Just be careful of toxicity and interactions with other medications..
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Health Risks from Excessive Vitamin D
Vitamin D toxicity can cause nonspecific symptoms such as nausea, vomiting, poor appetite, constipation, weakness, and weight loss [87]. More seriously, it can also raise blood levels of calcium, causing mental status changes such as confusion and heart rhythm abnormalities [7]. The use of supplements of both calcium (1,000 mg/day) and vitamin D (400 IU/day) by postmenopausal women was associated with a 17% increase in the risk of kidney stones over 7 years in the Women's Health Initiative [88]. Deposition of calcium and phosphate in the kidneys and other soft tissues can also be caused by excessive vitamin D levels [46]. A serum 25(OH)D concentration consistently >200 ng/mL (>500 nmol/L) is considered to be potentially toxic [11]. In an animal model, concentrations ≤400 ng/mL (≤1,000 nmol/L) were not associated with harm [14].
Excessive sun exposure does not result in vitamin D toxicity because the sustained heat on the skin is thought to photodegrade previtamin D3 and vitamin D3 as it is formed [10,35]. High intakes of dietary vitamin D are very unlikely to result in toxicity unless large amounts of cod liver oil are consumed; toxicity is more likely to occur from high intakes of supplements.
Long-term intakes above the UL increase the risk of adverse health effects [4] (Table 4). Substantially larger doses administered for a short time or periodically (e.g., 50,000 IU/week for 8 weeks) do not cause toxicity. Rather, the excess is stored and used as needed to maintain normal serum 25(OH)D concentrations when vitamin D intakes or sun exposure are limited [11,89].
Table 4: Tolerable Upper Intake Levels (ULs) for Vitamin D [4]Age Children Men Women Pregnancy Lactation
Birth to 12 months 25 mcg
(1,000 IU)
1-13 years 50 mcg
(2,000 IU)
14+ years 50 mcg
(2,000 IU) 50 mcg
(2,000 IU) 50 mcg
(2,000 IU) 50 mcg
(2,000 IU)
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Interactions with Medications
Vitamin D supplements have the potential to interact with several types of medications. A few examples are provided below. Individuals taking these medications on a regular basis should discuss vitamin D intakes with their healthcare providers.
Steroids
Corticosteroid medications such as prednisone, often prescribed to reduce inflammation, can reduce calcium absorption [90,91,92] and impair vitamin D metabolism. These effects can further contribute to the loss of bone and the development of osteoporosis associated with their long-term use [91,92].
Other medications
Both the weight-loss drug orlistat (brand names Xenical® and alli) and the cholesterol-lowering drug cholestyramine (brand names Questran®, LoCholest®, and Prevalite®) can reduce the absorption of vitamin D and other fat-soluble vitamins [93,94]. Both phenobarbital and phenytoin (brand name Dilantin®), used to prevent and control epileptic seizures, increase the hepatic metabolism of vitamin D to inactive compounds and reduce calcium absorption [95].
I am very fair and there is NO POSSIBLE WAY for me to absorb the amount of VIT D that I need from the sun alone. And you can only drink so much milk(you'd need 10 glasses a day.) So my doc just started me on 1000u per day. I also just found out I'm pre-diabetic, and the doc says VIt D helps control blood sugar.
