Despite the mounting scientiﬁc evidence that vitamin D sufﬁciency is required for optimal health, and that solar UVB irradiation is the main source of vitamin D for most Americans, the recommendations regarding vitamin D requirements and solar UVB exposure have not changed recently. There are signs, however, that the interest in vitamin D is increas-22,192 with subsequent increases in vitamin D requirements in the near future.193-195 The obstacles to doing so have been little proﬁt in selling solar UVB or vitamin D and concern that UV exposure carries with it the risk of skin cancer. However, it is noted that the amount of UVB irradiation required for optimal vitamin D levels is not very high and can be achieved with minimal risk of developing skin cancer or CMM. Frequent sunburns are an important risk factor for melanoma175 and BCC,170 and excess UV irradiation is an important risk factor for SCC;170 sunburn rates are high in the United States.196
Another impediment to increasing vitamin D dosage recommendations is that traditional epidemiological approaches have been slow to ﬁnd inverse correlations between vitamin D and cancer rates. However, a recent review revealed many of the studies considered only dietary vitamin D intake, which is generally inadequate and represents a small portion of total vitamin D intake and production. Studies that considered measures of total vitamin D intake and production generally found a signiﬁcant cancer risk reduction.105
Although the emphasis in this review is the effects of vitamin D in the United States, there is also a substantial vitamin D insufﬁciency in the United Kingdom (U.K.)197 and many other European countries. A recent review estimated that the economic burden due to vitamin D insufﬁciency in the United States is $40-53 billion per year; whereas, the economic burden due to excess UV irradiation is $5-7 billion. It is estimated that 50,000-70,000 U.S. citizens and 30,000-35,000 U.K. residents die prematurely from cancer annually due to insufﬁcient vitamin D.
Given the smaller U.K. population, the effect of vitamin D insufﬁciency is proportionally greater.
The problems regarding vitamin D status in Europe arise from several factors: (1) the countries are generally at higher latitudes; (2) the populations have become increasingly urbanized and spend more time indoors; (3) vitamin D fortiﬁcation is minimal in most European countries198 and recommended supplementation levels are too low (200 IU/day),199 resulting in widespread hypovitaminosis D;126,200 and (4) public health policy guidelines have not yet recognized the importance of vitamin D sufﬁciency for optimal health.197