Vitamin D Research
Vitamin D Deficiency, Supplementation and a Case Report
Vit D has been a hot topic over the last couple of years and is somewhat of a buzzword in the world of nutrition and health at the minute; The first time we wrote something on Vitamin D was in 2009 on Mac-Nutrition 1.0 about Vitamin D and immune function. Since then it has been a real area of interest so we thought we would share some interesting information, research and reports on it.
First up, a Case Report of two men who consumed approximately 1,700,000IU of Vitamin D3 per day (PDF) for over 7 months! The consequences?
right-sided flank pain, conjunctivitis, anorexia, fever, chills, increased thirst, and vomiting, weight loss and acute renal failure.
The 'normal' range for blood Vit D levels (25-hydroxyvitamin D [25(OH)D]) is 20–80nmol/L, in this case it was 1555-3700nmol/L!! In this instance, the men had been unknowingly using table sugar that was contaminated with super high levels of Vitamin D.
For anyone wanting to supplement with Vitamin D, here is a high quality, good value for money product: Buy your Vitamin D3. The dosage you use depends on a number of factors, not least your skin colour. We wrote an article on this titled: Vitamin D synthesis depends on skin pigmentation
The best idea is always to get your Vitamin D levels tested so that you can supplement appropriately. You can of course go to your GP and request the test; over 50% of our clients have been able to get this done however some have been refused and instead have had to pay for it themselves either through private healthcare or via this scheme: vitamindtest.org.uk (If you use this scheme and get your levels tested, please leave a comment below with your results!)
Insulin resistance, diabetes and related disorders
This study concluded that Vitamin D "deficiency can result in insulin resistance and diabetes" – Vitamin D Deficiency and Insulin Resistance in Normal and Type 2 Diabetes Subjects
The effect of vitamin D on insulin resistance in patients with type 2 diabetes [PDF] – 50,000IU per week for 8 weeks resulted in significant improvements in serum FPG, insulin and HOMA-IR after treatment.
Therapeutic implications of vitamin D and calcium in overweight women with polycystic ovary syndrome – This study used a daily Vitamin D3 dose of 3533IU in 5 participants and 8533 IU in the other 7 as well as 530mg of Calcium. It found improved androgen (normalizing of testosterone) and blood pressure profiles after 3 months.
Role in Athletic Populations
Vitamin D deficient athletes may be at an increased risk for stress fractures, respiratory infections & muscle injuries- The Effects of Vit D Deficiency in Athletes
Improving the vitamin d status of vitamin d deficient adults is associated with improved mitochondrial oxidative function in skeletal muscle – Vitamin D supplementation augments muscle mitochondrial maximal oxidative phosphorylation after exercise in vitamin D-deficient individuals experiencing fatigue. This is the first demonstrated link between vitamin D and the mitochondria in human skeletal muscle.
The effects of Vit D3 supplementation on serum total 25[OH]D concentration and physical performance: a randomised dose–response study – Increasing serum 25[OH]D had no significant effect on any physical performance parameter – 1-RM bench press and leg press and vertical jump height.
Role in a variety of disease states
An interesting review paper titled: Can we prevent or treat multiple sclerosis by individualised Vit D supply? – Click here to download the PDF
A review paper exploring the role of Vit D in multiple sclerosis – The case for vitamin D supplementation in multiple sclerosis
An interesting review looking at the paradox that UV light damages skin cells but Vitamin D is produced in the skin from the sun and there are signaling pathways that show a vitamin D-induced protection of skin cells from UV – Vitamin D & Death by Sunshine [PDF]
Vitamin D deficiency and Alzheimer's disease (AD) have shown to be associated and supplements appear to have a beneficial clinical effect on AD via a number of mechanisms – The Role of Vit D in Alzheimer’s disease: Possible Genetic and Cell Signaling Mechanisms
In asthmatic children treated with inhaled corticosteroids, vitamin D deficiency is associated with poorer lung function than children with vitamin D insufficiency or sufficiency.
Studies giving indications of appropriate dosages
Vitamin D Status and Supplementation in Elite Irish Athletes – Wintertime supplementation (5000IU/day) significantly increased Vitamin D levels, & corrected any insufficiencies/deficiencies. Vitamin D levels significantly decreased in those that did not receive a vitamin D supplement, with 74% of athletes classed as vitamin D insufficient/deficient after winter, compared to only 35% at baseline.
A really interesting double blind, placebo controlled RCT on Vit D supplementation – A Randomised, Double-Blinded, Placebo-Controlled, Parallel Study of Vit D3 Supplementation with Different Schemes Based on Multiples of 25,000 IU Doses [PDF]
The effects of Vit D3 supplementation on serum total 25[OH]D concentration and physical performance: a randomised dose–response study – 20000IU or 40000IU/week for 12 weeks. 57% were deficient at baseline (mean = 51nmol/l). Following 6 and 12 weeks supplementation with 20000IU (79 & 85nmol/l, respectively) or 40000IU (98 & 91nmol/l, respectively), serum vitamin D concentrations increased in all participants.
Body Fat and Obesity related complications
Supplementation with 7000IU/day for 26 weeks in obese individuals did not improve body composition (DXA; subcutaneous and visceral adipose tissue), intrahepatic and intramyocellular lipids (MRI and MRS), insulin resistance (HOMA-IR), blood pressure, plasma lipids and circulating inflammatory markers.
Effects of vitamin D supplementation on body fat accumulation, inflammation, and metabolic risk factors in obese adults with low vitamin D levels — Results from a randomized trial