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Source Naturals Vitamin D-3Source Naturals Vitamin D-3
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Source Naturals Vitamin D-3

Bioactive Form For Bone and Immune Health from Source Naturals
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Retail $10.25
 (Save 42%)
Size: 200 Tablets - 1,000 IU
Item: 5410
Weight: 0.25 lbs
Vitamin D-3 maintains healthy calcium and phosphorus levels in the body for strong bones; it increases muscle strength in older adults; and it also plays an active role in a healthy immune response. It also plays an important role in regulating cell growth, insulin levels, and bone formation.

  • Description
  • Supplement Facts
  • Contraindications
  • Reviews

Sunlight is the source of life on Earth, but we may not be aware of all the ways it benefits us. Our bodies manufacture vitamin D-3 when the skin is exposed to UV radiation from sunlight, but the ability to do so decreases as we age.

Vitamin D-3 maintains healthy calcium and phosphorus levels in the body for strong bones; it increases muscle strength in older adults; and it also plays an active role in a healthy immune response. Vitamin D-3 (cholecalciferol) is the optimal form of vitamin D. It is the form of vitamin D that the body manufactures in sunlight, and the form most efficient for the body’s needs.

Why We Need Vitamin D

New research indicates that our modern indoor lifestyles may lead to a widespread increase in vitamin D deficiency.  Nicknamed the “sunshine vitamin” because the body makes it naturally when exposed to the sun, scientists are discovering that vitamin D-3 is an important hormone precursor that helps support the immune system and helps regulate the health of at least 20 different tissues, including the brain and joints.

Vitamin D-3 also plays an important role in regulating cell growth, insulin levels, and bone formation. Researchers are finding that the current recommended daily allowances of vitamin D — ranging from 200 international units for infants, children and adults up to age 50 years; 400 IU for men and women from 50 to 70; and 600 IU for people older than 70 — may be far lower than what is necessary for optimum health.

Vitamin D-3 addresses seven of the twelve metabolic systems of the body, systems crucial to vibrant health. For example:

  • Cells/DNA
  • Inflammation Response
  • Metabolism
  • Hormones
  • Cognition/Nerves
  • Immunity 
  • Structure/Connective
Read More on our Blog
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Deficiency Is Widespread

Vitamin D insufficiency may be quite common in places far from the equator and researchers estimate that 50% of Americans may have less vitamin D than they need. Today’s teens also have less exposure to direct sunlight and have switched from drinking vitamin D fortified milk to soda. Puberty is a very critical time when up to half of a person’s adult bone mass is being deposited, and vitamin D helps ensure that people have normal blood levels of calcium for this important process. New research estimates that 30 percent of adolescents nationwide may be vitamin D deficient.

Deficiency Risk for African Americans
People of African descent require up to 30 minutes sun exposure three times weekly during summer on the face, arms, and hands, while very fair-skinned Caucasian people require 5-10 minutes. African-Americans have the highest risk for vitamin D deficiency because dark skin needs 5 to 10 times more sunlight than Caucasian skin to produce the same amount of the vitamin. One study found that 42 percent of African-American women in the U.S. were vitamin D deficient.

While the use of sunscreen is imperative for skin health, sunscreen that is sun protection factor 8 (SPF 8) or greater blocks 95% of the UVB light needed for the skin to synthesize vitamin D.

Deficiency Risk for Older Adults
Older adults may also be at particularly high risk: After age 50 the requirement for vitamin D doubles because the body is less able to make its own vitamin D. In a report in the Journal of the American Geriatrics Society in February 2004, researchers at the University of Basel in Switzerland showed that elderly women who took a vitamin D supplement plus calcium for three months reduced their risk of falling by 49% compared with consuming calcium alone. Those women who had fallen repeatedly in the past seemed to gain the most benefit from vitamin D.

Uterine Fibroid Tumors and Vitamin D3

An exciting study from the National Institutes of Health (NIH) reports that Vitamin D may be a key player in helping to manage fibroid tumors. NIH says, "In previous research, the study authors found that vitamin D inhibited the growth of human fibroid cells in laboratory cultures." This is exciting for women because as the researchers point out, this could provide "a promising new lead in the search for non-surgical treatment of fibroids that doesn't [negatively] affect fertility." Read more in our blog Reserach Points to Vitamin D to Help Shrink Fibroid Tumors.

Vitamin D: Aches and Pains

Fibromyalgia, as well as generalized aches and pains not meeting the diagnostic criteria for fibromyalgia have been attributed by some researchers to vitamin D deficiency. For example, a large German study examined 994 people and found a strong correlation between low vitamin D levels and higher rates and longer duration of generalized bone and/or muscle aches and pains.

A study published in the Mayo Clinic Proceedings examined 150 people with persistent, non-specific musculoskeletal pain in Minnesota. The researchers found that 93% of them had deficient levels of vitamin D.

Furthermore, in another study, vitamin D levels were assessed in 75 people who fulfilled the American College of Rheumatology criteria for fibromyalgia. Although there was no relationship between vitamin D levels and musculoskeletal symptoms, vitamin D deficiency was linked to anxiety and depression in people with fibromyalgia.

Healthy Cell Proliferation

Vitamin D research is an emerging area of interest for scientists, who have yet to understand the many roles of this important vitamin in the body. While vitamin D’s main function is to maintain normal levels of calcium and phosphorus in the blood, vitamin D also serves as a hormone precursor. Once it has been converted into its active form, it can enter a cell, cross the nuclear membrane, attach to specific receptors on the DNA or its protein wrapping, and promote cell differentiation. Vitamin D is one of the body’s many control systems, acting like an emergency brake to stop cells from perilously misbehaving.

Important Immune Booster Against Colds and Flu

Vitamin D is a nutrient that helps regulate hundreds of genes, including those involving the body’s innate immunity and its defenses against viruses, especially those affecting the respiratory system. 

Until the 1980’s no one understood the role that Vitamin D played in the functioning of the immune system.  However, current studies are beginning to show the link between low vitamin D levels during the winter months and one’s decreased immunity and susceptibility to colds and flu.

According to Michael Holick, a vitamin D researcher at Boston University School of Medicine, “immune cells have a vitamin D receptor, and that the cells activate vitamin D as a response to infection…First it is used by immune cells to fight a virus.  Then, it helps temper the overall immune response and limit inflammation.”

A report of the largest study regarding the association between vitamin D and respiratory infections appeared in the Archives of Internal Medicine.  This study found that people with the lowest blood levels of this nutrient reported a significant increase in recent cases of colds and flu.

Vitamin D and Bone Health

It is estimated that over 25 million adults in the United States have, or are at risk of developing, weakened bones as they age. Having normal storage levels of vitamin D in the body helps keep bones strong, especially in elderly, non-ambulatory individuals, and post-menopausal women.

Vitamin D and Blood Pressure

Vitamin D may also support healthy blood pressure. Scientists noticed that blood pressure levels vary with the season—they tend to be highest during autumn and lower during the warmer months of spring and summer.

Researchers studied people’s blood pressure and the levels of vitamin D in their blood and discovered a connection between higher vitamin D levels and decreased blood pressure. The body controls blood pressure through the renin-angiotensin system, with high renin levels leading to increased blood pressure. Cutting edge research has shown that vitamin D regulates renin levels through genetics, which may be the critical way in which this vitamin supports cardiovascular health.

Fibromyalgia and Vitamin D3

A deficiency of this nutrient is common in people with fibromyalgia.  Studies have shown that Vitamin D can help reduce fibro-fog, pain and muscle weakness, improve immune function, and support healthy bone formation.  In addition, some health care professionals feel Vitamin D-3 can help with Seasonal Affective Disorder also.

Fibromyalgia sufferers frequently complain of cognitive problems or "fibrofog." The existence of these symptoms has been confirmed by studies of the incidence of cognitive problems in fibromyalgia patients and by the results of objective tests of metamemory, working memory, semantic memory, everyday attention, task switching, and selective attention.

The results of these tests show that fibromyalgia patients have impairments in working, episodic, and semantic memory that mimic about 20 years of aging. These patients have particular difficulty with memory when tasks are complex and their attention is divided. Cognitive symptoms in these patients may be exacerbated by the presence of depression, anxiety, sleep problems, endocrine disturbances, and pain, but the relationship of these factors to cognitive problems in fibromyalgia patients is unclear.

According to a study published in the Journal of Neurology, Neurosurgery, and Psychiatry:

Thinking or cognitive impairments in elderly men are shown in new research to be associated with low Vitamin D levels. A study of three thousand European men, 40-79 yrs. old, demonstrated that people with reduced amounts of Vitamin D in their body did not score as well on a cognitive ability standardized test (assessment of individual’s attention and speed of information processing) as others did with standard levels of Vitamin D.

Their average level of Vitamin D among the elderly men was 63 nanomoles per liter. However, 90-140 nanomoles per liter is usually deemed as optimal. Men over age 60 with Vitamin D levels below 35 nanomoles per liter strongly illustrated less cognitive presentation. Research is still being conducted to see if Vitamin D supplementation can definitely improve cognition.

SOURCE: Journal of Neurology, Neurosurgery, and Psychiatry, May 21, 2009 online issue

Further Reading

Am I Vitamin D Deficient?

Nutritional Aspects of Vitamin D

Vitamin D Research

Phys Ed: Can Vitamin D Improve Your Athletic Performance?

Vitamin D Pills May Prevent Fractures in Older Adults

Aging: Vitamin D Levels Tied to Dementia Risk

American Children Vitamin D Deficient


Argiles, A. 2002. Blood pressure is correlated with vitamin D3 serum levels in dialysis
patients. Blood Purif: 20(4):370-5.

Borissova, A-M. The effect of vitamin D3 on insulin secretion and peripheral insulin
sensitivity in type 2 diabetic patients. IJCP 2003:57(4): 258-261.

Hung, M. Higher Vitamin D Intake Associated With Lower Risk of Rheumatoid Arthritis. Medscape Medical News Jan. 9, 2004 Li YC. 2003.

Vitamin D regulation of the rennin-angiotensin system. J Cell Biochem 2003:88(2):327-31.

Wiley Interscience. Merlino, L. Vitamin D intake is inversely associated with rheumatoid arthritis: results from the Iowa women’s health study. Arthritis and Rheumatism 2004(1):72-77.

American College of Rheumatology, 2004. Monger, KL. Vitamin D intake and incidence
of multiple sclerosis. Neurology 2004:62(1):60-65.

AAN Enterprises, Inc. Rucker, D. Vitamin D insufficiency in a population of healthy western Canadians. CMAJ 2002: 166(12): 1517-1524.

Supplement Facts

Capsules per Container: 200 Tablets - 1,000 IU
Serving Size:  Two (2) Tablets
Servings per Container:  100
Suggested Use:  One to two tablets daily with a meal, or as directed by your health care professional. 

Supplement Facts for 1,000 IU Tablet
Serving Size: Two tablets
Amount per Serving % Daily Value
Vitamin D-3 (as cholecalciferol) 2000 IU 500%

Other Ingredients: microcrystalline cellulose and stearic acid.

Contains no yeast, dairy, egg, gluten, soy, wheat, sugar, starch, salt, preservatives, or artificial color, flavor, or fragrance.

Warning: If you are pregnant, may become pregnant, breastfeeding, have kidney, parathyroid, or any lung disease, cancer, and/or are taking any prescription medication, consult your physician before taking this product. Do not exceed a total of 2,000 IU of vitamin D per day from all sources, including multivitamins and fortified milk. Do not use if either tamper-evident seal is broken or missing. Keep out of the reach of children.

Manufactured by Source Naturals

Contraindications, Interactions, and Side-Effects for Vitamin D

Before taking any high-potency vitamin D product, if you have any heart or kidney disease, or if you are taking Digitalis, Orlistat (Xenical), Cholestyramine (Questran), or antacids with aluminum, please check with your health care provider before taking this product.

While vitamin D toxicity is much more rare than vitamin D deficiency, you should be aware of symptoms that may happen if you are taking too much vitamin D. These would include breathing problems, tightness in throat or chest, skin hives, rash, or itchy or swollen skin. If you experience any of these symptoms stop taking this product for several days. If symptoms do not stop, then it probably isn't the vitamin D that is causing these symptoms and other possible causes need to be investigated. If symptoms stop, reintroduce the product by taking half of what you were previously taking. If you are not sure if these symptoms are related to your vitamin D intake, please consult with a health care professional, especially when it come to tightness in the chest.


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† These statements have not been evaluated by the U.S. Food and Drug Administration (FDA) or This product is not intended to diagnose, treat, cure or prevent any disease. The information provided on this site is for informational purposes only and is not intended as a substitute for advice from your physician or other health care professional or any information contained on or in any product label or packaging. You should not use the information on this site for diagnosis or treatment of any health problem or for prescription of any medication or other treatment. You should consult with a health care professional before starting any diet, exercise or supplementation program, before taking any medication, or if you have or suspect you might have a health problem, or are pregnant.

When you receive an item, carefully read all labels, warnings, and directions before use. Actual product packaging and materials may contain more and/or different information than shown on this website.

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