"Rationale: The UL for infants was set on the basis of a NOAEL of 45 µg/day (Fomon et al 1966, Jeans & Stearns 1938) together with a UF of 1.8 (FNB:IOM 1997) because of the small sample sizes and insensitivity of the endpoint used (linear growth). For children and adolescents, there are little available data, so the recommendation for adults was adopted.
The UL for adults was based on studies assessing the effect of vitamin D on serum calcium in humans (Honkanen et al 1990, Johnson et al 1980, Narang et al 1984, Vieth et al 2001). Johnson et al (1980) and Honkanen et al (1990) conducted studies with supplementation at 50 µg/day or 45 µg/day for several months and saw no adverse effects. Narang et al (1984), using dosages of 60 µg and 95 µg/day over several months in a non-randomised trial that included 30 normal controls, saw increases above 2.75 mmol/L in serum calcium levels a level considered as defining hypercalcaemia, at 95 µg/day but not at 60 µg/day. However, a recent, well-designed, RCT by Vieth et al (2001) saw no adverse effect of dosages of 25 µg/day or 100 µg/day over six months in 30 subjects. This finding was confirmed in a later randomised study (Vieth et al 2004) of inpatients with subclinical or marginal deficiency. Vieth et al (2001) felt that the earlier data of Narang et al (1984) may have been erroneous in dosage, citing concerns about lack of independent confirmation of the actual amount of vitamin D administered (there were no measures of serum 25(OH)D). There is also some animal evidence of oral vitamin D causing non-calcified atherosclerosis of large arteries (Taura et al 1979, Toda et al 1985), suggesting that a cautious approach should be taken to high dose vitamin D in people other than the elderly.
Taking all of this into account, the figure of 100 µg/day from Vieth's studies was adopted as the NOAEL and a UF of 1.2 was applied because of the inconsistencies in the studies and they were performed on relatively small number of subjects with pre-existing marginal vitamin D status. Vieth et al (2001) have themselves cautioned about the relatively small numbers in their studies."
I have personally been researching a number of avenues in regards to the health of my wife and myself over the last 5 years. Coming out of winter in 2015 I decided to measure my 25(OH)D levels and found them at 61 nmol/L in the range 50-150. My research indicated that this was less than what I wanted but nevertheless established a baseline for my own experimentation. I began supplementing at 5000IU daily with the product I obtained through iHerb and which most recently you have seized at the border. There are many potential benefits of having high serum levels of 25(OH)D and it appears that the NZ Ministry of Health only focuses on the potential for decreasing risk of osteoporosis.
However, Vitamin D functions within two systems in the human body:
- The endocrine system - maintains calcium homeostasis and bone health. This system uses the metabolized form of vitamin D called 25(OH)D and by the time it is turned into 1,25(OH)2D, the usable form, it has a half life of three weeks. All the studies on bone health have been successful based on dosage, not frequency, because of this long half life.
- The autocrine/paracrine system - vitamin D is delivered to non-skeletal systems such as breast, colon, and prostate tissues and helps affect autoimmune disorders, cancer, cardiovascular disease and infections. In this system, vitamin D goes into a cell and helps regulate cell growth, after this process vitamin D has a half life of 24 hours, meaning frequency of dosing matters when testing for disease reduction and immune control.
Two of the possible effects of vitamin D are in reducing uric acid and inflammation. As ldl cholesterol is a marker for inflammation my experience is that supplementation with vitamin D has shown up markedly in my lipid and uric acid levels in the following graph. I had been gradually increasing my uric acid, triglyceride and ldl-c levels (consistent with insulin resistance) up until I adopted a lifestyle intervention around the beginning of 2014. My supplementation of vitamin D began around October/November 2015.
I am 63 and on no medications apart from the D3 and K2 which I supplement. I believe that I was approaching a state of pre-diabetes until I took charge of my own health and intervened in lifestyle choices. One of those choices was to supplement at a rate of 5000IU of D3, which is not excessive by overseas practice. While I understand it is possible for me to get a prescription from my doctor to qualify for 'reasonable excuse' under your guidelines, I foresee a potential conflict in that my doctor is guided by you and will potentially be going against your concept of 'best practice' unless he follows your published criteria. As it was, he refused to schedule a lab test for 25(OH)D when I wanted one back in 2015, which refusal caused me to have to pay $40 for my own assay.
From my position it seems that guidelines from authorities like Ministry of Health on the likes of 'healthy eating' and 'healthy sun exposure' as well as setting lower criteria for prescribing statin medications, are resulting in increasingly poor health outcomes for New Zealanders. I have reversed some poor trends in my own health by ignoring such guidelines and following my own research. To be forced to abide by MOH regulations for my vitamin D supplementation is putting my health at unnecessary risk and I hope you will take the content of my letter as being 'reasonable excuse' for allowing my D3 supplement through the border.