Vitamin d deficiency is less likely to lead
to weight gain. However, it can cause other health problems or unpleasant
symptoms, which are worth avoiding.
vitamin d, also known as the sun vitamin, is a hormone that your
body produces when your skin is exposed to sunlight. You can also get some
vitamin d from your diet, although few foods contain a lot of vitamin d.
Still, sun exposure and
diet alone are rarely enough to maintain optimal vitamin D levels (1).
Experts estimate that
about 50% of people worldwide have poor vitamin D levels, while as many as 1
billion people are deficient in vitamin D (1).
Maintaining optimal
vitamin D levels is essential for the health of bones, brains, and immune
systems. In addition, it has been suggested that adequate vitamin D levels may
help prevent unwanted weight gain. （2）。
This article reviews
whether vitamin d deficiency can lead to weight gain and, if so, how to
overcome it.
Link between vitamin d and weight gain
People who are
overweight and obese seem to be more likely to have lower vitamin D levels than
people whose body weight is in the "normal" body mass index (BMI)
range. This has led some to believe that low vitamin D levels may cause weight
gain (1, 3, 4).
Some studies seem to
support this theory. In one study, women took 1,000 IU (25 mcg) of vitamin d or
a placebo daily for 12 weeks.
By the end of the study,
women in the vitamin d group had lost 5.9 pounds (2.7 kg) of fat, while women
in the placebo group had lost about 1.1 pounds (0.5 kg) of fat.
Women in the vitamin D
group also gained 3.1 pounds (1.4 kg) more muscle than women in the placebo
group. However, there was no significant change in waist circumference or
overall weight (5).
similarly, a recent
review of 11 weight loss studies suggested that supplementation with
25,000-600,000 IU (625 to 15,000 mcg) of vitamin d per month over 1-12 months
could reduce BMI and waist circumference in overweight or obese patients.
However, these changes
are still small, and significant differences in overall weight are not noticed (6).
Despite these findings,
current research suggests that consuming more vitamin D has little effect on
weight gain or loss. Still, more research may be needed to differentiate
between body weight and body fat to properly assess this effect. （7, 8, 9, 10）。
Why do people who are overweight or obese generally have
lower vitamin d levels?
Currently, most
researchers believe that the lower vitamin d levels observed in overweight or
obese people may be explained by other factors.
For example, because
vitamin D is stored in adipose tissue, people with more body fat may need more
vitamin D to maintain blood levels similar to those of people with lower body
weight. （3, 4）。
People who are
overweight or obese may also spend less time outdoors or eat less vitamin
D-rich or vitamin-fortified foods (4).
Therefore, experts
suggest that overweight people may need 1.5 times more vitamin D than people
with a "normal" BMI to maintain similar blood levels, while obese
people may need 2-3 times more vitamin D. （4）。
Summary: People
who are overweight or obese generally have lower vitamin D levels compared to
people with BMI in the "normal" range. Still, there is limited
evidence that low vitamin D levels cause weight gain or make it more difficult
to lose body fat.
How to tell if you are vitamin d deficient
Over time, not getting
enough sun or eating small amounts of vitamin d-rich foods can cause you to be
deficient in vitamin d.
Signs and symptoms of vitamin d deficiency
Vitamin D deficiency
usually does not show significant symptoms unless the deficiency is severe, so
most people are unaware of their vitamin D deficiency until they have a blood
test. However, chronic severe deficiencies can lead to the following symptoms (1, 2):
- bone
pain or deformity
- childhood
diseases
- seizures
- muscle spasms
- abnormal teeth
- heart problems
If you notice any of the
above symptoms, be sure to discuss them with your healthcare provider to rule
out vitamin d deficiency.
People at the highest risk of vitamin d deficiency
Although vitamin d
deficiency affects anyone, some people may be at greater risk.
For example, people who
have undergone gastric bypass surgery may have a reduced ability to absorb
vitamin D from their diet, which may put them at a higher risk of vitamin D
deficiency. （1）。
This also seems true for
people with celiac disease, short bowel syndrome, inflammatory bowel disease
(IBD), cystic fibrosis, or chronic pancreatic insufficiency. （1）。
Older adults, as well as
those with darker skin tones or who rarely spendingspend time outdoors, may
also be at increased risk of vitamin D deficiency due to reduced ability to
produce enough vitamin D when exposed to sunlight alone. （1）。
In addition, vitamin D
deficiency is more common in obese people (1).
Finally, certain
prescription medications may accelerate the breakdown of vitamin D in the body,
which in turn may increase the risk of vitamin D deficiency. （1）。
Test your blood for vitamin d levels
If you suspect you may
have low vitamin d levels, consider testing your blood levels to rule out
vitamin d deficiency.
Optimal blood
concentrations tend to be in the 30–100 ng/mL range. Values below 20 ng/mL are
generally defined as mild deficiencies, and values below 10 ng/mL are
considered moderate deficiencies. Vitamin D levels below 5 ng/mL are considered
severe deficiencies (1, 11, 12).
Some health experts
recommend that you test your blood vitamin d levels twice a year—once in the
spring and once in the fall.
Doing so can help you
assess your current vitamin d levels associated with sun exposure and adjust
your vitamin d intake or supplement regimen accordingly.
Summary: People
who are deficient in vitamin D may experience a range of symptoms. If you
suspect that, your vitamin D levels may be low or fall into one of the
high-risk categories, consider having a blood test to rule out deficiencies.
Ways to increase vitamin d levels
There are many ways to
increase your vitamin d levels.
Solarization
When your skin is
exposed to ultraviolet B (UVB) sunlight, your body can produce this vitamin
from cholesterol (13).
According to experts,
exposing about 40% of the skin to the noonday sun for at least 20 minutes
without sunscreen is enough for most people to produce enough vitamin D(1).
However, people with
darker skin tones or who live above 35 degrees above and below the equator may
find that it is difficult to produce enough vitamin D from sunlight alone.
Smoke levels, cloud cover, altitude, and season are other influencing factors
to consider (1, 14, 15).
In addition, since
excessive ultraviolet radiation increases the risk of skin cancer, most
dermatologists warn against excessive exposure to the sun. （15）。
Diet and supplements
These reasons make it
important to make sure you include vitamin D-rich or fortified foods in your
diet. Some examples include fatty fish, mushrooms, fortified dairy or
plant-based milk, eggs, liver, and other meats (2).
The reference daily
intake (RDI) for vitamin D is currently set at 600 IU (15 mcg) per day for
adults and 800 IU (20 μg) per day for pregnant women (16).
However, some experts
believe that these recommendations are too low to maintain optimal vitamin D
levels (17).
If adequate blood
vitamin D levels cannot be maintained by sunlight and diet alone, supplements
of 800–4,000 IU (20–100 mcg) of vitamin D may be required (1, 18, 19).
keep in mind that
vitamin d is a fat-soluble vitamin, which means that taking too much for a long
time can cause it to accumulate in your tissues to levels that may be toxic.
Although the toxicity of
vitamin D is rare, long-term use of very high doses of vitamin D can lead to
dangerous side effects. The most common cause of vitamin D poisoning is
accidental overdose (20).
This can lead to nausea,
vomiting, muscle weakness, pain, loss of appetite, dehydration, brain
disorders, heart and kidney problems, and, in severe cases, death. （2）。
The best way to avoid
vitamin d toxicity is to check your blood vitamin d levels before and during
supplementation and work with your healthcare provider to adjust the dose
accordingly.
Summary: You can
increase your vitamin D levels by combining sun exposure, diet, and
supplementation. Regularly monitoring your blood vitamin D levels can help you
customize your supplement regimen and reduce your risk of vitamin D poisoning.
Conclusion
Vitamin d deficiency is
less likely to lead to weight gain. However, it can cause other health problems
or unpleasant symptoms, which are worth avoiding.
You can maintain
adequate vitamin d levels through limited sun exposure, a vitamin d-rich diet,
and taking vitamin d supplements.
If you suspect that your
vitamin d levels are poor, consider testing your blood levels to rule out
deficiencies. Doing so regularly can also help you adjust your supplement
regimen and reduce your risk of vitamin d poisoning.