Are Vitamin D Recommendations Too Low? Lisa Hokanson. Dr. Kimberly Brodie

Transcription

1 Running head: VITAMIN D RECOMMENDATIONS 1 Are Vitamin D Recommendations Too Low? Lisa Hokanson Dr. Kimberly Brodie December 16, 2015

2 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.

3 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,

4 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.

5 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.

6 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

7 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

8 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 Vitamin D Deficiency United States Adults Since 2005 Exclusion Criteria Older or Elderly adults Children Chronic conditions 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.

9 VITAMIN D RECOMMENDATIONS 9 Data Collection 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) Full-text articles excluded for relevancy (n = 175) Studies included in systematic review (n = 62) Qualitative Studies (n = 32) Quantitative Studies (n=30) 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

10 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, placebocontrolled trial 28 Healthy adults between 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

11 VITAMIN D RECOMMENDATIONS 11 Barker, et al. LabCorp facilities and Liu, et al. Using the The National Health and Nutrition Examination Survey Category with most vitamin D in their diet was highincome white men and lowest was middleincome black men 64% of participants had levels less than 30 ng/ml Burnett- Bowie, et al. Caporaso, et al. Connett, et al. Participants were found through mailings and newspaper/ Internet ads Orange County, CA Lung Health Study Retrospective cross-sectional study Cross-Sectional 9719 Cross-Sectional Employees, or friends or family of employees, of USANA Health Sciences, a manufacturer of nutritional supplement Adults age 19+ Volunteers age Cohort 151 Residents of Orange County between ages Nested, matched casecontrol study 196 Smokers with decreased lung function Blood samples were collected to determine vitamin D levels then surveys were completed to find sources of the vitamin Used previous data to determine if vitamin D levels are dependent on income, race/ethnicity, or gender 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 Blood samples were taken from all participants to measure vitamin D level. Demographics were also recorded. Used data from three previous studies to find vitamin D status among participants Vitamin D supplementa tion was the greatest predictor of vitamin D status 19.2% of participants had low vitamin D levels 31% were vitamin D defficient

12 VITAMIN D RECOMMENDATIONS 12 Ameri, et al. Booth, et al. Camargo, et al. Camargo, et al. California laboratories Established research center for Framingham Study National survey data National survey data Randomized, Placebocontrolled, double-blind study 105 Healthy adults age Cohort Study 3890 Used results from Framingham Heart Study Cross-sectional and Those willing to take the survey in the US population Cross-sectional 15,148 National survey participants 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 Blood samples were Obesity is taken and studied for linked to a vitamin D level. higher rate Additionally, the of vitamin D participants were also deficiency measured for adipose and visceral fat levels along with BMI measurements. Two National Health and Nutrition Examination Surveys were compared for vitamin D national levels. Two NHANES studies were compared to determine if physical activity helped with vitamin D levels. Surveys and inperson interviews were conducted. The US has seen a significant decrease in vitamin D levels since the surveys conducted The mean level dropped 6ng/mL More activity resulted in higher vitamin D levels

13 VITAMIN D RECOMMENDATIONS 13 Alberts, et al. Aloia, et al. Tucson and Phoenix Cross-Sectional 619 Long Island Randomized, double-blind, placebocontrolled Participants in a colorectal adenoma prevention study 138 Healthy white and black adults age Blood samples were taken and questionnaires were answered about participants habits Different original levels of vitamin D determined the category and amount each subject was given to raise to an ideal level in six months 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. People with levels above 55 nmol/l need 3800 IU to reach an optimal state and those below 55 nmol/l need 5000 IU 4 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

14 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. Barker, 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 5 Blood samples were collected to determine vitamin D levels then surveys were completed to find sources of the vitamin Liu, et al. 4 Used previous data to determine if vitamin D levels are dependent on income, race/ethnicity, or gender Burnett- Bowie, et al. Caporaso, 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 5 Blood samples were taken from all participants to measure vitamin D Mean plasma 25(OH)D concentration Vitamin D level, diet, supplement usage, latitude of residence, ethnicity, age, and BMI Vitamin D concentrations and participant characteristics Vitamin D levels Vitamin D concentrations Plasma 25(OH)D concentrations improved for experimental group with increase of ng/ml for five days and only 1.37 ng/ml for placebo group. No significant changes for 90 or 365 days Depending on the current level of vitamin D, people are recommended either 3800 IU or 5000 IU to get their level back within reason. Higher vitamin D was associated with higher income, non- Hispanic white people. Women took more supplements. 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. 19.2% of Orange County residents were deficient (<30pg/ml) P<0.001 P<.05 Statistically significant depending on season P.05 P<0.1 No p-value recorded

15 VITAMIN D RECOMMENDATIONS 15 Connett, et al. Ameri, et al. Booth, et al. Camargo, et al. Camargo, et al. Alberts, et al. level. Demographics were also recorded. 5 Used data from three previous studies to find vitamin D status among participants 3 Participants either took vitamin D supplements or drank fortified orange juice to determine which was more effective 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. 5 Two National Health and Nutrition Examination Surveys were compared for vitamin D national levels. 4 Two NHANES studies were compared to determine if physical activity helped with vitamin D levels. Surveys and in-person interviews were conducted. 4 Blood samples were taken and questionnaires were answered about participants habits Vitamin D levels Vitamin D levels Vitamin D levels and fat indexes Vitamin D levels and recreational activities Comparison of two studies measuring 25(OH)D concentrations Serum 25(OH)D concentrations 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). Fortified orange juice is just as effective as supplementation at providing vitamin D. Lower vitamin D associated with: Higher BMI, Higher visceral and subcutaneous adipose tissues, Insulin resistance Mean level = 30 ng/ml ( ) Mean level = 24 ng/ml ( ). Levels <10ng/ml increased 2% to 6%. Levels 30 ng/ml decreased 45% to 23% 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<0.001 p=0.54 No significant difference P =.084 P >.1 P =.82 P < P = P < No p-value recorded p = P value < 0.05

16 VITAMIN D RECOMMENDATIONS 16 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 at 22.7% 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 to levels of 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). 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. Figure 2: Results of systematic analysis.

17 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 to (Camargo, et al, 2009). The ideal level is at least 30 ng/ml but with a drop of 6 ng/ml within 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

18 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

19 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

20 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.

21 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); Retrieved from 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): Retrieved from 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): Retrieved from 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): Retrieved from 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): Retrieved from

22 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): Retrieved from Boston University School of Public Health. (2013). The theory of planned behavior. Retrieved from 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): Retrieved from 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) Retrieved from e- 202e2259b44f%40sessionmgr4004&hid=4112&bdata=JnNpdGU9ZWhvc3QtbGl2ZQ%3 d%3d#an= &db=aph

23 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): Retrieved from Camargo, C. A. Jr., Ginde, A. A., Liu, M. C. (2009). Demographic differences and trends of vitamin D insufficiency in the US population, Archives of Internal Medicine. 169(6): Retrieved from 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): Retrieved from 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): Retrieved from Centers for Disease Control and Prevention. (2012). Second national report on biochemical indicators of diet and nutrition in the U.S. population Retrieved from 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): Retrieved from Davison, D. A., Hanley, D. A. (2005). Vitamin d insufficiency in North America. The Journal of Nutrition. 135(2): Retrieved from

24 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): Retrieved from 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): Retrieved from Forrest, K. Y. Z, Stuhldreher, W. L. (2011). Prevalence and correlates of vitamin d deficiency in US adults. Nutrition Research. 31(1): Retrieved from e- 202e2259b44f%40sessionmgr4004&hid=4112&bdata=JnNpdGU9ZWhvc3QtbGl2ZQ%3 d%3d#an= &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) Retrieved from 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 doubleblind clinical trial. PLoS ONE. 8(3). Retrieved from

25 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 Public Health Nutrition. 17(4): Retrieved from a.pdf&code=085cf59df4f c2e95bce65491e Mayo Clinic. (2014). Vitamin D: Evidence. Retrieved from 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): Retrieved from 06ed-40fc-96c2-e531c6181acf%40sessionmgr4002&vid=4&hid=4112 University of Twente. (n.d.). Theory of planned behavior/reasoned action. Retrieved from cation/theory_planned_behavior/ U.S. Department of Health and Human Services. (2014). Vitamin D: fact sheet for health professionals. Retrieved from HealthProfessional/ Vitamin D Council. (2014). Multiple sclerosis. Retrieved from Vitamin D Council. (n.d.). Am I deficient in vitamin D? Retrieved from

26 VITAMIN D RECOMMENDATIONS 26 Vitamin D Council. (n.d. a). Health conditions. Retrieved from Yetley, E. A. (2008). Assessing the vitamin D status of the US population. The American Journal of Clinical Nutrition. 88(20): Retrieved from