• Bronwyn Carroll

Bioavailable Vitamin D

A potent, bioavailable supplemental form of vitamin D is now available in the form Colcifediol. This new practitioner-only formulation increases vitamin D levels up to three times more efficiently, having a higher rate of intestinal uptake, also bypassing the need for liver conversion.


Cholecalciferol is produced naturally when the skin is exposed to sunlight and is also the form of vitamin D currently found in most supplements. The liver then has to convert cholecalciferol into colcifediol, the form of vitamin D that circulates in the human body. Colcifediol supplements bypass the liver entirely and are easily absorbed straight into the portal vein circulation.


Vitamin D is essential for good health and is required to support healthy bone, muscle, nerves, the immune system and mood. Many health conditions have been associated with low levels of vitamin D, including rickets, osteoporosis, Alzheimer's disease, hypertension, upper respiratory infections and autoimmune disease. Low levels of Vitamin D have also been associated with an increased risk of chronic diseases, including cardiovascular disease, diabetes and certain cancers.

Known as the “sunshine vitamin” ultraviolet (UV) radiation from the sun is necessary for the production of vitamin D in the skin and is the best source of natural vitamin D.

Although general guidelines recommend 15 - 20 minutes in the sun 3-4 days a week to support healthy vitamin D levels, there can be great variation in how much vitamin D the skin makes depending on the amount of skin exposed, skin type, time of day and different seasons.


Very few foods are naturally high sources of vitamin D, with the highest being cod liver oil and fatty fish (salmon, tuna, mackeral and sardines), followed by eggs and some mushrooms in varying amounts. Some foods such as dairy products, are fortified with vitamin D in production, however food alone cannot provide an adequate amount of vitamin D. Most people are reliant on sun exposure to reach recommended levels.


The amount of vitamin D needed per day varies with age and can also be impacted by other factors, such as diet and inadequate sun exposure. In addition certain medical conditions and medications are known to increase the risk of vitamin D deficiency.

Risk Factors for Vitamin D Deficiency

  • Age - with age our skin loses the ability to make vitamin D

  • Mobility - people who spend large amounts of time indoors and are not able to get outside for sun exposure

  • Skin colour - dark-coloured skin is less able to make vitamin D than fair-colored skin.

  • Breast milk - a woman's breast milk only contains a small amount of vitamin D.

  • Malabsorption diseases - diseases that reduce absorption through the intestines such as Celiac disease, Chron's disease and Cystic fibrosis.

  • Weight loss surgeries - weight loss surgeries that reduce the size of the stomach and/or bypasses part of the small intestines, make it very difficult to consume sufficient quantities of certain nutrients, vitamins, and minerals.

  • Obesity - a body mass index greater than 30 is associated with lower vitamin D levels, as fat cells store vitamin D so that it is not released and needs increase.

  • Kidney and liver diseases - reduces the amount of an enzyme needed to change vitamin D to a form that is used in the body.

  • Medications - such as laxatives, steroids, and cholesterol- lowering drugs


Children who are deficient in vitamin D can experience muscle weakness, or sore and painful muscles. Whilst it is rare, a severe deficiency of vitamin D in children causes rickets, which presents as incorrect growth patterns, weakness in muscles, pain in the bones and deformities in joints. Deficiency, or low levels of vitamin D are not always quite as obvious in adults.


Signs & Symptoms of Vitamin D deficiency

  • Frequent infections or illnesses

  • Fatigue and muscle weakness, aches and cramps

  • Bone and joint pain

  • Fractures

  • Mood changes, especially depression

  • Slow wound healing

  • Deformities of the teeth in children

  • Developmental delays in children


Being a fat soluble vitamin, the body is able to store vitamin D, and can be toxic when higher levels of supplementation are taken without monitoring. Interestingly, you cannot get too much vitamin D from the sun. If you are unsure about your vitamin D levels, a GP can order a blood test that can accurately measure your levels.

If you have low vitamin D levels, or any other concerns regarding your vitamin D health status, contact me, or make an appointment to review your risk factors and discuss supplementation.


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