92. Is Vitamin D the Answer to Diabetes?

Compared with the population as a whole, those with a high Vitamin D status have almost 90% less diabetes. This is the remarkable result obtained in a study initiated by Grassroots Health, which is dedicated to understanding the role of Vitamin D and promoting its benefits (1). It is responsible for D*action, which is an international public health project to solve the vitamin D deficiency epidemic. It was founded by Carole Baggerley, who had successfully conquered breast cancer, which she largely attributed to Vitamin D.

This particular study was conducted by Dr Cedric Garland of the University of California at San Diego. Dr Garland is a respected academic who along with his brother Frank (now deceased) discovered the link between exposure to sunshine and the incidence of bowel cancer by collecting and analysing data from the various states in the USA. This then focused attention on the role of Vitamin D and stimulated the recent research conducted over the past 30 years or so, which has demonstrated that most people do not have sufficient and would greatly improve their health by raising the level of Vitamin D in their bodies.

The results are shown in Table 1. NHANES, is the National Health and Nutrition Examination Survey, which is genuinely representative of the US population. It is evident that the much higher level of Vitamin in the Grassroots participants is more than double that of the NHANES participants.

Table 1. Incidence of diabetes and serum levels of Vitamin D in US and in Grassroots populations (2)

Diabetes incidence, per 1000 person years8.50.9
Average Vitamin D serum levels, ng/ml (nmol/l)22(55)53(130)


There is a discussion between Carole Baggerley and Cedric Garland on You Tube which is well worth watching (3).


While these are preliminary results they are nevertheless extremely significant and their importance cannot be underestimated. In particular, the relatively high levels in the serum of those with a low incidence of diabetes must be recognised. Dr Garland emphasised that if the serum level can be pushed up about 60 ng/ml (150 nmol/L) that diabetes would be virtually eliminated and that this could be achieved very quickly, possibly within a year. Furthermore it applies to both Type 1 and Type 2 diabetes. There is absolutely no danger associated with daily doses of up to 10,000 IU.

Although the Scientific Advisory Committee on Nutrition(SACN) is currently considering Vitamin D, an update was published in 2007 (4). At that time an adequate serum concentration was considered to be 25 nmol/l. This is much lower than the average NHANES value. However it also recognised that some researchers advocated values higher than 75 nmol/l, SACN did not make any recommendation. The results of the Grassroots study demonstrate that even higher values must be reached if the maximum benefits are to be achieved.

Vitamin D can be produced in the body as a result of exposure to sunlight. But this will only happen if people spend time outside during the summer months and allow the sunlight to contact the skin. However in the typical climate of the British Isles, we do not always have enough sunshine at the height of the summer and certainly not during the rest of the year. The quantities present in foods are not capable of supplying what is actually needed. Hence supplements must be taken.

The update confirmed the Dietary Reference Value for pregnant and breast feeding women as 400 International Units (IU). This is just far too low. Much higher intakes of the order of 5,000 IU or even more must be taken to achieve the levels in the blood to control diabetes.

This investigation by Grassroots is just another one of many studies which confirms the crucial importance of Vitamin D as a critical and essential nutrient. In addition it is now evident that the previous thinking on the requirements was based primarily on the prevention of rickets. The recent improvement in our understanding makes it very clear that Vitamin D has a key role in many different organs and that the requirement to satisfy these functions fully is considerably higher than originally envisaged.

Other examples of the benefits to health of Vitamin D are:

  • Participants in trial with a supplement of 1100 IU Vitamin D plus calcium achieved a reduction of 77% in the incidence of breast cancer as compared with those taking a placebo (5)
  • In a study in south west Germany involving over 3,000 men and women who were high risk for heart disease it was found that those with a blood serum level of >75 nmol/L had one quarter the death rate of those whose level was  <25 nmol/L. It was noteworthy that despite the very different death rates the cholesterol values and the BMIs were virtually the same (6)
  • In pregnant women carrying twins it was found that those with serum Vitamin D of >75 nmol/L had a 60% reduction in the odds of pre-term birth compared those whose serum Vitamin D was <75 nmol/L (7).

For those interested in a comprehensive account of the Vitamin D story, I can recommend “The Vitamin D Solution” by Michael Holick (8).

From a public health perspective, there is no question that diabetes is the big issue. The fact that the incidence has doubled in the last 15 years and is continuing to rise shows very clearly it is a major threat. Many people are condemned to a miserable existence possibly having to lose limbs by amputation.  Those with diabetes have a much increased risk of developing various cancers, heart disease and Alzheimer’s Disease. Despite all the efforts and expenditure, progress in controlling the diabetes has been disappointing (9). The existing strategies are obviously not working.

The information here provides convincing evidence that most people do not have anything like enough Vitamin D in their system. I realize that there will still be calls for more research before policies can be devised. However the position is absolutely dire and if not addressed immediately will undoubtedly continue to get even worse. Encouraging everyone to take a supplement of Vitamin D would pay rapid dividends. For a start, a daily intake of 1000 IU would make a huge difference. Even if this is done on a pilot scale initially, almost certainly benefits would be observed within a relatively short time-frame. Ideally a programme of monitoring is needed but if necessary could be introduced at a later stage. The benefits would be huge, the costs relatively small and the risks of harm negligible. If this approach is combined with the recent SACN proposal to reduce sugar then we really could crack the diabetes problem. As this is just the tip of the iceberg, we might also expect progress with respect to heart disease, cancers and Alzheimer’s. A “no-brainer” if ever there was one.

I would not be surprised if such an initiative gets the “thumbs down” from the “great and the good” in the medical and public health professions. Nevertheless the time bomb is ticking away and we have the means to address it. It remains to be seen if there is any politician with the confidence and determination to take on the vested interests and the dinosaurs. I wish I could be more hopeful!!!


  1. http://www.grassrootshealth.net/
  2. http://grassrootshealth.net/index.php?option=com_content&view=article&id=193
  3. http://www.youtube.com/watch?v=Cakw11ufk9A&feature=youtu.be
  4. http://www.sacn.gov.uk/pdfs/sacn_position_vitamin_d_2007_05_07.pdf
  5. http://ajcn.nutrition.org/content/85/6/1586.full.pdf
  6. G N Thomas et al (2012) Diabetes Care 35 (5) pp1158-1164
  7. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3706065/
  8. M F Holick (2010) “The Vitamin D Solution: A 3-Step Strategy to Cure Our Most Common Health Problems” Plume (Penguin) New York
  9. Remy Boussageon et al (2011) http://www.bmj.com/content/343/bmj.d4169.pdf%2Bhtml
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