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Nigel Kinbrum
Vitamin D is known as the "Sunshine Vitamin" and it was once thought that a deficiency in it was rare and that it was only involved in calcium homeostasis in bones, and that a lack of it only caused Rickets/Osteomalacia. Recent research however has shown that not only is Vitamin D involved in a whole host of bodily processes but that a deficiency in it is actually very common, leading to a whole host of degenerative diseases.
A good overview on Vitamin D can be found here. An informative 1 hour presentation called "Vitamin D deficiency: The Cause of Everything?" can be found here.
According to Hyppönen & Power, in a large sample of the white British population born in 1958, 60.9% of subjects had serum 25(OH)D (the active metabolite of Vitamin D) of <75nmol/L in Summer & Autumn, and 87.1% had serum 25(OH)D of <75nmol/L in Winter & Spring.
Here's my experience of Vitamin D3. For many years, I was struggling to cope with my job and I eventually took early retirement on the grounds of ill-health. In mid-2006 I was given a serum 25(OH)D test and the result was 73nmol/L. As the Reference Range for serum 25(OH)D is 33.1-129 nmol/L, I was technically not deficient in Vitamin D. Subsequent events suggested otherwise.
In January 2007, after reading the above study and a study by Vieth, Kimball, Hu & Walfish, I began to supplement with 2,000iu/day of Vitamin D3 and also used a UVB+IR lamp for 3 minutes each night. At first, nothing happened and I was pretty sceptical about getting any improvement. However, after about 8 weeks, I began to notice an awakening in my brain. This continued, and by March 2007, I was feeling quite perky. Friends commented on the fact that I had become very chatty and I was also waking early in the morning raring to go, totally unlike my former self. In May 2007, I had another serum 25(OH)D test and the result was 115nmol/L.Another interesting result was my serum triglycerides, something that's usually always higher than desirable. My serum TG was 1.4mmol/L (RR <1.8mmol/L). This was the lowest result since tests began in 2002.
I began to get bored with standing around stark naked in front of a UV lamp for 3 minutes each night and I stopped doing this. Slowly, my brain began to go back to sleep. I couldn't understand why as I thought that 2,000iu/day of Vitamin D3 (10 x RDA) was more than enough. In November 2007, I had another serum 25(OH)D test. When I saw my endocrinologist in December 2007, I was quite shocked to see that the result was now 70nmol/L. I immediately increased my Vitamin D3 intake to 5,000iu/day (25 x RDA) and within 2 weeks, my brain started to wake up again. I will be having another blood test in May 2008.
See also The urgent need to recommend an intake of vitamin D that is effective.
For a list of the top 432 foods highest in Vitamin D, see here. Beware of foods that have been supplemented, as Vitamin D2 may have been used. This is much less effective than Vitamin D3 according to Armas, Hollis and Heaney. Vegetarians & vegans may not want to eat foods containing Vitamin D3 as this is sourced from animals (e.g. the lanolin from a sheep's coat). Eating the Standard English Diet, it is difficult to obtain 5,000iu/day of Vitamin D. The cheapest way to get a lot of it is by going out in the sun in a swimsuit for 20 or so minutes in the middle of the day in Summer & Autumn, which costs absolutely nothing! As Vitamin D is fat-soluble, the body can build up stores to keep it supplied during Winter & Spring.
According to Hyppönen and Power, there is a strong association between decreasing 25(OH)D, increasing BMI (Body Mass Index) and increasing HbA1c (glycosylated haemoglobin). Increasing HbA1c is associated with increasing Relative Risk of mortality, according to Khaw, Wareham, Bingham, Luben, Welch and Day , summarised here.
According to Chiu, Chu, Go and Saad, there is a positive correlation of 25(OH)D concentration with insulin sensitivity and a negative effect of hypovitaminosis D on ß cell function. Subjects with hypovitaminosis D are at higher Relative Risk of Insulin Resistance and The Metabolic Syndrome.
According to Lappe, Travers-Gustafson, Davies, Recker and Heaney, subjects receiving 1400-1500mg/day supplemental calcium and 1100iu/day supplemental Vitamin D3 have a Relative Risk of getting any type of cancer of 0.402 which is equivalent to a 60% reduction in the risk of getting cancer compared to the non-supplementing group. If the first 12 months results are discarded (to exclude any subjects who already had cancer when they started the study), the RR is 0.232 which is equivalent to a 77% reduction in the risk of getting cancer. One wonders what the results would have been if 5,000iu/day of Vitamin D3 had been used. See also Díaz, Paraskeva1, Thomas, Binderup and Hague.
According to Vieth, Kimball, Hu & Walfish as mentioned above, supplementing with 4,000iu/day of Vitamin D3 produces a huge reduction in the "Miserableness Factor" without affecting serum Calcium levels. According to Wilkins, Sheline, Roe, Birge and Morris, Vitamin D deficiency is associated with low mood and worse cognitive performance in older adults. According to Gloth, Alam and Hollis, Improvement in 25(OH) D is significantly associated with improvement in depression scale scores.
According to Forman, Giovannucci, Holmes, Bischoff-Ferrari, Tworoger, Willett and Curhan, plasma 25(OH)D levels are inversely associated with the risk of incident hypertension.
According to Cannell, Vieth, Umhau, Holick, Grant, Madronich, Garland and Giovannucci, Vitamin D deficiency predisposes children to respiratory infections. According to Ginanjar, Sumariyono, Setiati and Setiyohadi, The active form of vitamin D produces and maintains self immunologic tolerance.
According to Dharmarajan, Akula, Kuppachi and Norkus, in the pilot study of older adults with gait imbalance and falls, vitamin D deficiency (< 20ng/mL) is observed in 54% of patients tested.
According to Plotnikoff and Quigley, all patients with persistent, non-specific musculoskeletal pain are at high risk for the consequences of unrecognized and untreated severe hypovitaminosis D. According to Al Faraj and Al Mutairi, Vitamin D deficiency is a major contributor to chronic low back pain in areas where vitamin D deficiency is endemic. According to Gloth, Lindsay, Zelesnick and Greenough, there may be a pain syndrome associated with vitamin D depletion that appears as hyperaesthesia worsened by light, superficial pressure or even small increments of movement.
Inappropriate sun exposure can certainly damage the skin. Chronic overexposure to sun (e.g. farmers and other outdoor workers) causes wrinkly, leathery skin and skin cancers such as Basal Cell Carcinoma & Squamous Cell Carcinoma. These are benign skin cancers which are easily removed and rarely fatal. Acute overexposure to sun (e.g. people getting severe sunburn on foreign holidays) causes the much more serious Malignant Melanoma. This condition, if not caught early enough, has a very high risk of mortality. However, sensible sun exposure has more benefits than hazards. See Does solar exposure, as indicated by the non-melanoma skin cancers, protect from solid cancers: vitamin D as a possible explanation.
It is possible to over-supplement with Vitamin D. According to Vieth, published cases of vitamin D toxicity with hypercalcemia, for which the 25(OH)D concentration and vitamin D dose are known, all involve intakes of >1000μg/day (>40,000iu/day). People suffering from Sarcoidosis, Primary Hyperparathyroidism, a history of Calcium Kidney Stones and Milk-Alkali Syndrome need to be careful with their Vitamin D intake. People prescribed Warfarin also have to be careful, as Warfarin is a Vitamin K antagonist which can result in calcification of tissues.
It's not possible to overdose on Vitamin D by sun exposure as the metabolic processes down-regulate when ~10,000iu has been produced. To find out when the sun is strong enough to produce Vitamin D in your skin, see the Vitamin D Synthesis in Human Skin Calculator.
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