We’re here to give the humble Vitamin D the praise it deserves…
Last night I saw a client who had quite a number of questions about the wonderful Vitamin D. Many of us are unaware of the huge health benefits that this humble vitamin offers. I’m here to help shoot the science and give Vit D the respect and praise it deserves.
Vitamin D has many functions, it is best known for its role in strengthening our bones, through facilitating the absorption of calcium and phosphorus. Because this function is well known I am not going to preach that. I’m going to focus more on the underground Vitamin D benefits. Vitamin D is a steroid hormone and plays a vital role in our immune function and the growth and development of cells. It’s a precursor for multiple biochemical pathways and controls the expression of over 1000 genes in our bodies! It helps to protect us against a range of different chronic conditions.
I’m a big fan of the sun (why do you have to be so loooong, winter?). One reason for this? Vitamin D is produced by the sunshine! The sun’s ultraviolet B rays interact with a protein in our skin, converting it into vitamin D3. This is the active form of vitamin D. Spending some time in the sunshine each day will help maintain optimal levels of vitamin D. But before you head out to soak up the sun (good luck if you live in Melbourne like we do!), there are a few things to be aware of….
1. Sun protection
Sunscreen protects our skin so well from the UV B rays that it inhibits the pathway that produces Vitamin D. Now this is where is gets tricky… I’m not telling you to not wear sunscreen. , We need it (some desperately! We see you Ed Sheeran) to reduce our risk of skin cancer and premature aging. For most people, adequate vitamin D levels are reached through regular incidental exposure to the sun, e.g. walking to the train station on the way to work or taking the dog for a walk.
Another factor that influences the amount of Vitamin D our bodies produces is melanin. Melanin is a dark brown to black pigment in our hair, skin, and iris of the eye. It’s responsible for tanning of skin exposed to sunlight. In most cases, the darker your skin is, the more melanin you have. Generally, people with darker skin need to be outside for longer to achieve desired levels of Vitamin D than those with pale or fair skin.
Age is another variable which influences our ability to produce Vitamin D. As we age, our bodies become less efficient at producing Vitamin D. If you aren’t sure if you’re getting enough, we recommend getting your serum levels tested through a blood test before you commence supplementation.
4. Body fat
The amount of body fat we have also influences our Vitamin D status. Being overweight reduces the bioavailability of Vitamin D in the body. This is because Vitamin D is a fat soluble vitamin and is stored in our fat cells, sothe more fat you have the more Vitamin D that is stored in your fat rather than circulating in the bloodstream. So if we want to benefit from all the amazing health benefits of Vitamin D, there’s extra incentive for us all to achieve and maintain a healthy weight!
Our favourite subject. Mmmm. Unfortunately, vitamin D is fussy and only small amounts of vitamin D are found in a few foods. This makes it nearly impossible to get the amount you need from food alone.
We soak up the sun just for you!
What about the health benefits of vitamin D? I’m so glad you asked! I could be here all day if I wanted to cover all the wonderful health benefits of our friend Vitamin D. But I’ll rein it in. We’re all busy. A few of my favourites are highlighted below…
There are several studies which have suggested that people with higher levels of Vitamin D concentrations in their blood have reduced risk of developing colorectal cancer and that achieving and maintaining adequate Vitamin D levels may improve survival rate of patients with colorectal cancer. Similar pleasing results have been found in the the breast cancer population, women with higher Vitamin D levels were found to have a 16% reduced risk of developing breast cancer. Lots of research is happening in other areas, but we’re suspicious the benefits will be consistent in other cancer types.
Type 2 Diabetes
In healthy people, adequate levels of serum vitamin D helps to improve insulin sensitivity and pancreatic function. In contrast, those with vitamin D deficiency are more likely to experience impaired glucose tolerance and insulin resistance. Other studies have shown that individuals with pre-diabetes (at high risk of developing type 2 diabetes), had lower concentrations of serum Vitamin D compared to healthy subjects. The science says that those with higher levels of vitamin D are approximately 20% less likely to develop type 2 diabetes and 15% less likely to develop metabolic syndrome (14% lower risk) than those with lower levels.
Cardiovascular disease (CVD)
Adequate serum vitamin D levels can reduce the risk of hypertension contributing to CVD including heart attack and stroke. There are several trials underway exploring the effect of vitamin D supplementation on CVD, so watch this space!
Autoimmune conditions occur when the body elicits an immune mediated response against its own tissues or organs, mistaking it for a foreign body. Lower levels of circulating vitamin D have been reported in people with autoimmune conditions such as type 1 diabetes, multiple sclerosis, and rheumatoid arthritis. We suspect that correcting vitamin D deficient and maintaining sufficient serum levels could possibly help the risk of developing such autoimmune conditions.
Vitamin D is crucial for the maintenance of our bone health through and has also shown to be beneficial in reducing the risk of certain cancers, autoimmune conditions and cardiovascular disease.
If you think you may need a vitamin D supplement, speak to us first and arrange a blood test through your GP or specialist. The Australian dose recommendations are 200-600 IU per day (The Institute of Medicine for Americans recommends 600 -1000 IU per day). Depending on your levels, many need much more than this – speak to your GP about a test, and then us about getting into the optimum range.
Depending on you age, skin colour and where you live in the world your vitamin D needs may differ. Spend just a little time in the sun to top up your vitamin D levels and include oily fish and eggs in your diet regularly. And if you’re not sure you’re getting enough, make an appointment with us or your GP to discuss the most suitable supplement for you.
T A I L O R Y O U R P L A T E | B U I L D Y O U R B E S T Y O U
Accredited Practising Dietitian
- Yin L, Ordonez-Mena JM, Chen T, Schottker B, Arndt V, Brenner H. Circulating 25-hydroxyvitamin D serum concentration and total cancer incidence and mortality: a systematic review and meta-analysis. Prev Med. 2013;57(6):753-764.
- 98. Ma Y, Zhang P, Wang F, Yang J, Liu Z, Qin H. Association between vitamin D and risk of colorectal cancer: a systematic review of prospective studies. J Clin Oncol. 2011;29(28):3775-3782.
- 99. Touvier M, Chan DS, Lau R, et al. Meta-analyses of vitamin D intake, 25-hydroxyvitamin D status, vitamin D receptor polymorphisms, and colorectal cancer risk. Cancer Epidemiol Biomarkers Prev. 2011;20(5):1003-1016.
- 108. Maalmi H, Ordonez-Mena JM, Schottker B, Brenner H. Serum 25-hydroxyvitamin D levels and survival in colorectal and breast cancer patients: Systematic review and meta-analysis of prospective cohort studies. 2014;50(8):1510-1521.
- Wang D, Velez de-la-Paz OI, Zhai JX, Liu DW. Serum 25-hydroxyvitamin D and breast cancer risk: a meta-analysis of prospective studies. Tumour Biol. 2013;34(6):3509-3517.
- Chiu KC, Chu A, Go VL, Saad MF. Hypovitaminosis D is associated with insulin resistance and beta cell dysfunction. Am J Clin Nutr. 2004;79(5):820-825.
- Shankar A, Sabanayagam C, Kalidindi S. Serum 25-hydroxyvitamin D levels and prediabetes among subjects free of diabetes. Diabetes Care. 2011;34(5):1114-1119.
- Khan H, Kunutsor S, Franco OH, Chowdhury R. Vitamin D, type 2 diabetes and other metabolic outcomes: a systematic review and meta-analysis of prospective studies. Proc Nutr Soc. 2013;72(1):89-97.
- Kunutsor SK, Apekey TA, Steur M. Vitamin D and risk of future hypertension: meta-analysis of 283,537 participants. Eur J Epidemiol. 2013;28(3):205-221.
- Al Mheid I, Patel R, Murrow J, et al. Vitamin D status is associated with arterial stiffness and vascular dysfunction in healthy humans. J Am Coll Cardiol. 2011;58(2):186-192.
- Littorin B, Blom P, Scholin A, et al. Lower levels of plasma 25-hydroxyvitamin D among young adults at diagnosis of autoimmune type 1 diabetes compared with control subjects: results from the nationwide Diabetes Incidence Study in Sweden (DISS). Diabetologia. 2006;49(12):2847-2852.
- Sotirchos ES, Bhargava P, Eckstein C, et al. Safety and immunologic effects of high- vs low-dose cholecalciferol in multiple sclerosis. Neurology. 2016;86(4):382-390.
- Antico A, Tampoia M, Tozzoli R, Bizzaro N. Can supplementation with vitamin D reduce the risk or modify the course of autoimmune diseases? A systematic review of the literature. Autoimmun Rev. 2012;12(2):127-136.