People Who Should Avoid Vitamin D
If you have sarcoidosis, tuberculosis, or lymphoma it would be best for you to avoid vitamin D supplementation and UVB rays. It is recommended that you have Vitamin D blood tests, before you supplement with any sun exposure, tanning UVB units or oral vitamin D.
Drug Interactions
The following medications increase the metabolism of vitamin D and may decrease serum 25(OH)D levels: phenytoin (Dilantin), fosphenytoin (Cerebyx), phenobarbital (Luminal), carbamazepine (Tegretol), and rifampin (Rimactane). The following medications should not be taken at the same time as vitamin D because they can decrease the intestinal absorption of vitamin D: cholestyramine (Questran), colestipol (Colestid), orlistat (Xenical), mineral oil, and the fat substitute Olestra. The oral anti-fungal medication, ketoconazole, inhibits the 25(OH)D3-1-hydroxylase enzyme and has been found to reduce serum levels of 1,25(OH)D in healthy men. The induction of hypercalcemia by toxic levels of vitamin D may precipitate cardiac arrhythmia in patients on digitalis (Digoxin).
Understanding Vitamin D Cholecalciferol
The high rate of natural production of vitamin D3 cholecalciferol in the skin is the single most important fact every person should know about vitamin D because it has such profound implications for the natural human condition.
Vitamin D is a steroid hormone precursor that has recently been found to play a role in a wide variety of diseases. Current research indicates vitamin D deficiency plays a role in causing seventeen varieties of cancer as well as heart disease, stroke, hypertension, autoimmune diseases, diabetes, depression, chronic pain, osteoarthritis, osteoporosis, muscle weakness, muscle wasting, birth defects, and periodontal disease.
This does not mean that vitamin D deficiency is the only cause of these diseases, or that you will not get them if you take vitamin D. What it does mean is that vitamin D, and the many ways in which it affects a person's health, can no longer be overlooked by the health care industry nor by individuals striving to achieve and maintain a greater state of health.
Obtaining sufficient
vitamin D from natural food sources alone can be difficult. For many people,
consuming vitamin D-fortified foods and being exposed to sunlight are essential
for maintaining a healthy vitamin D status. In some groups, dietary supplements
might be required to meet the daily need for vitamin D.
Breastfed infants
Vitamin D requirements cannot be met by human milk alone, which provides only
about 25 IU/L. A recent review of reports of nutritional rickets found that a
majority of cases occurred among young, breastfed African Americans. The sun is
a potential source of vitamin D, but AAP advises keeping infants out of direct
sunlight and having them wear protective clothing and sunscreen. As noted
earlier, AAP recommends that exclusively and partially breastfed infants be
supplemented with 400 IU of vitamin D per day.
Older adults
Americans aged 50 and older are at increased risk of developing vitamin D
insufficiency. As people age, skin cannot synthesize vitamin D as efficiently
and the kidney is less able to convert vitamin D to its active hormone form. As
many as half of older adults in the United States with hip fractures could have
serum 25(OH)D levels <12 ng/mL (<30 nmol/L).
People with limited sun exposure
Homebound individuals, people living in northern latitudes (such as New England
and Alaska), women who wear long robes and head coverings for religious reasons,
and people with occupations that prevent sun exposure are unlikely to obtain
adequate vitamin D from sunlight.
People with dark skin
Greater amounts of the pigment melanin result in darker skin and reduce the
skin's ability to produce vitamin D from exposure to sunlight. Some studies
suggest that older adults, especially women, with darker skin are at high risk
of developing vitamin D insufficiency. However, one group with dark skin,
African Americans, generally has lower levels of 25(OH)D yet develops fewer
osteoporotic fractures than Caucasians.
People with fat mal-absorption
As a fat-soluble vitamin, vitamin D requires some dietary fat in the gut for
absorption. Individuals who have a reduced ability to absorb dietary fat might
require vitamin D supplements. Fat malabsorption is associated with a variety of
medical conditions including pancreatic enzyme deficiency, Crohn's disease,
cystic fibrosis, celiac disease, surgical removal of part of the stomach or
intestines, and some forms of liver disease.
People who are obese
Individuals with a body mass index (BMI) ≥30 typically have a low plasma
concentration of 25(OH)D; this level decreases as obesity and body fat increase.
Obesity does not affect skin's capacity to synthesize vitamin D, but greater
amounts of subcutaneous fat sequester more of the vitamin and alter its release
into the circulation. Even with orally administered vitamin D, BMI is inversely
correlated with peak serum concentrations, probably because some vitamin D is
sequestered in the larger pools of body fat.
