Vitamin D Response: Did You Get Enough Sun Today?

• There have been a number of studies which have linked deficiency in this nutrient to health problems such as diabetes, heart disease and certain types of cancer.
• For those who are not getting enough Vitamin D, diet and lack of sunlight may not be the sole cause. For some people, genetic factors may be at play.
• We also know that people with darker skin colour tend to make less Vitamin D than those with lighter skin colour.
• While we can’t change our genetics, if you know that you’re genetically at risk to be Vitamin D deficient, Health Canada recommends that adults get 8,000 IU of the Vitamin per day.

You’ve probably heard about the importance of getting enough Vitamin D. For years we were warned about getting too much sun because of the risk of skin cancer, but now we’re being told to make sure we get enough sunlight so that our bodies can absorb the all-important Vitamin D.

There have been a number of studies which have linked deficiency in this nutrient to health problems such as diabetes, heart disease and certain types of cancer.^[i] Our bodies produce Vitamin D primarily from exposure to the sun, as there are not very many foods that contain it. Vitamin D plays many important roles in the body including aiding the absorption of calcium, modulation of cell growth and reduction of inflammation. In children, it prevents rickets, and in older adults, it protects against osteoporosis.^[ii]

GENETICS AND VITAMIN D

What you may not realize, however, is that for those who are not getting enough Vitamin D, diet and lack of sunlight may not be the sole cause. For some people, genetic factors may be at play.

Studies have shown that there are certain genetic variants which can make it more likely that a person will be deficient in Vitamin D. One such study which took place in Denmark found that additional sunlight and diets fortified with the Vitamin were less likely to have an affect on those with certain genetic variants. The PhD study showed that two genes in particular – CYP2R1 and GC – influenced levels of Vitamin D in the blood. ^[iii]

Other studies, however, have shown that there are several other genes that influence the body’s response to Vitamin D.^[iv]

We also know that people with darker skin colour tend to make less Vitamin D than those with lighter skin colour.^[v] This is likely due to the fact that those with dark skin have traditionally lived in hotter and sunnier geographic locations, and therefore required more protection from the sun. On the other hand, those with very light skin traditionally have lived in colder climates with less sunlight and needed to make Vitamin D with the limited amount of sun exposure that they had.

WHAT YOU CAN DO

While we can’t change our genetics, if you know that you’re genetically at risk to be Vitamin D deficient, Health Canada recommends that adults get 1,000 mg of the Vitamin per day. ^[vi] Sources of Vitamin D include sunlight, as well as foods such as dairy products, eggs and fish like tuna, herring and salmon. If you are concerned that you are not getting enough Vitamin D through these sources, you might also consider taking a supplement.

Although your genetic scores are not meant to be medical advice, they can give you insight into some areas you may not have considered. If you discover that you are genetically predisposed to low Vitamin D response, consider talking to your doctor or dietitian about how to keep your levels up.

[i] https://www.webmd.com/vitamins-and-supplements/news/20100609/genes-may-play-arole-in-vitamin-d-deficiency#1

[ii] https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/

[iii] https://www.sciencedaily.com/releases/2015/12/151202084455.htm

[iv] https://www.vitamindwiki.com/Vitamin+D+levels+are+strongly+associated+with+genes:+overview+of+twin+studies+%E2%80%93+Nov+2012

[v] http://www.ctvnews.ca/skin-colour-linked-to-vitamin-d-deficiency-1.268118

[vi] https://www.canada.ca/en/health-canada/services/food-nutrition/healthy-eating/vitamins-minerals/vitamin-calcium-updated-dietary-reference-intakes-nutrition.html