Healthy Diet Essentials : Vitamin D

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 homoeostasis in bones and that a lack of it caused only Rickets. Recent research has shown that not only is Vitamin D involved in a whole host of bodily processes, but also that an insufficiency in it is very common, leading to a whole host of degenerative diseases.

What is Vitamin D?
There's a good overview on Vitamin D here.
Here's a presentation called Vitamin D deficiency: The Cause of Everything?
Here's a presentation called Vitamin D and Prevention of Chronic Diseases.
See also Use of Vitamin D in Clinical Practice and Vitamins D and K as Pleiotropic Nutrients.

How common is Vitamin D deficiency?
According to Hyppönen and 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 less than 75nmol/L in Summer & Autumn, and 87.1% had serum 25(OH)D of less than 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 50-200 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 and 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 TGs were 1.4mmol/L (RR less than 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. In May 2008, serum 25(OH)D was 173nmol/L and in September 2008 it was 163nmol/L. I'm still taking 5,000iu/day.

See also The urgent need to recommend an intake of vitamin D that is effective.

What foods contain it?
For a list of the foods highest in Vitamin D, see here. Beware of foods that have been supplemented, as Vitamin D2 may have been used. This is less effective than Vitamin D3 according to Armas, Hollis and Heaney. Vegetarians and 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 and Autumn, which costs absolutely nothing. As Vitamin D is fat-soluble, the body can build up stores to keep itself supplied during Winter and Spring.

Vitamin D deficiency, Insulin Resistance and The Metabolic Syndrome and Type 2 Diabetes
According to Hyppönen and Power, there is a strong association between decreasing 25(OH)D, increasing BMI (Body Mass Index) and increasing HbA1c (glycated haemoglobin).
According to Khaw, Wareham, Bingham, Luben, Welch and Day, increasing HbA1c is associated with increasing Relative Risk of mortality, 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.

In January 2003, I had impaired Glucose Tolerance (fasting serum glucose = 6.8mmol/L and 2 hours post-75g glucose load serum glucose = 8.7mmol/L). A sandwich used to send me to sleep.
By September 2008, I had normal Glucose Tolerance (fasting serum glucose = 5.0mmol/L and 2 hours post-75g glucose load serum glucose = 3.7mmol/L). I also no longer suffered from hyperinsulinaemic sleeps. Result!

Vitamin D deficiency and Cancer
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. I wonder what the result would have been had 5,000iu/day of Vitamin D3 been used.
See also Diaz, Paraskeva, Thomas, Binderup and Hague.

Vitamin D deficiency and Mental function
According to Vieth, Kimball, Hu and Walfish as mentioned above, supplementing with 4,000iu/day of Vitamin D3 produces a large 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 in a group of 15 subjects with SAD.
According to Cherniack, Troen, Florez, Roos and Levis, Hypovitaminosis D is prevalent among older adults, and several studies suggest an association between hypovitaminosis D and basic and executive cognitive functions, depression, bipolar disorder, and schizophrenia.

Vitamin D deficiency and High Blood Pressure
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.

Vitamin D deficiency and the Immune System
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 Setiyohad i, The active form of vitamin D produces and maintains self immunologic tolerance.

Vitamin D Deficiency and Falls
According to Dharmarajan, Akula, Kuppachi and Norkus, in the pilot study of older adults with gait imbalance and falls, vitamin D deficiency was observed in 54% of patients tested and previously unrecognised.

Vitamin D Deficiency and Chronic Pain
According to Plotnikoff and Quigley, all patients with persistent, non-specific musculoskeletal pain are at high risk for the consequences of unrecognised 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.

But doesn't the sun damage the skin and cause skin cancer?
Inappropriate sun exposure can certainly damage the skin. Chronic overexposure to the sun (e.g. farmers and other outdoor workers) causes wrinkly, leathery skin and skin cancers such as Basal Cell Carcinoma and Squamous Cell Carcinoma. These are benign skin cancers which are easily removed and rarely fatal. Acute overexposure to the 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. EDIT: See also Is Vitamin D Shooting Me in the Foot?

Is it possible to get too much Vitamin D?
It is possible to overdose with Vitamin D by supplementation. According to Vieth, published cases of vitamin D toxicity with hypercalcaemia, for which the 25(OH)D concentration and vitamin D dose are known, all involve intakes of greater than 40,000iu/day. See also Pharmacokinetics of vitamin D toxicity.
People suffering from Sarcoidosis, Primary Hyperparathyroidism, a history of Calcium Kidney Stones and Milk-Alkali Syndrome need to consult their GP before supplementing with Vitamin D. People prescribed Warfarin also need to be careful, as Warfarin is a Vitamin K antagonist, which can result in calcification of tissues.

It isn't possible to overdose 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.

EDIT: Insufficient Vitamin A can result in Vitamin D toxicity. See Is Vitamin D Safe? Still Depends on Vitamins A and K! Testimonials and a Human Study.

EDIT: Vitamins A & D are synergistic, not antagonistic. See New Evidence of Synergy Between Vitamins A and D: Protection Against Autoimmune Diseases.

I've found a cheap source of 5,000iu Vitamin D3 gelcaps. See http://www.iherb.com/Vitamin-D3-5-000-IU-360-Softgels/18335 That's a 1 year supply for about £10. First-time buyers can use discount code NIG935 to get $5 off their first order. Standard shipping is $4.

10,000iu Vitamin D3 gelcaps are also available. See http://www.iherb.com/Healthy-Origins-Vitamin-D3-10-000-IU-360-Softgels/21298

EDIT: See Cheapest Vitamin D3 yet. That's a 1 year supply for about £7.50.

Addendum:- Editorials, meta-studies and human Randomised Controlled Trials on Vitamin D and Vitamin D3 over the period 2005 to present.

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