For maintaining healthy bones and muscles, vitamin D is an essential part of people’s diet. Vitamin D referred to as calciferol can be obtained through food, sun exposure, and supplements and is one of the only fat-soluble vitamins that can be both made by our bodies and be found in food sources. Because of these widely known benefits, many people have decided to take upon these vitamin D benefits and boost their intake through the best vitamin D supplements out there. But could too much vitamin D cause negative side effects? Is it possible that vitamin D is too good to be true?
In response, we’re going to explore vitamin D in more
detail, looking into the research behind this unusual vitamin and learn about
the best ways to take vitamin D supplements, including the recommended vitamin
D intake, what causes vitamin D deficiency, can it really prevent other health
conditions and what happens when you take too much vitamin D.
Vitamin D As Both Nutrient And Hormone
Vitamin D is remarkable because it’s both a nutrient and hormone. It’s not entirely a vitamin but rather a group of steroid molecules that are generated from exposure to light and food. Our bodies both produce and need this vitamin to absorb calcium, which assists in normal bone mineralization and prevents involuntary muscle contractions. As a nutrient, our bodies are able to metabolize and store this vitamin in our bodies. It also acts as a prohormone or a precursor to hormone production. When Vitamin D enters our system, it can produce multiple types of hormones due to the various chemical reactions our metabolism goes through, including:
Cholecalciferol: Known
as vitamin D3, this vitamin assists in calcium homeostasis and acts as a
steroid hormone by interacting with the vitamin D receptors within our
metabolism. This version of vitamin D helps many people maintain elderly bone
density and lowers the risk of fractures.
Ergocalciferol: Known
as vitamin D2, this vitamin forms from plant-derived materials that are exposed
to sunlight, including mushrooms. Our bodies do not naturally produce vitamin
D2 but are often prescribed as a supplement for conditions such as
hypoparathyroidism and rickets.
Calcidiol: When
our bodies metabolize vitamin D3, the liver goes through the process of
hydroxylation, turning it into the enzyme calcidiol, binding with the vitamin D
receptors within our blood to mineralize our bones.
Calcitriol:
Calcidiol can be further converted into calcitriol, an active hormone of
vitamin D that also binds with the vitamin D receptors. It helps increase blood
calcium, which assists with gene expression to help improve bone density and
muscle contractions.
All of these versions, primarily concerned with vitamin D3
and D2, all assist with the body’s metabolism in various ways. Cholecalciferol
is the reaction that occurs when our bodies first interact with Vitamin D, and
from there, our livers convert the reaction to calcidiol. The kidneys convert
the substance after that to calcitriol, the active hormone that binds to our
receptors and helps fortify our bones and muscles.
How Vitamin D Transfers Into Our Blood
When our bodies take in vitamin D, our vitamin D receptors
help transcribe our gene expression, containing hormone-binding and DNA-binding
domains. These components work with our DNA to provide the essential
instructions for utilizing the vitamin D benefits within our system. As for the
physiological effects of vitamin D, the effects can most often be found in the
intestines. This hormone stimulates the formation of phosphate and magnesium
ions and assists the intestines in absorbing calcium. Vitamin D, in these
cases, works to increase the expression of our proteins that help transport
calcium, phosphate, and magnesium into our blood. It goes through a specific
process to provide these benefits, including:
The
Intestines: The lumen, or inside layer of the intestine,
works with the proteins produced by the presence of vitamin D, or calcitriol,
across to the epithelial cells.
Epithelial
Cells: Our epithelial cells, located along the outer membrane of
the intestines, help transfer those proteins into our bloodstream. Calcium is
transferred alongside these proteins through calbindin transporters and makes
vitamin D absorption easier.
Bloodstream: From
there, our bloodstream help carries these vitamins and minerals throughout our
body and delivers these nutrients and hormones to specific areas, including our
bones, muscles, and other areas of the body.
However, it isn’t just the intestines that deliver the
benefits of vitamin D. In fact, vitamin D receptors can be found throughout all
cells in our body. Because of this, vitamin D benefits may also have a bigger
physiological effect on the growth and differentiation of many types of cells
and may not just contribute to mineral homeostasis and bone function.
Studies in Vitamin D and Its Health Conditions
Vitamin D has been commonly associated with various
diseases and conditions, often due to how vitamin D receptors are present
within almost all cells in the body. Its role in gene expression and regulation
means that vitamin D also impacts brain development and function, diabetes
development, cardiovascular disease, and cancer. Because vitamin D is a
precursor hormone that regulates gene expression, the role that vitamin D has
in our health is ever-complex and evolving. Below, we’ll look at multiple
studies on the effects of vitamin D benefits and its various health conditions:
Vitamin
D and Bone Health: Because of its ability to carry calcium and
other minerals throughout the system, it’s considered one of the best ways to
protect people’s bone health. Many studies often cited for its benefits focus
on its ability to maintain cellular function, promote mineralization, and
maintain calcium and phosphorus concentrations. From these benefits, it’s most
often recommended for those at higher risk of developing a vitamin D deficiency
or at a higher risk of developing conditions such as osteoporosis.
However, some studies looking into the best vitamin D
supplements for preventing falls and fractures show that it doesn’t prevent the
risk. The study observed the effects of vitamin D supplements on how it boosts
bone mineral density and its ability to prevent bone fractures. These studies
concluded that the best vitamin D supplements didn’t affect the rate of falls
and fractures among those with bone conditions or have a higher risk of bone
fractures, such as the elderly. However, organizations such as the National
Osteoporosis Society concluded that despite the risks, it does not change the
recommended vitamin D intake for those at risk for osteoporosis and other bone
conditions.
Cholesterol
Levels and Vitamin D: Women going through post-menopause often suffer
from poor lipid profiles, increasing bad cholesterol and triglycerides.
However, recent studies from the Women’s Health Initiative trials showed that
women supplementing with the best vitamin D supplements over the course of two
years had not only higher levels of vitamin D in their blood but also
experienced better lipid profiles. Because of the introduction of better lipid
levels with calcium and vitamin D intake, the study also concluded that the
risk of hip fractures among women was decreased compared to those under the
placebo effect.
Heart
Disease and Vitamin D: Those concerned about the effects of
heart disease should be aware that although vitamin D tablets can increase bone
density, they may not protect people against cardiovascular disease. A meta-analysis
was performed on randomized clinical trials that included more than 83,000
participants. The previous studies cited that the effects that vitamin D has on
nutrient transportation and gene expression that could decrease the risk of
heart disease among men and women. However, the meta-analysis concluded that
vitamin D supplementation doesn’t provide any protection against cardiovascular
disease due to the measures used to perform the trials.
Vitamin
D and Arthritis: When it comes to connecting vitamin D
supplementation with arthritis, some research has shown that people with lower
levels of vitamin D are associated with a higher risk of developing rheumatoid
arthritis. According to this study, vitamin D plays a huge role in regulating
the immune system and thus can play a huge role in the development of
autoimmune disorders. Due to this reasoning, some participants experienced less
inflammation throughout the joints when increasing their vitamin D levels.
However, because the studies connecting these two factors remain inconsistent,
it cannot be concluded.
Diabetes
and Vitamin D: People wishing to prevent the onset of type 2
diabetes may be disappointed, as vitamin D supplements in recent studies do not
reduce the risk; according to some studies, the introduction of the best
vitamin D supplements had no difference in those at risk of developing type 2
diabetes when compared to placebo. However, some studies in previous cases
believe that vitamin D may be able to increase insulin sensitivity for those
with type 2 diabetes, thus reducing the risk of insulin resistance associated
with this condition. Within these cases, type 2 diabetes usually occurs
alongside the presence of a vitamin D deficiency, which contributes to numerous
other health problems, including cancer and osteoporosis. Thus, many of these
cases remain inconclusive.
Vitamin
D and Asthma/Allergies: When comparing the rates of vitamin D
levels with those who have asthma and allergic conditions, many of the findings
remain inconclusive, as the connections between these two factors remain vague.
One study reports that the best vitamin D supplements can be used as an
adjective treatment for managing asthma when considering its other vitamin D
benefits. However, the results of the study are concluded as being unreliable
due to the inability to define its role in asthma development. Other studies
also support the statement, as vitamin D3 supplementation did not support its
use for severe asthma in children and other allergic conditions.
Autism
and Vitamin D: Because of the impact vitamin D has on gene
expression, many studies have reported that inadequate levels of vitamin D in
pregnant women could potentially increase the risk of autism in children.
Studies from the University of Queensland report that mothers with a vitamin D
deficiency could increase the testosterone levels of male fetuses, impacting
proper neurodevelopment. However, some studies also prematurely conclude that
an increase in vitamin D levels may also increase the risk of neurodevelopmental
disorders. However, in these cases, the majority of studies conclude that the
role of vitamin D needs to be better defined to evaluate if it can reduce the
impact of autism spectrum disorder.
What Happens When You Take Too Much Vitamin D?
Vitamin D has been reported to have many benefits to our
metabolism, bones, and muscles, but for those interested in taking vitamin D
tablets, there is the potential to experience vitamin D toxicity resulting from
large doses. Vitamin D toxicity is created when the body isn’t able to regulate
the amount of vitamin D within the bloodstream. It causes a large buildup of
calcium in the blood, known as hypercalcemia. Hypercalcemia causes frequent
urination, nausea, vomiting, and weakness. This condition can progress to
kidney problems and bone pain, causing the formation of calcium stones.
Most often, higher recommended vitamin D intake is for
those who suffer from vitamin D deficiency. However, these higher doses are
often used under the care of your GP or physician for a specific amount of
time. If you believe you may have vitamin D deficiency, then your blood levels
should be monitored to prevent the risk of too much vitamin D.
The Recommended Vitamin D Intake In the UK
According to NHS, the recommended daily dose of vitamin D
for babies ages one year needs between 8.5 to 10 micrograms of vitamin D a day.
Children beyond the age and adults of one need ten micrograms a day, especially
for those who are pregnant, breastfeeding, and have a vitamin D deficiency.
However, the NHS recommends that for those who don’t have a vitamin D
deficiency, vitamin D should be received from the diet during the autumn and
winter months, while throughout the early spring to summer months, people can
receive their daily dose through sunlight. If you’re interested in taking
vitamin D tablets and have a risk of developing a vitamin D deficiency, then
you should speak with your GP for more information.
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