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Guidelines and vitamin D status
The Zinzino vitamin D guidelines
After extensive work and reviewing of the most up-to-date scientific literature and checking the world’s leading authorities in the area of vitamin D, we finally developed the Zinzino guidelines for all individuals around the globe. It is provided as a self-awareness tool for your convenience but is not intended to overrule any local regulation.
| Zinzino guidelines | ng/mL | nmol/L |
| Critical Low | < 8 | < 20 |
| Deficient/Insufficient | 9-19 | 21-49 |
| Sufficient/Optimal | 20-49 | 50-124 |
| Elevated | 50-59 | 125-149 |
| High | 60-79 | 150-199 |
| Very High | 80-160 | 200-399 |
Example of global guidelines
According to the National Institutes of Health (USA), the relationships between serum 25(OH)D concentration and health are as follows:
| General Guidelines | ng/mL | nmol/L |
| Deficiency | < 12 | < 30 |
| Inadequate | 12 to <20 | 30 to <50 |
| Adequate | ≥ 20 | ≥ 50 |
| Potential adverse effects | > 50 | > 125 |
Similarly, in the UK, vitamin D deficiency is defined as less than 25 nmol/L and associated with rickets and osteomalacia.
Values between 25-30 nmol/L are considered to represent insufficiency. The majority of research findings concur that serum 25(OH)D should be higher than 50 nmol/L, but some recommend even higher serum levels (e.g. higher than 75 or even 250 nmol/L).
The general consensus across the latest peer-reviewed research literature acknowledges the inherent individual variation that exists regarding vitamin D status, and whilst supporting the notion that above the level of 150 nmol/L there are possible adverse effects, it is more common for people to experience such effects when above values of 400 nmol/L.
At Zinzino, we have considered the strength and quality of the evidence in this area, and our classification table is far more detailed as it has been directly informed by these findings and recommendations.
Vitamin D deficiency
Vitamin D is mostly associated with strong and healthy bones as it enables the absorption of calcium from food. Lack of vitamin D is traditionally associated with rickets, osteomalacia and osteoporosis.Many people have no symptoms, or their symptoms may be nonspecific and change over time.
Since the symptoms of vitamin D deficiency are often subtle and nonspecific, it’s important to get your blood levels tested if you suspect you may have a deficiency.
Common symptoms of vitamin D deficiency include:
- Increased susceptibility to colds or flu
- Changes in mood, including depression or anxiety
- Fatigue and tiredness
- Muscle weakness, or sore and painful muscles
- Bone pain
- Slow wound-healing
- Bone loss
- Hair loss
1,000,000,000 people
There is global concern about vitamin D deficiency, with one billion people, or 37% worldwide, estimated to be either vitamin D insufficient or deficient.Toxicity
Daily use of high-dose vitamin D supplements for several months is toxic and could lead to something called hypervitaminosis D or vitamin D toxicity.This is a rare but potentially serious condition, leading to your body absorbing too much of the calcium in food. The build-up of calcium in the blood (hypercalcemia) can cause nausea, vomiting, weakness, and frequent urination. Undiagnosed vitamin D toxicity could also progress to bone pain and kidney problems (such as the formation of calcium stones).