By naturopath Margaret Jasinska

If so, here are 12 possible explanations.

Vitamin D is a critical nutrient that benefits your health in numerous ways. Your body can obtain it through sunshine exposure, foods or supplements. Have you had a vitamin D blood test and discovered you are low despite sun exposure or supplements? This is common and there are several explanations.

Reasons you may be low in vitamin D:

• Insufficient skin exposed to the sun. Just your hands and face are not enough. You need to expose enough of your skin in order to manufacture sufficient vitamin D. Ideally your arms, legs and back, such as being in your underwear in your backyard.
• You’re outside at the wrong time of day. Vitamin D is manufactured in your body from UVB rays. They are generally strongest between 10am and 2pm. It is still healthy to be outdoors during sunrise and sunset, you just can’t make vitamin D at those times.
• Sunscreen blocks around 95 to 98 percent of UVB rays from penetrating your skin, leaving you unable to manufacture vitamin D. Fake tan also inhibits penetration of UVB rays.
• You’re not spending long enough in the sun. The lighter your skin tone, the less time you need out in the sun to manufacture vitamin D, and of course the more quickly your skin can start to burn. For vary fair skin tones, 15 minutes may be enough. People with very dark skin may need more than an hour and this may not be practical.
• You are low in magnesium. If you are magnesium deficient, you cannot utilise the vitamin D in your body. It remains trapped in storage, and unavailable in your bloodstream. Many people aren’t getting optimal levels of magnesium in their diet. Research from a review published in The Journal of the American Osteopathic Association showed that people may be taking vitamin D supplements but don’t realise how it gets metabolised. Without magnesium, Vitamin D is not really useful.
• If you are overweight you may have plenty of vitamin D in your fat stores but not enough in your bloodstream where you need it. Vitamin D is fat soluble, so it tends to get trapped in the body fat of overweight people.
• Inflammation can block vitamin D metabolism. Chronic inflammation can be caused by autoimmune disease, allergies or infections. Chronic infections such as Lyme disease, Epstein Barr virus, parasites or mold toxicity can be responsible for long term low vitamin D.
• Poor fat digestion and absorption can be responsible for low vitamin D. This can be due to fatty liver, gallbladder problems resulting in insufficient bile secretion, or in people who have had their gallbladder removed. Insufficient digestive enzymes, leaky gut, small intestinal bacterial overgrowth and dysbiosis can all lead to poor fat digestion. Gut Health powder helps to improve the lining of the digestive tract by healing leaky gut.
• If you are on a low fat diet you may not absorb vitamin D supplements well because vitamin D is fat soluble. It needs to be taken with a meal that contains fat otherwise may not get absorbed properly.
• Having low cholesterol can inhibit your body from producing vitamin D when exposed to the sun because it’s the cholesterol in your skin that gets converted into vitamin D. This can be a problem in people taking cholesterol lowering drugs and those with naturally low cholesterol.
• Impaired liver or kidney health. Vitamin D production from sunshine occurs in the skin, liver and kidneys. If the health of those organs is compromised, vitamin D production may be insufficient.
• The skin of elderly individuals doesn’t manufacture vitamin D from sunshine as well as in younger people.

The best way to know exactly how much vitamin D you need is to ask your doctor for a blood test. An ideal level is between 100 and 150nmol/L. You cannot get excessively high vitamin D from sunshine but you could from supplements, although this is uncommon. Sunshine is good for your health but please avoid getting sunburnt. Know how much sun your individual skin can tolerate safely.