Vitamin D Misconceptions

As I sit here in the sunshine with Kevin I can’t help but think about the common misconceptions that surround Vitamin D. One of the main culprits being you only need to spend 10 - 20 minutes a day in the sunshine to receive adequate amounts of Vitamin D. Almost 50% of Australian adults remain deficient. If it was as simple as sun exposure to boost our vitamin D levels than why is almost half the population deficient?

Vitamin D is essential for:

  • Calcium and phosphorus absorption. Without vitamin D, only 10–15% of dietary calcium and about 60% of phosphorus are actually absorbed.

And can be found helpful in the treatment of:

  • Depression

  • Autoimmune disease

  • Heart disease

  • Hypertension

  • Obesity

  • Type 2 diabetes

  • Osteopenia and osteoporosis

Factors affecting Vitamin D absorption:

Obtaining sufficient vitamin D from natural food sources alone is difficult and exposure to some sunlight is essential for maintaining a healthy vitamin D status.  Sun induced vitamin D synthesis is greatly influenced by season, time of day, latitude, altitude, air pollution, skin pigmentation, sunscreen use, passing through glass and plastic, and ageing which is why sitting in the sun for 10 - 30 minutes a day just won’t cut it for everyone.

  • Latitude also has a dramatic influence on Vitamin D levels and reports have shown countries near to the equator receive more sunlight all year round compare with those far from the equator.

  • Wearing a sunscreen with a sun protection factor of 30 reduces vitamin D synthesis in the skin by more than 95%.

  • People with a naturally dark skin tone have natural sun protection and require at least three to five times longer exposure to make the same amount of vitamin D as a person with a white skin tone.

  • Older adults are at high risk of developing vitamin D insufficiency because of aging. Their skin cannot synthesise vitamin D as efficiently.

  • if you have a disability or a disease that affects vitamin D metabolism, such as end stage liver disease, renal disease and cystic fibrosis, coeliac disease and inflammatory bowel disease.

  • For breastfed infants Vitamin D requirements cannot ordinarily be met by human milk alone. Vitamin D content of human milk is related to the mother's vitamin D status; so mothers who supplement with high doses of vitamin D may have high levels of vitamin D in their milk which will obviously benefit the infant greatly.

  • Vitamin D is fat soluble, therefore it requires some dietary fat in the gut for absorption. If you have a reduced ability to absorb dietary fat then you may require vitamin D supplements.

  • Obese people (BMI greater than 30) may need a much greater intake of vitamin D. Larger amounts of visceral fat captures more of the vitamin and alter its release into the circulation

Best time for Vitamin D Exposure in Australia:

Firstly vitamin D can be stored in the body for months so you can ‘stock up’ during Summer to help keep same as a reserve in Winter. And remember these below guidelines will depend greatly on your skin colour. The lighter your skin the less time you may need in the sun.

  • In January, 2 to 14 minutes of sun four times per week between 10am and 3pm will give fair-skinned people with 15% of the body exposed the recommended amount of Vitamin D.

  • From October to March, 10 to 15 minutes of unprotected sun exposure of the face, arms and hands before 10am or after 3pm, three to four times a week, will give you enough Vitamin D without skin damage.

  • However, southern states especially in winter. You'll need longer periods of exposure or more flesh exposed to the sun.

  • From April to September in Melbourne and Hobart you may actually need short periods of exposure in peak UV times ie 10am to 3pm to get enough vitamin D.

  • From June to July in Sydney and Adelaide you may actually need short periods of exposure in peak UV times ie 10am to 3pm to get enough vitamin D.

I hope this has helped clarify Vitamin D for you particularly as we come into the Winer months. Remember I can’t give any nutritional advice via email but feel free to comment below or drop me a line if you have any more questions and I will do my best to respond.

S xx



References:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3897598/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3356951/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5986441/