In fact, it has been proposed that annual fluctuations in vitamin D levels may explain the seasonality of influenza.(80) All of these factors point to the value of taking a daily vitamin D supplement to ensure optimal vitamin D intake.

Vitamin D has long provided significant support for healthy bone density.(81-86) However, scientists have also validated the critical role that vitamin D plays in regulating healthy cell division and differentiation, and its profound effects on human immunity.(87-90) These findings link a deficiency of vitamin D to a host of common age-related problems.

The current RDA is only 400 IU. As a result of startling evidence of a widespread vitamin D deficiency, prominent nutritional scientists are calling on Americans to increase their vitamin D intake to 1000 IU per day and higher. Currently, most experts in the field believe that intakes of between 1000 and 4000 IU for adults will lead to a more healthy level of serum 25(OH)D, at approximately 75 nmol/L.

Life Extension® recommends that healthy adults supplement each day with at least 1000 IU of vitamin D. Elderly adults may benefit from higher doses such as 2000 IU daily, and even up to 5000 IU daily.

Ingredients:
Each capsule contains:
Vitamin D3 1000 IU (250%DV)
Other Ingredients: rice flour, gelatin, sucrose, dl-alpha tocopherol, corn starch, magnesium stearate. Contains soybeans. Contains corn and rice.
Contains NO: milk, egg, fish, peanuts, crustacean shellfish (lobster, crab, or shrimp), tree nuts, wheat, yeast, or gluten. Contains NO artificial sweeteners, flavors, colors, or preservatives.

Recommended Use:
Adults: Take one capsule daily, or as recommended by a healthcare practitioner. This product is best utilized when taken in divided doses with fat-containing, low fiber meals.

Warning:
Individuals consuming more than 2,000 IU/day of vitamin D (from diet and supplements) should periodically obtain a serum 25-hydroxy vitamin D measurement. Toxicity is very unlikely in healthy individuals at a dose of less than 10,000 IU. Vitamin D supplementation is not recommended for individuals with hypercalcemia (high blood calcium levels). People with kidney disease, certain medical conditions (such as hyperparathyroidism or sarcoidosis), and those who use cardiac glycosides (digoxin) or thiazide diurectics should consult a physician before using supplemental vitamin D. Keep out of reach of children. Do not exceed recommended dose. Before using this product, consult your physician if you are undergoing treatment for a medical condition or if you are pregnant or lactating.

References:
79. Photochem Photobiol. 2007 Mar-Apr;83(2):459-63.
80. Epidemiol Infect. 2006 Dec;134(6):1129-40.
81. Rev Rhum Engl Ed. 1996 Feb;63(2):135-40.
82. Proc Nutr Soc. 2001 May;60(2):283-9.
83. J Bone Miner Res. 2003 Jul;18(7):1217-26.
84. Proc Natl Acad Sci USA. 2002 Oct 15;99(21):13487-91.
85. Steroids. 2001 Mar-May;66(3-5):375-80.
86. Bone. 2006 Oct;39(4):946-53.
87. Int J Cancer. 1984 Feb 15;33(2):193-202.
88. J Immunol. 1986 Apr 15;136(8):2734-40.
89. Cancer Res. 1985 Jan;45(1):311-6.
90. Endocrinology. 1984 Nov;115(5):1891-6.