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Nutrition & Supplements: Vitamin D Review

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The goal of every athlete, when it comes to competition, is to perform at the highest possible level. In order for this goal to be achieved the athlete must train their body to attain the necessary level of fitness that will allow them to excel within the parameters of their sport. Training alone will not necessarily result in the development of the athlete’s desired physique for their specific sport; proper nutrition is essential and must also be taken into consideration to provide the energy needed to maintain an intense training program. Many athletes and coaches alike are unaware of the detrimental effects that poor nutrition has on performance. This lack of knowledge in such a crucial area of performance has fueled the growth of the supplement industry in recent decades:

“Sports foods and supplements represent a multibillion dollar industry supported by aggressive marketing manufactures and word of mouth between athletes and coaches. Exercise scientists and sports nutrition practitioners are frustrated that the producers of supplements often make impressive claims without adequate, or sometimes any proof. However, in most countries the legislation regarding supplements is minimal or unenforced, allowing these unsupported claims to flourish.” (Burke, 2007, p. 16-17)

Due to the poor regulation of supplements throughout many countries of the world (including the United States) there are few answers to the multitude of questions asked by individuals looking to reap the benefits of supplementation. The key to avoiding negative repercussions when using a supplement of any kind is for athletes to conduct their own independent research on the supplement they plan to integrate into their training program. This process will bring to light the costs vs. benefits ratio along with the long term health effects. A crucial point that must be made clear is that supplementation is only necessary when an individual’s diet is lacking vital nutrients. This research paper will analyze the Vitamin D status in athletic and normal populations and will show whether Vitamin D supplementation is necessary and or beneficial.

Vitamin D- Functions, Metabolism, and Sources:

Vitamins and minerals role within the human body are to allow for crucial metabolic reactions that allow for the production of new tissues. Vitamins can be divided into two different categories: fat soluble and water soluble vitamins. The classification of vitamins into these two groups has to do with how the vitamin is utilized in the body: fat soluble vitamins are able to be stored in the body, while water soluble vitamins are easily excreted. These vitamins and minerals can be obtained from the environment in adequate levels. This poses the question: Is Vitamin D supplementation necessary for the general and athletic populations of the United States?: “Recent reports have suggested that more than half of the American adult and adolescent population use some form of supplement, with vitamin and mineral supplementation being the most widely reported.” (Hoffman, 2007, p. 26) Vitamin D is classified as a fat soluble vitamin and is stored in the subcutaneous fat beneath the skin; it is a crucial nutrient that is needed throughout one’s lifetime. A common misconception of this vital micronutrient is that it is a vitamin, while in actuality it is a pro-hormone. “Vitamin D was discovered with many other vitamins and is classified as a vitamin even now. However, findings from the second half of the 20th century showed that Vitamin D is truly a pro-hormone derived from cholesterol in the skin.” (DeLuca, 2004, p. 1689S) Vitamin D can be obtained from two natural sources: the predominant source is from skin exposure to ultraviolet radiation from the sun. Lesser quantities of Vitamin Dcan also be obtained from dietary intake of specific foods. These two sources allow the body to produce pre-vitamin D, which is then transformed by series of metabolic reactions into active Vitamin D. The process of Vitamin D metabolism is complex and is explained in detail by the research conducted by Hamilton and Chalabi (2010):

“Ultraviolet B radiation acts on the skin to convert 7-dehydrocholesterol to pre- vitamin D3. In the dermis of the skin, pre-vitamin D3 is rapidly converted to vitamin D3 (cholecalciferol), before being converted to 25-hydroxycholecalciferol-vitamin D in the liver. A final hydroxylation of 25-hydroxycholecalciferol-vitamin D into the active form of Vitamin D (calcitriol) occurs in the kidneys.” (p. 11-12)

The greatest and most beneficial source of Vitamin D is obtained from exposure of skin to sunlight. However, Vitamin D3 and Vitamin D2 (ergocalciferol) canbe obtained though dietary sources. “Mammalian cholesterol is used to produce Vitamin D3 while Vitamin D2 is derived from the plant sterol ergosterol.Ergocalciferol appears to be only about 20-40% as effective as Vitamin D3 at increasing and maintaining an adequate level of25-hydroxycholecalciferol-vitamin D.” (Willis, Peterson, and Larson-Meyer, 2008, p. 206) Dietary sources of Vitamin D are fatty fish (cod liver oil, salmon, mackerel, and tuna) mushrooms, fortified cereals, egg yolks, and yeast products, however dietary sources of Vitamin D alone are not capable of supplying the body with the necessary amounts of Vitamin D for optimal health.

http://junction25.com/wp-content/plugins/three-column-screen-layout/db.php The Role of Vitamin D in the Human Body:

Vitamin D is essential to the health of the human body. The discovery of Vitamin D and the elimination of Rickets as a significant medical problem was a momentous step forward in medicine. (DeLuca, 2004, p. 1689S) However, this micronutrient has in recent years been proven to have a much greater influence in the human body than previously acknowledged, “It is well recognized that an adequate Vitamin D status is necessary for optimal bone health, but emerging evidence is finding that Vitamin D also plays a role in preventing autoimmune diseases and non-skeletal chronic diseases; it can also have a profound effect on human immunity, inflammation, and muscle function.” (Willis, Peterson, and Larson-Meyer, 2008, p. 204) The discovery of the extensive role that Vitamin D plays in the body has made it a priority in many research studies. These research studies aim to analyze whether or not the RDA of Vitamin D are satisfactory in promoting an adequate Vitamin D status, what risk factors may put Americans at risk for developing Vitamin D deficiency, and whether Vitamin D supplementation is an effective way to maintain a healthy Vitamin D blood serum level.

Buy Diazepam 5Mg Tablets Uk The Effects of Vitamin D Deficiency Upon Overall Health:

Deficiency of Vitamin D in the human body has been proven to have devastating effects on overall health. Vitamin D deficiency is often unrecognized in the everyday population. Symptoms are usually non-specific and consist of:fatigue, depression, insomnia back pain, proximal muscle weakness, headache, and hair loss. Recent research connects this micronutrient with many aspects of homeostasis. Deficient levels that are endured over an extended period of time have been proven to increase the risk of numerous chronic diseases that pose the risk of severe impairment and even early mortality.

“Poor Vitamin D intake and low blood levels of Vitamin D metabolites are associated with increased incidence and severity of several autoimmune diseases . . . including multiple sclerosis, rheumatoid arthritis, Type I diabetes, systemic lupus erythematosis, and psoriasis . . . Lower levels of Vitamin D increase the risk of hypertension, myocardial infarction and death due to cardiovascular disease.”(Qamar and Fabian, 2010, p. 99).

Newly formulated research has shown that an overwhelming proportion of the American public is Vitamin D deficient. In order to measure what the optimum and deficient levels of Vitamin D in the body are health professionals must first be able to accurately assess ones Vitamin D status. Evaluating an individual’s Vitamin D status is achieved by measuring the blood serum levels of 25-hydroxyvitamin D:Vitamin D deficiency classification (<25-27.5 nmol/L), Vitamin D insufficiency classification (<25-37.5nmol/L), Adequate Vitamin D status (> 37.5 nmol/L), and Toxic levels of Vitamin D (Consistently greater than 500 nmol/L). (Morris, 2010, p. 15)Vitamin D deficiency has been seen to exist in every age group and is present despite vitamin supplementation and consumption of foods fortified with Vitamin D. There are specific populations that health professionals have associated with an increased risk for developing a Vitamin D deficiency: those who do not take supplements, are advanced in age, have darkly pigmented skin, are obese, avoid sun exposure, and live in a highly polluted environment.

“The National Health and Nutritional Examination Survey (NHANES III) produced data showing that despite Americans consuming more than the recommended of Vitamin D (average consumption was greater than 280 IU/day) that blood serum concentration levels were deficient.” (Willis, Peterson, and Larson-Meyer, 2008, p. 206) These findings have caused the need for current RDA values of Vitamin D intake to be re-evaluated.

Vitamin D Supplementation:

Due to the overwhelming proportion of the American population that has been classified as Vitamin D deficient supplementation is now being highly recommended. Data produced by Garland et al, suggests that “increasing the blood serum levels of 25-hydroxyvitamin D to levels of 40 to 60 ng/ml would provide multiple health benefits for U.S. citizens.” This blood serum level would require a total in take of 4000 IU daily from all sources.In order for the average American citizen to achieve this value supplementation would be necessary. The benefits that occur from Vitamin D supplementation are directly correlated to the degree that the individual is deficient. The lower the 25-hydroxyvitamin D serum concentration the more aggressive the vitamin D supplementation must be. Many supplements provide only 400 IU of Vitamin D which is not adequate with reversing a deficient Vitamin D status.

“Daily requirements for Vitamin D are around 800 to 1000 IU, but larger doses are needed for patients who are already suffer from Vitamin D deficiency, that is 15-25 nmol/L, oral supplementation with 300-5000 IU daily for 6-12 weeks will replete stores with a dose of 100-2000 IU per day . . . For severe deficiency, that is 25-hydroxyvitamin D less than 13 nmol/L the intramuscular form of cholecalciferol 100,000 IU (megadose therapy) may be needed to replenish stores quickly and effectively.” (Joshi, Center, and Eisman, 2010, p 105)

Oral supplementation of Vitamin D is the most common in practice due to its availability and relative low cost (approximately 11-16 cents per capsule).In order to optimize the absorption of these supplements they should be taken with a meal containing fat. (Kennel, Drake, and Hurley, 2010, p. 755)

Vitamin D supplementation has been shown to provide benefits for those of normal Vitamin D status as well as those with a diagnosed deficiency. Vitamin D supplements can be bought over the counter at a local pharmacy or specifically prescribed by a physician. A note of caution for those supplementing without a prescription is that Vitamin D toxicity can be caused by excess oral intake, but not by prolonged exposure to sunshine. Obtaining an individually prescribed supplementation plan is most effective method curing a Vitamin D deficiency. Oral supplementation in the form of Cholecalciferol (Vitamin D3) is given at a dose of 1000 IU or 25 micrograms is the dosage most commonly prescribed. (Joshi, Center, and Eisman, 2010, p 105) The type of Vitamin D prescribed must be taken into consideration by the prescribing physician in order for supplemental treatment to be monitored effectively. Vitamin D supplements that contain only Vitamin D2 may not be detected using standard blood serum testing due to the fact that it is less physiologically active than its counterpart Vitamin D3. (Mula-Abed, 2009, p.240) An individual who is diagnosed with a Vitamin D deficiency must be sure to carefully follow the prescribed dosage plan carefully in order to allow medical professionals to provide accurate feedback of one’s current Vitamin D status.

Buy Original Phentermine Online The Influence of Vitamin D Status on Athletic Performance:

An athlete’s performance depends on two vital components: a sports specific training regimen for the development of strength, conditioning, and skill as well as a balanced nutritional plan to allow for recovery between training sessions. Vitamin D deficiency is currently considered to be an epidemic in all age groups in the United States. The assumption that must be made is that athletic populations are also at risk for developing a deficiency in this crucial micronutrient. Unfortunately, Vitamin D has been largely ignored as a nutrient in sports nutrition. Due to the lack of research, an ability to accurately assess the Vitamin D status in athletic populations is not available. As previously discussed a low blood serum level of Vitamin D metabolites can have significant effects on the overall health of an individual.“Of the studies that have assessed Vitamin D intake, it has been found that athletes in general report consuming far less than the current daily recommendation for Vitamin D despite presumably having higher energy needs than the general population.” (Willis, Peterson, and Larson-Meyer, 2008, p. 209) The discovery of the increased role of Vitamin D in the human body brings about the conclusion that Vitamin D supplementation may have substantial benefits in improving athletic performance. Research suggests that Vitamin D may help to maintain health during periods of intense training such as preventing stress fractures in bones, increased immunity, and maintaining muscle strength/preventing muscle loss.

“The actions of Vitamin D depend on Vitamin D receptors . . . and the presence of the [Vitamin D] receptors in human muscle cells were confirmed in 2001. As is typical with all steroid hormones, the binding of Vitamin D to its receptor results in enhanced transcription of proteins, particularly those involved in calcium metabolism. . . It is very likely therefore, that Vitamin D may affect muscle function through both calcium related protein transcription and total body calcium levels.” (Hamilton and Chalabi, 2010, p. 13)

It is a well known fact that the energy requirements for athletes are significantly higher than that of the general population due to their increased energy expenditure associated with training and competition. “Despite increased training; there is no evidence to suggest that the Vitamin D requirement in athletes is different than for the general population. (Willis, Peterson, and Larson-Meyer, 2008, p. 215) However, this research does not suggest that Vitamin D supplementation among athletes is not recommended. Certain factors such as: indoor competition/training, time of season, body fat levels, and dietary practices are unique to all sports and may cause a deficiency in athletes. More research is needed but current recommendations for athletes concerning Vitamin D supplementation are between 800 and 2,000 IU/day (Willis, Peterson, and Larson-Meyer, 2008, p. 216). The exact dosage depends on the individual athlete’s current Vitamin D blood serum levels along with the risk factors of their specific sport (listed above). Athletes who feel they are at risk for developing a deficiency should contact their physician or another medical professional so that they can be assessed accurately.


Vitamin D is an essential micronutrient that is needed throughout one’s life time. Vitamin D is fat soluble and is a pro-hormone derived from cholesterol stored in the subcutaneous fat underneath the skin. Recent research has proven that Vitamin D plays an important role in bone health, calcium absorption, chronic-disease prevention, immunity, and the homeostasis of multiple organs in the body. In order for the body to use Vitamin D it must first be metabolized. There are two sources of Vitamin D available; the first and most abundant source is from ultraviolet radiation. Approximately five to thirty minutes of sun exposure twice a week (depending on one’s geographic location and time of day) on twenty-five percent of one’s body is proven to provide an adequate source Vitamin D. Vitamin D is also available from specific foods, however these sources are limited and will not provide enough Vitamin D alone to meet RDA values. Vitamin D deficiency is now considered an epidemic among all age groups in the United States despite most Americans consuming greater than the recommended quantities. This suggests that the recommended values for Vitamin D consumption need to be re-evaluated. This alarming statistic has also led to health and medical professionals strongly recommending Vitamin D supplementation for those who are deficient and for those looking to prevent deficiency. Despite the differences in energy intake there is no evidence to suggest that Vitamin D needs are different for athletes compared to the general population. More research is necessary in order to accurately determine current Vitamin D status among athletic populations and whether or not Vitamin D supplementation can provide an increase in athletic performance.

Reference List

Burke, L. (2007). Practical Sports Nutrition. Champaign, IL: Human Kinetics

DeLuca H.F. (2004). Overview of general physiologic features and functions of Vitamin D. American Society for Clinical Nutrition, 80:1689S-96S

Garland C.F., Gorham E.D., Mohr S.B. (2009) Vitamin D for cancer prevention: Global perpective. Ann Epidemiol 19: 468-483

Hamilton B. and Chalabi H. (2010) Vitamin D: An Update For The Medical Sports Medicine Practicioner. SportEX Medicine, 43:11-16

Hoffman J.R. (2007) Protein Intake: Effect of Timing. Strength and Conditioning Journal. Volume 29, Issue 6:26-34

Joshi D., Center J.R. and Eisman J.A. (2010) Vitamin D deficiency in adults. Austrailian Prescriber., Volume 33, Issue 4: 103-106

Kennel K.A., Drake M.T., Hurley D.L. (2010). Vitamin D Deficiency in Adults: When to Test and How to Treat. Mayo Foundation for Medical Education and Research, 85(8): 752-758

Kentz W.S., Peterson N.J. and Larson-Meyer E.D. (2008). Should We Be Concerned About the Vitamin D Status of Athletes? International Journal of Sport Nutrition and Exercise Metabolism, 18:204-224

Morris M.M. (2010). Vitamin D- An Essential Requirement For a Lifetime. Nutritional Perspectives: Journal of the Council on Nutrition of the American Chiropractic Association, Volume 33, Issue 3:14-20

Mula-Abed W.A. (2009). 25- Hydroxyvitamin D: Explosion Interest and Laboratory Requests. Oman Medical Journal, Volume 24, Issue 4:239-241

Qamar K.J., Fabian C.J. (2010). How I Treat Vitamin D Deficiency. American Society of Clinical Oncology, Volume 6, Issue 2: 97-10

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