genetic evidence for a role of vitamin
D deficiency in causing cardiovascular disease.
The
study, which is published in European Heart Journal today,
shows that people with vitamin D deficiency are more likely to suffer from
heart disease and higher blood pressure, than those with normal levels of
vitamin D*. For participants with the lowest concentrations the risk of heart
disease was more than double that seen for those with sufficient
concentrations.
Globally,
cardiovascular diseases (CVDs) are the leading cause of death worldwide, taking
an estimated 17.9 million lives per year. In Australia, CVD accounts for one in
four deaths and costs the Australian economy five billion dollars each year,
more than any other disease.
Low concentrations of vitamin D are common in many parts of the world, with data from the UK Biobank showing that 55 per cent of participants have low levels of vitamin D (<50 nmol/L) and 13 per cent have severe deficiency (<25 nmol/L).
Low
levels of vitamin D are recorded by an estimated 23 per cent of people in
Australia, 24 per cent of people in the US, and 37 per cent of people in
Canada.
Chief
investigator, UniSA's Prof Elina Hyppönen says appreciating the role of vitamin
D deficiency for heart health could help reduce the global burden of
cardiovascular disease.
"Severe
deficiency is relatively rare, but in settings where this does occur it is very
important to be proactive and avoid negative effects on the heart. For example,
deficiency can be a problem for people living in residential care who may have
limited exposure to sun," Prof Hyppönen says.
"We
can also get vitamin D from food, including oily fish, eggs and fortified foods
and drinks. This said, food is unfortunately a relatively poor source of
vitamin D, and even an otherwise healthy diet does not typically contain
enough.
"If
we don't get any vitamin D through the sun, this is one of the rare nutrients
for which we sometimes need to take a daily supplement to keep up with the
requirements.
"Understanding
the connection between low levels of vitamin D and CVD is especially important,
given the global prevalence of this deadly condition.
"Our
results are exciting as they suggest that if we can raise levels of vitamin D
within norms, we should also affect rates of CVD. In our study population, by
increasing vitamin D-deficient individuals to levels of at least 50 nmol/L, we
estimate that 4.4 per cent of all CVD cases could have been prevented."
This
large-scale Mendelian study used a new genetic approach that allowed the team
to assess how increasing levels can affect CVD risk based on how high the
participants actual vitamin D levels were. The study used information from up
to 267,980 individuals which allowed the team to provide robust statistical
evidence for the link between vitamin D deficiency and CVD.
"It
is not ethical to recruit people with vitamin D deficiency to a randomised
controlled trial and to leave them without treatment for long periods. Prof
Hyppönen says.
"It
is exactly this type of difficult setting which demonstrates the power of our
genetic approach, given we can show how improving concentrations affects the
risk in those most in need, without exposing participants to any harm.
"Those
with the lowest concentrations are likely to have the strongest effects, yet a
population-wide approach to eradicate vitamin D deficiency could reduce the
global burden of CVDs."