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Running head: VITAMIN D RECOMMENDATIONS 1
Are Vitamin D Recommendations Too Low?
Lisa Hokanson
Dr. Kimberly Brodie
December 16, 2015
VITAMIN D RECOMMENDATIONS 2
Introduction
Vitamin D is an essential part of anyone’s diet. Many assume that with all of the
fortification in foods and the fact our bodies can create vitamin D from sunlight, we do not need
to be concerned about insufficiencies (Davison & Hanley, 2005). This is not the case as about
41% of the United States population is at a significantly low level of vitamin D known as a
vitamin D deficiency (Forrest & Stuhldreher, 2011). “Typically, the prevalence of low [vitamin
D] levels is approximately 36% in otherwise healthy young adults aged 18 to 29 years, 42% in
black women aged 15 to 49 years, 41% in outpatients aged 49 to 83 years, [and] up to 57% in
general medicine inpatients in the United States (Holick, Hossein-nezhad, & Spira, 2006).” Some
of the risk factors for a vitamin D deficiency include limited time spent outdoors, living in the
northern states where there is less sun exposure, obesity or pregnancy, and having darker or
thinner skin (Vitamin D Council, n.d.). At such a high rate of occurrence, it is essential to
determine why people are not getting enough vitamin D and whether or not the determined levels
of intake are at a suitable grade to meet the needs of the United States population.
According to the National Institutes of Health, people who have a vitamin D deficiency
have less than 30 nmol/L (nanomoles per liter) of vitamin D in their blood but that level could be
all the way up to 50 nmol/L depending on the person (U.S. Department of Health and Human
Services, 2014). The recommended level is around 50 nmol/L but it is suggested that we may
need even more than that as our ancient ancestors required levels around 115 nmol/L (Dijck-
Brouwer, Kema, Kuipers, Luxwolda, and Muskiet, 2012). Although our bodies have changed
since ancient times and adapted more to the lifestyles we now live, we still need vitamin D to
live functionally and the levels we are recommended to reach are likely much too low than
previously deemed appropriate.
VITAMIN D RECOMMENDATIONS 3
Purpose Statement
The current recommended level of vitamin D intake, as determined by the Centers for
Disease Control and Prevention (2012), is insufficient at 600 IU/day for adults and it needs to be
reevaluated for a level that will not result in such frequent deficiencies. Although it is very
difficult to get the recommended amount of vitamin D from just a healthy diet, supplementation
can fill the needed gaps if the right dose is prescribed or taken over the counter. This systematic
review aids in proving a lack of vitamin D, showing that there needs to be a reevaluation to
ensure people are getting the necessary intake to help eliminate preventable diseases as well as
demonstrate the many number of problems that result from a lack of vitamin D.
Research Question and Associated Hypotheses
In an effort to further understand the effects of vitamin D deficiencies, it is essential that
we evaluate and combine the studies that have already been completed to make connections and
find answers about the current levels of vitamin D intake. The research question investigated in
this systematic review is: Should the recommended vitamin D intake level for adults in the
United States be updated to a higher amount to prevent diseases and conditions that are a result
of a deficiency? The null hypothesis is that no change is necessary and the current level is
adequate. The alternative hypothesis reasons that a change in recommendation is preferable and
can help reduce serious diseases linked to a vitamin D deficiency.
Potential Significance
As vitamin D is studied further and we gain more understanding of its benefits, it has
become evident that without this vitamin, a greater number of people are suffering from major
chronic diseases and conditions. Some of these include kidney diseases, osteomalacia, psoriasis,
VITAMIN D RECOMMENDATIONS 4
diabetes, and heart disease (Mayo Clinic, 2013). While much of the research regarding vitamin
D has been inconclusive and the actual effect it has on the brain is still being studied (Eyles,
Hewison, et al, 2005), it is affirmed that deficiencies of this vitamin in our diet presents a higher
risk of several extremely serious diseases such as Multiple Sclerosis (MS) and HIV/AIDS
(Vitamin D Council, n.d. a). In the case of Multiple Sclerosis, vitamin D plays a part in
connecting receptors in the immune and nervous systems as well as preventing inflammation in
cells (Vitamin D Council, 2014). Researchers are getting close to finding a definitive
relationship between vitamin D intake and the development of MS but it has already been
suggested based on research that children high in vitamin D are less likely to develop this
condition. That is a significant enough reason to ensure people are getting adequate vitamin D
without even considering of all the other diseases that are also linked to this vitamin. With
vitamin D deficiencies at 41% of the US adult population, it is growing to epidemic proportions
and unfortunately, the “correct” level of intake is potentially incorrect. This systematic review
has the potential to redefine the nutritional standard for this vitamin by revealing the prevalence
and impact of vitamin D deficiency on the US population.
Search Strategy
To find the most appropriate articles and studies for this review, two search engines were
used; EBSCOhost and PubMed. These engines were accessed in September of 2015 with only
articles dating back to the year 2005 used for this review. The terms used for finding the best
articles included vitamin D deficiencies, vitamin D deficiency, United States, and adults;
excluding children. These searches resulted in thousands of studies but they were easily deemed
relevant or not based on if they were studies and reviews (which were used) versus other less
relevant options such as results reviews or magazine articles from other countries.
VITAMIN D RECOMMENDATIONS 5
Theoretical Foundation
The Theory of Planned Behavior is a theory that was developed in 1980 to explain what a
person’s intention is behind a behavior (Boston University of Public Health, 2013). It was
developed by Martin Fishbein and Icek Ajzen to explain the connection between attitude and
behavior as it seemed behavior was often determined by preconceived intentions that were
regularly influenced by others (University of Twente, n.d.). The theory connects behavioral
beliefs, normative beliefs, and control beliefs to determine someone’s attitude, social influence,
and perceived control of an action. Essentially, it finds the reason why someone does or does not
participate in a healthy decision and works to change specific aspects of the person’s thinking to
make for a more positive behavior. As an example, a study was recently published that found
people in Korea had a higher intent to continue working out at a gym if they were participating in
a sport that required other participants (Park & Song, 2015). The influence of other’s actions in
this study changed the intent of the subject’s actions thereby changing their behavior.
In regards to this systematic review, this theory seemed to be the most appropriate fit in
understanding the effects of vitamin D deficiencies and how it can impact the general public.
The majority of those who suffer from vitamin D deficiencies are not aware of this problem and
do not know what it can do to hinder one’s health. The Theory of Planned Behavior can analyze
why people do and do not get enough vitamin D in their diets and what factors lead them to
believe they do not need to be concerned about this vitamin. Also, it can be used to help
understand why current recommended levels are set at the suggested rate and whether or not it is
still an appropriate level for our society.
VITAMIN D RECOMMENDATIONS 6
Literature Review
There are many physiological reasons why vitamin D is necessary and there have been
studies conducted to find how it connects with diseases. Vitamin D works closely with the brain
and the communication of cells and is also known to change the expression of certain genes to
avoid diseases (Holick, Hossein-nezhad, Spira, 2013). Although this is a relatively new subject
in the field of public health, vitamin D has many great qualities and is very important to
replenish.
To combat the problems that are arising with vitamin D deficiencies, it seems necessary
to reevaluate the recommended dietary levels and how people are getting this critical nutrient.
HIV patients are known to have this deficiency which can be easily altered if doctors screened
them at appointments (Brooks & Bush, et al, 2011). Also, people of certain races and ethnicities
are genetically more likely to have vitamin D deficiencies and therefore have greater health
problems as a result (Davison & Hanley, 2005). In a research trial where one group took the
recommended amount of vitamin D daily and another took double the recommended amount, the
second group was at a much lower risk of falls and breaks along with greater muscle mass and a
reduction in risk of cancers (Bischoff-Ferrari & Boucher et al, 2007). With these clear
improvements in health due to an increase in vitamin D intake, it should not be a question as to
whether or not the recommendations need to be reexamined. One of the next steps our society
needs to make in disease prevention is an increase in vitamin D intake.
Unfortunately, there are only a few studies that have been completed determining the
value of vitamin D and its effect on health. The struggle is to understand exactly how this
vitamin plays a role in the brain and scientists are unable to fully track its progression. There is
research which suggests the enzymes that make up vitamin D functions as cell receptors and
VITAMIN D RECOMMENDATIONS 7
helps aid in communication between cells and the brain (Yetley, 2008). If there is not a sufficient
supply of vitamin D, these necessary processes are not performing correctly which results in
several diseases and conditions. This explains why inadequate levels of vitamin D can be
detrimental to a person’s health.
Methods
Vitamin D deficiencies are a significant problem in the United States and much of this
has to do with the unclear daily recommended intake. The Centers for Disease Control and
Prevention (2012) currently has the level at 600 IU a day but this is not enough for most and it is
difficult to get that much from food alone. By doing a systematic review, previous studies of
vitamin D and its effects on the US adult population were combined to determine if the
deficiency is a result of inadequate intake recommendations. There are many studies linking a
vitamin D deficiency with chronic diseases and conditions but by bringing them together, it is
determined whether or not our society needs to enact a higher recommendation to help lessen the
incidence of these diseases. This review is focused on adults in the United States who have a
vitamin D deficiency as well as studies on the effects of vitamin D and the recommended intake
level.
Inclusion and Exclusion Criteria
The two main search engines used for this systematic review were Academic Search
Premier and PubMed. There were other articles added later as found and deemed appropriate but
these were the two search engines used. The studies found were those published in 2005 or later
and involving adults, age 18-65, who were vitamin D deficient in the United States and who did
not have significant medical conditions. The elderly, children, and women who were pregnant
were all excluded as they generally require more vitamin intake than the general population (see
VITAMIN D RECOMMENDATIONS 8
Table 1 below). The purpose of the review is to determine if the vitamin D recommendations
should be changed for the general population and the elderly, children, and pregnant women
have different and much more specific needs than the rest of the public so it seems appropriate to
exclude them from the review.
Table 1
Inclusion and Exclusion Criteria
Inclusion Criteria Exclusion Criteria
Vitamin D Deficiency “Older” or “Elderly”
adults
United States Children
Adults Chronic conditions
Since 2005 Pregnant women
Data Analysis Plan
To keep all of the information organized, Endnote X7 software was used which allows
for all selected articles from different databases to be compiled into one system. This enabled
the elimination of all duplicate articles and allowed for further filtering through the remaining
articles including the deletion of those not meeting the inclusion criteria. For example, there
were many studies initially considered that had subjects who were from foreign countries which
was not within the scope of the review. This software made it possible to go through the articles
multiple times to only have the most relevant articles used in the review. Figure 1 shows the
elimination process below.
VITAMIN D RECOMMENDATIONS 9
Data Collection
Figure 1. Flowchart of article selection process.
In order to find the most beneficial articles to defend this systematic review, it became
necessary to do extensive filtering of the articles that were found during the original research
process. Although 62 studies were found to be relevant to the review, upon further examination,
only 12 studies were deemed appropriate for the results section based on the amount of data
Full-text articles excluded
for relevancy (n = 175)
Records identified through
database searching (n = 1463)
Additional records identified
through other sources (n = 9)
Records after duplicates removed
(n = 1409)
Records screened
(n = 1409)
Records excluded
(n = 1172)
Full-text articles assessed
for eligibility (n = 237)
Qualitative
Studies (n = 32)
Studies included in
systematic review (n = 62)
Quantitative
Studies (n=30)
VITAMIN D RECOMMENDATIONS 10
available and the clarity of the methods and participant characteristics. Some of the studies
included in the group of 62 articles were more appropriate for the literature review or
introduction as they had good information but not sufficient data to support the purpose of the
review.
Results
Each of the 12 included articles are listed in the table below to provide a brief summary
of their study along with the intervention and outcomes. The actual data is listed in Table 3.
Additionally, this table provides a quality score which rates each article based on a set of
questions that shows how they rank in regards to clarity, focus, and limitations of the article.
This ensures that only the best articles are used because they have the information necessary to
be considered high quality.
Table 2
Characteristics of Included Studies
Study
(Authors’
name)
Setting Study
Design
n Population Intervention Primary
Outcomes
Quality
Score
Alvarez,
et al.
Emory
University
Campus
Randomized,
double-blind,
placebo-
controlled trial
28 Healthy adults
between 18-
65 years old
Each group
(experimental and
placebo) were given
5 identical pills with
experimental having
50,000 IU of vitamin
D. Periodic blood
draws determined
effectiveness of large
vitamin D doses
Large doses
were
effective in
preventing
seasonal
problems
but wore off
after 3
months
2
VITAMIN D RECOMMENDATIONS 11
Barker, et
al.
LabCorp
facilities and
Retrospective
cross-sectional
study
743 Employees, or
friends or
family of
employees, of
USANA
Health
Sciences, a
manufacturer
of nutritional
supplement
Blood samples were
collected to
determine vitamin D
levels then surveys
were completed to
find sources of the
vitamin
Vitamin D
supplementa
tion was the
greatest
predictor of
vitamin D
status
5
Liu, et al. Using the
The 2007–
2010
National
Health and
Nutrition
Examination
Survey
Cross-Sectional 9719 Adults age
19+
Used previous data to
determine if vitamin
D levels are
dependent on
income,
race/ethnicity, or
gender
Category
with most
vitamin D in
their diet
was high-
income
white men
and lowest
was middle-
income
black men
4
Burnett-
Bowie, et
al.
Participants
were found
through
mailings and
newspaper/
Internet ads
Cross-Sectional 634 Volunteers
age 18-50
Participants were
each visited and a
blood sample was
taken. This was
immediately studied
for the vitamin D
level and they
answered
demographic and
habit-related
questions
64% of
participants
had levels
less than 30
ng/mL
4
Caporaso
, et al.
Orange
County, CA
Cohort 151 Residents of
Orange
County
between ages
18-90
Blood samples were
taken from all
participants to
measure vitamin D
level. Demographics
were also recorded.
19.2% of
participants
had low
vitamin D
levels
5
Connett,
et al.
Lung Health
Study
Nested,
matched case-
control study
196 Smokers with
decreased
lung function
Used data from three
previous studies to
find vitamin D status
among participants
31% were
vitamin D
defficient
5
VITAMIN D RECOMMENDATIONS 12
Ameri, et
al.
California
laboratories
Randomized,
Placebo-
controlled,
double-blind
study
105 Healthy adults
age 18-84
Participants either
took vitamin D
supplements or drank
fortified orange juice
to determine which
was more effective
There was
no
significant
difference
between
those who
took
supplements
and those
who drank
fortified
orange juice
3
Booth, et
al.
Established
research
center for
Framingham
Study
Cohort Study 3890 Used results
from
Framingham
Heart Study
Blood samples were
taken and studied for
vitamin D level.
Additionally, the
participants were also
measured for adipose
and visceral fat levels
along with BMI
measurements.
Obesity is
linked to a
higher rate
of vitamin D
deficiency
5
Camargo,
et al.
National
survey data
Cross-sectional 18883
and
13369
Those willing
to take the
survey in the
US
population
Two National Health
and Nutrition
Examination Surveys
were compared for
vitamin D national
levels.
The US has
seen a
significant
decrease in
vitamin D
levels since
the surveys
conducted
1988-1994.
The mean
level
dropped
6ng/mL
5
Camargo,
et al.
National
survey data
Cross-sectional 15,148 National
survey
participants
Two NHANES
studies were
compared to
determine if physical
activity helped with
vitamin D levels.
Surveys and in-
person interviews
were conducted.
More
activity
resulted in
higher
vitamin D
levels
4
VITAMIN D RECOMMENDATIONS 13
Alberts,
et al.
Tucson and
Phoenix
Cross-Sectional 619 Participants in
a colorectal
adenoma
prevention
study
Blood samples were
taken and
questionnaires were
answered about
participants’ habits
A significant
number of
adults in
Arizona,
where
people are
exposed to
more sun,
were
deficient in
vitamin D.
This was
especially
true for
blacks and
Hispanics.
4
Aloia, et
al.
Long Island Randomized,
double-blind,
placebo-
controlled
138 Healthy white
and black
adults age 18-
65
Different original
levels of vitamin D
determined the
category and amount
each subject was
given to raise to an
ideal level in six
months
People with
levels above
55 nmol/L
need 3800
IU to reach
an optimal
state and
those below
55 nmol/L
need 5000
IU
5
The information included in Table 2 supports the purpose of the systematic review by
providing studies that involved American adults who were relatively healthy. All of the articles
that were included met the inclusion criteria in that they focused on a significant number of
adults in the United States that did not suffer from extensive medical conditions. There were
many studies included in the searches that had subjects who had serious diseases or conditions
that were linked to vitamin D deficiencies but these were not included because the purpose was
to create a systematic review that was more easily transferrable to the general population. The
VITAMIN D RECOMMENDATIONS 14
majority of the studies also had a higher quality score and included a significant number of
subjects which made the data more universal.
Table 3: Results of Included Studies
Author Quality
Score
Intervention Measures Results Statistically
Significant
Alvarez,
et al.
2 Each group
(experimental and
placebo) were given 5
identical pills with
experimental having
50,000 IU of vitamin
D. Periodic blood
draws determined
effectiveness of large
vitamin D doses
Mean plasma
25(OH)D
concentration
Plasma 25(OH)D
concentrations
improved for
experimental group
with increase of
24.69 ng/ml for five
days and only 1.37
ng/ml for placebo
group. No significant
changes for 90 or 365
days
P<0.001
Barker, et
al.
5 Blood samples were
collected to determine
vitamin D levels then
surveys were
completed to find
sources of the vitamin
Vitamin D
level, diet,
supplement
usage, latitude
of residence,
ethnicity, age,
and BMI
Depending on the
current level of
vitamin D, people are
recommended either
3800 IU or 5000 IU
to get their level back
within reason.
P<.05 –
Statistically
significant
depending
on season
Liu, et al. 4 Used previous data to
determine if vitamin D
levels are dependent
on income,
race/ethnicity, or
gender
Vitamin D
concentrations
and participant
characteristics
Higher vitamin D
was associated with
higher income, non-
Hispanic white
people. Women took
more supplements.
P≤.05
Burnett-
Bowie, et
al.
4 Participants were each
visited and a blood
sample was taken.
This was immediately
studied for the vitamin
D level and they
answered
demographic and
habit-related questions
Vitamin D
levels
Lower vitamin D
level predictors:
male, black or Asian
race, lack of
multivitamin use.
Seasonal variation
prevalent in all who
didn’t take a
supplement. Low
levels associated with
parathyroid and
skeletal diseases.
P<0.1
Caporaso,
et al.
5 Blood samples were
taken from all
participants to
measure vitamin D
Vitamin D
concentrations
19.2% of Orange
County residents
were deficient
(<30pg/ml)
No p-value
recorded
VITAMIN D RECOMMENDATIONS 15
level. Demographics
were also recorded.
Connett,
et al.
5 Used data from three
previous studies to
find vitamin D status
among participants
Vitamin D
levels
35% vitamin D
insufficient (≥ 20
ng/ml but < 30
ng/ml) and 31%
deficient (<20 ng/ml),
34% sufficient (≥ 30
ng/ml), and 7%
severely deficient
(≤10 ng/ml).
p<0.001
p=0.54
Ameri, et
al.
3 Participants either
took vitamin D
supplements or drank
fortified orange juice
to determine which
was more effective
Vitamin D
levels
Fortified orange juice
is just as effective as
supplementation at
providing vitamin D.
No
significant
difference
P = .084
P > .1
P = .82
Booth, et
al.
5 Blood samples were
taken and studied for
vitamin D level.
Additionally, the
participants were also
measured for adipose
and visceral fat levels
along with BMI
measurements.
Vitamin D
levels and fat
indexes
Lower vitamin D
associated with:
Higher BMI,
Higher visceral and
subcutaneous adipose
tissues,
Insulin resistance
P < 0.005
P = 0.016
P < 0.0001
Camargo,
et al.
5 Two National Health
and Nutrition
Examination Surveys
were compared for
vitamin D national
levels.
Vitamin D
levels and
recreational
activities
No p-value
recorded
Camargo,
et al.
4 Two NHANES studies
were compared to
determine if physical
activity helped with
vitamin D levels.
Surveys and in-person
interviews were
conducted.
Comparison of
two studies
measuring
25(OH)D
concentrations
Mean level = 30
ng/ml (1988-1994)
Mean level = 24
ng/ml (2001-2004).
Levels <10ng/ml
increased 2% to 6%.
Levels ≥30 ng/ml
decreased 45% to
23%
p = 0.0005
Alberts,
et al.
4 Blood samples were
taken and
questionnaires were
answered about
participants’ habits
Serum
25(OH)D
concentrations
25% of participants
were deficient, 22.5%
= 30 ng/ml,
25.4% <20 ng/ml,
2% <10 ng/ml,
Black (55.5%) and
Hispanic (37.6%)
<20 ng/ml with
Non-Hispanic white
P value <
0.05
VITAMIN D RECOMMENDATIONS 16
at 22.7%
Aloia, et
al.
5 Different original
levels of vitamin D
determined the
category and amount
each subject was given
to raise to an ideal
level in six months
Serum
25(OH)D
concentrations
P < 0.05
All of these studies measured vitamin D levels and what potential influences and factors
cause deficiencies. The studies suggest that vitamin D levels are much too low for most
Americans regardless of location, even in Arizona where the sun is out much more than other
places (Alberts, et al, 2008). The table also shows that certain population groups are at a higher
risk of deficiency such as those of Black or Hispanic race (Liu, et al, 2014). One of the most
striking studies was done in 2009 (Camargo, et al) when researchers compared national data for
two National Health and Nutrition Examination Surveys comparing vitamin D levels of 1988-
1994 to levels of 2001-2004. They found that there was an average decrease of 6 ng/ml which
puts the population significantly below an adequate level. Most of the other articles included
provided support to this theory by recording the 25(OH)D concentrations of the participants and
discovering that a large number of participants were deficient; 35% (Connett, et al, 2011), 25%
(Alberts et al, 2008), and even 19.2% of Orange County residents (Caporaso, et al, 2011).
Figure 2: Results of systematic analysis.
There were no studies that suggested there
was no correlation between vitamin D
deficiencies and diseases. There was no
contradictory data; just a significant lack of this
essential vitamin.
All of the studies reported a significantly high
level of vitamin D deficiency among various
populations. They complemented each other
in their purpose and goal of proving that the
United States population is in drastic need of
additional supplementation of this essential
vitamin.
VITAMIN D RECOMMENDATIONS 17
Discussion
Based on the evidence provided in the results, it is clear that adults in the United States
are at a critical state of vitamin D deficiency. With one study claiming 64% of their participants
being deficient (Burnett-Bowie, et al, 2012), 31% in another study (Connett, et al, 2011), and
19.2% of those in Orange County (Caporaso, et al, 2011), it is evident that something needs to
change because people are not getting this essential vitamin. It is not enough that they get
exposure to sunlight or eat foods high in vitamin D, they must also take a supplement in order to
achieve the highest potential intake and avoid major diseases that are being linked to a vitamin D
deficiency. This is undoubtedly a need that needs to be more adamantly addressed and explored
by the government in order to recommend a higher dosage of the vitamin.
Based on the data above, vitamin D deficiencies are very common and occur frequently
among those who are obese (Booth, et al, 2010) as well as men who are middle-income and of
African-American or Hispanic race (Liu, et al, 2014). Additionally, there has been a drop in the
average vitamin D level among the United States from 30 ng/mL to 24 ng/mL from the years
1988-1994 to 2001-2004 (Camargo, et al, 2009). The ideal level is at least 30 ng/mL but with a
drop of 6 ng/mL within 10-16 years, that is a 20% difference which puts a large portion of U.S.
adults at serious risk of major diseases and conditions. This is unacceptable and warrants a
professional reevaluation of how to change this trend.
Theoretical Implications
In order for people to change their actions to a higher intake of vitamin D, they must be
aware of their risk and accept that the change is beneficial and crucial. The Theory of Planned
Behavior is based on a person’s preconceived intentions toward a behavior so in order for them
to participate, they must first understand that they are potentially in a high risk group. By
VITAMIN D RECOMMENDATIONS 18
understanding that a significant portion of the adults in the United States are at a high risk of a
deficiency, others can take the research included in this systematic review and find ways to
influence their community in participating in interventions that include high intakes of vitamin D
supplementation. The findings above provide a starting place for other public health educators to
develop interventions that can affect a person’s perceptions and eventually behavior in regards to
additional vitamin D supplementation. The data is a solid foundation that vitamin D deficiencies
are a growing problem within the United States.
Because the data in this review is based on separately conducted research studies, it is
essential that it be used as a support for a higher intervention and as a suggestion that
recommended supplementation regulations be reviewed. It should not be used as a standard for
what a new recommended level should be because no research studies were actually conducted.
It is suggested that it be used as a resource for the current state of vitamin D deficiencies for
adults within the United States.
Limitations
There are several potential limitations to this systematic review for consideration.
Although not every limitation can be listed, some include selection bias, database limitations,
language availability, and human error. Selection bias is a potentially high occurring limitation
considering several thousand articles were originally retrieved when searching for data but since
they cannot all be included in the study, some needed to be eliminated quickly. This possibly
resulted in articles being eliminated that could have supported the overall purpose of the study.
Additionally, only two databases were used in the study, both of which only included studies
written in English, which could have excluded significant studies that were in a different
language or not included in those particular databases. Lastly, human error could have played a
VITAMIN D RECOMMENDATIONS 19
significant role in any part of the study. This study was created on a time limit so it is possible
that significant studies were missed or mistakenly deleted. Because of the listed limitations,
there is the possibility that the review is not as complete as it could be and that there are
confounding factors between the studies included. This may change the overall results but it is
believed that it would only be a minor difference.
As for specific studies, two of the studies included did not record p-values. This makes it
difficult to determine if the data reported is statistically significant. There is also the issue of the
quality scores as one study was included that had a score of 2 and the others had higher ratings
but the questions used to determine the score were very easily biased based on the researcher’s
evaluation of the study components. It is difficult to be sure that those were accurate scores or
that those eliminated based on quality scores were appropriately excluded.
Recommendations
Based on the research provided, vitamin D should play a greater role in our healthcare
requirements and concerns because of the benefits it provides and the clearly evident deficiency
we are suffering. With a decline of average intake from 30 ng/mL to 24 ng/mL in just 16 years
(Camargo, Ginde, & Liu, 2009), the adults of the United States are in need of continuing
guidance and education that will increase intake over time. There are many reasons why people
are not getting enough vitamin D including more indoor activities, less physical exertion, and
more processed foods. These issues need to be addressed by the appropriate parties to ensure the
level does not continue dropping. Further decrease will continue to facilitate additional chronic
health problems and therefore an overall decline in the United States’ health status.
As is evident from this review and the supporting data, there is a significant need for the
adult population of the United States to get more vitamin D through either their dietary intake or
VITAMIN D RECOMMENDATIONS 20
additional supplementation. Unfortunately, there is not an adequate level of intake established
by government or public health officials because there has not been enough research to
determine how essential vitamin D is to the body and how fully it interacts with the brain and
other systems. Researchers are on the cusp of understanding its effects but further research could
solidify that the general population needs to make it a greater priority and find ways to add more
of the vitamin into their everyday diet. After finding those answers, more research needs to be
done to determine the optimal level of intake based on the ideal effects vitamin D can offer.
Implications for Social Change
Encouraging an adequate intake of vitamin D could potentially save millions of dollars
on healthcare costs annually as people take control of their preventative care and lessen their risk
of getting diseases related to a vitamin D deficiency. As is clear from the results, the adult
population in the United States needs a higher intake of this essential vitamin and there are many
positive benefits that can make for an overall healthier public. By starting now and educating on
the importance of supplementation, the next generation can grow to understand the mistakes of
their predecessors and understand that they need to be more aware of their vitamin D levels. In
the age of quick results and immediate satisfaction, it is important to take a step back and
understand the need to take care of long-term potential health issues and the future generations
may be in the best position to start anew and begin taking control of their health.
VITAMIN D RECOMMENDATIONS 21
References
Alberts, D. S., Foote, J. A., Green S. B., Hollis, B. W., Jacobs, E. T., Martinez, M. E., Yu, Z.
(2008). Vitamin D insufficiency in southern Arizona. The American Journal of Clinical
Nutrition. 87(3); 606-613. Retrieved from
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4113473/
Aloia, J. F., Dimaano, R., Li-Ng, M., Mikhail, M., Patel, M., Pollack, S. Talwar, S. A., Yeh, J. K.
(2008). Vitamin D intake to attain a desired serum 25-hydroxyvitamin D concentration.
The American Journal of Clinical Nutrition. 87(6): 1952-1958. Retrieved from
http://ajcn.nutrition.org/content/87/6/1952.long
Alvarez, J. A., Binongo, J. N., Kearns, M. D., Lodin, D., Tangpricha, V., Watson, D., Ziegler, T.
R. (2015). The effect of a single, large bolus of vitamin D in healthy adults over the
winter and following year: a randomized, double-blind, placebo-controlled trial.
European Journal of Clinical Nutrition. 69(2): 193-197. Retrieved from
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4318716/
Ameri, A., Biancuzzo, R. M., Bibuld, D., Cai, M. H., Chen T. C., Holick, M. F., Klein, E. K.,
Reitz, R., Salameh, W., Winter, M. R., Young, A. (2010). Fortification of orange juice
with vitamin D(2) or vitamin D(3) is as effective as an oral supplement in maintaining
vitamin D status in adults. The American Journal of Clinical Nutrition. 91(6): 1621-1626.
Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2869510/
Barker, T., Cuomo, J., Dern, A., Dixon, B. M., Helland, T., Levy, M. A., McKinnon, T.,
Robertson, J., Wood, T. (2015). Predictors of vitamin D status in subjects that consume a
vitamin D supplement. European Journal of Clinical Nutrition. 69(1): 84-89. Retrieved
from http://www.nature.com/ejcn/journal/v69/n1/full/ejcn2014133a.html
VITAMIN D RECOMMENDATIONS 22
Bischoff-Ferrari, H., Boucher, B. J., Dawson-Hughes, B., Garland, C. F., Heaney, R. P., Holick,
M. F., Hollis, B. W., Lamberg-Allardt, C., McGrath, J. J., Norman, A. W., Scragg, R.,
Vieth, R., Whiting, S. J., Willett, W. C., Zittermann, A. (2007). The urgent need to
recommend an intake of vitamin D that is effective. American Journal for Clinical
Nutrition. 85(3): 649-650. Retrieved from http://ajcn.nutrition.org/content/85/3/649.short
Boston University School of Public Health. (2013). The theory of planned behavior. Retrieved
from http://sphweb.bumc.bu.edu/otlt/MPH-Modules/SB/SB721-Models/SB721-
Models3.html
Booth, S. L., Cheng, S., Fox, C. S., Hoffman, U., Jacques, P. F., Keyes, M. J., Larson, M. G.,
Massaro, J. M., McCabe, E. L., O’Donnell, C. J., Robins, S. J., Vasan, R. S., Wang, T. J.,
Wolf, M. (2010). Adiposity, cardiometabolic risk, and vitamin D status: the Framingham
Heart Study. Diabetes. 59(1): 242-248. Retrieved from
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2797928/
Brooks, J. T., Bush, T., Dao, C. N., Johnson, C., Overton, E. T., Pals, S. L., Patel, P., Rhame, F.
(2011). Low vitamin d among HIV-infected adults: prevalence of and risk factors for low
vitamin d levels in a cohort of HIV-infected adults and comparison to prevalence among
adults in the US general population. Clinical Infectious Diseases. 52(3). 396-405.
Retrieved from
http://web.a.ebscohost.com.vproxy.cune.edu/ehost/detail/detail?vid=8&sid=ebd9973f-
7427-4338-810e-
202e2259b44f%40sessionmgr4004&hid=4112&bdata=JnNpdGU9ZWhvc3QtbGl2ZQ%3
d%3d#AN=78118554&db=aph
VITAMIN D RECOMMENDATIONS 23
Burnett-Bowie, S. M., Finkelstein, J. S., Henao, M. P., Mitchell, D. M. (2012). Prevalence and
predictors of vitamin D deficiency in healthy adults. Endocrine Practice. 18(6): 914-923.
Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3755751/
Camargo, C. A. Jr., Ginde, A. A., Liu, M. C. (2009). Demographic differences and trends of
vitamin D insufficiency in the US population, 1988-2004. Archives of Internal Medicine.
169(6): 626-632. Retrieved from
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3447083/
Camargo, C. A. Jr., Scragg, R. (2008). Frequency of leisure-time physical activity and serum 25-
hydroxyvitamin D levels in the US population: results from the Third National Health
and Nutrition Examination Survey. American Journal of Epidemiology. 168(6): 577-586.
Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2727193/
Caporaso, F., Dror, A., Frisch, F., Holland, D., Horani, M. (2011). Prevalence of vitamin D3
deficiency in orange county residents. Journal of Community Health. 36(5): 760-764.
Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/21327501
Centers for Disease Control and Prevention. (2012). Second national report on biochemical
indicators of diet and nutrition in the U.S. population. 172-192. Retrieved from
http://www.cdc.gov/nutritionreport/pdf/Nutrition_Book_complete508_final.pdf
Connett, J. E., Kinisaki, K. M., Niewoehner, D. E., Singh, R. J. (2011). Vitamin D status and
longitudinal lung function decline in the Lung Health Study. The European Respiratory
Journal. 37(2): 238-243. Retrieved from
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3070416/
Davison, D. A., Hanley, D. A. (2005). Vitamin d insufficiency in North America. The Journal of
Nutrition. 135(2): 332-337. Retrieved from http://jn.nutrition.org/content/135/2/332.full
VITAMIN D RECOMMENDATIONS 24
Dijck-Brouwer, D. A., Kema, I. P., Kuipers, R. S., Luxwolda, M. F., Muskiet, F. A. (2012).
Traditionally living populations in East Africa have a mean serum 25-hydroxyvitamin D
concentration of 115 nmol/l. British Journal of Nutrition. 108(9): 1557-61. Retrieved
from http://www.ncbi.nlm.nih.gov/pubmed/22264449
Eyles, D. W., Hewison, M., Kinobe, R., McGrath, J. J., Smith, S. (2005). Distribution of the
vitamin D receptor and 1 alpha-hydroxylase in human brain. Journal of Chemical
Neuroanatomy. 29(1): 21-30. Retrieved from
http://www.ncbi.nlm.nih.gov/pubmed/15589699
Forrest, K. Y. Z, Stuhldreher, W. L. (2011). Prevalence and correlates of vitamin d deficiency in
US adults. Nutrition Research. 31(1): 48-54. Retrieved from
http://web.a.ebscohost.com.vproxy.cune.edu/ehost/detail/detail?vid=4&sid=ebd9973f-
7427-4338-810e-
202e2259b44f%40sessionmgr4004&hid=4112&bdata=JnNpdGU9ZWhvc3QtbGl2ZQ%3
d%3d#AN=57872809&db=aph
Holick, M. F., Hossein-nezhad, A., Spira, A. (2006). High prevalence of vitamin d inadequacy
and implications for health. Mayo Clinic Proceedings. 81(3). 353-373. Retrieved from
http://www.mayoclinicproceedings.org/article/S0025-6196(11)61465-
1/fulltext?mobileUi=0
Holick, M. F., Hossein-nezhad, A., Spira, A. (2013) Influence of vitamin d status and vitamin d3
supplementation on genome wide expression of white blood cells: a randomized double-
blind clinical trial. PLoS ONE. 8(3). Retrieved from
http://web.a.ebscohost.com.vproxy.cune.edu/ehost/pdfviewer/pdfviewer?sid=b87133e6-
836b-4271-915e-49b49e10e46c%40sessionmgr4001&vid=9&hid=4112
VITAMIN D RECOMMENDATIONS 25
Liu, Y., Moore, C. E., Radcliffe, J. D. (2014). Vitamin D intakes of adults differ by income,
gender and race/ethnicity in the U.S.A., 2007 to 2010. Public Health Nutrition. 17(4):
756-763. Retrieved from
http://journals.cambridge.org/download.php?file=%2FPHN%2FPHN17_04%2FS136898
0013002929a.pdf&code=085cf59df4f3484683c2e95bce65491e
Mayo Clinic. (2014). Vitamin D: Evidence. Retrieved from http://www.mayoclinic.org/drugs-
supplements/vitamin-d/evidence/hrb-20060400
Park, H. S., Song, C. (2015). Testing intention to continue exercising at fitness and sports centers
with the theory of planned behavior. Social Behavior & Personality: An International
Journal. 43(4): 641-648. Retrieved from
http://web.a.ebscohost.com.vproxy.cune.edu/ehost/pdfviewer/pdfviewer?sid=935f543c-
06ed-40fc-96c2-e531c6181acf%40sessionmgr4002&vid=4&hid=4112
University of Twente. (n.d.). Theory of planned behavior/reasoned action. Retrieved from
https://www.utwente.nl/cw/theorieenoverzicht/Theory%20Clusters/Health%20Communi
cation/theory_planned_behavior/
U.S. Department of Health and Human Services. (2014). Vitamin D: fact sheet for health
professionals. Retrieved from https://ods.od.nih.gov/factsheets/VitaminD-
HealthProfessional/
Vitamin D Council. (2014). Multiple sclerosis. Retrieved from
https://www.vitamindcouncil.org/health-conditions/multiple-sclerosis/
Vitamin D Council. (n.d.). Am I deficient in vitamin D? Retrieved from
https://www.vitamindcouncil.org/about-vitamin-d/am-i-deficient-in-vitamin-d/
VITAMIN D RECOMMENDATIONS 26
Vitamin D Council. (n.d. a). Health conditions. Retrieved from
https://www.vitamindcouncil.org/health-conditions/
Yetley, E. A. (2008). Assessing the vitamin D status of the US population. The American
Journal of Clinical Nutrition. 88(20): 5585-5645. Retrieved from
http://ajcn.nutrition.org/content/88/2/558S.long
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