Vitamin D supplementation: What you need to know
Vitamin D supplementation has been labelled somewhat of a miracle supplement, helping to prevent anything from osteoporosis to autoimmune diseases, cancer, blood pressure regulation, immune health, cardiovascular disease, obesity and more.
It has become the most studied nutrient of recent decades and continues to have a lot of ongoing research. In recent years it has been noted that there is a receptor for vitamin D on almost every cell in the human body, which brings home the significance of vitamin D on overall health.
Why is vitamin D so important?
Vitamin D is a fat-soluble vitamin, synthesised by our skin when exposed to UVB radiation (sunlight). This is initially in a form that travels to the liver where it can be converted into a slightly more active form known as 25-hydroxyvitamin D. This is the form typically tested for, however, it is not the most metabolically active form.
A more active version it is eventually converted into is known as calcitriol or 1, 25 dihydroxyvitamin D. At this point it is no longer considered a vitamin, but instead a steroid hormone, much like estrogen, testosterone, progesterone, cortisol etc.
Many of vitamin D actions relate to mineral regulation, especially calcium. Vitamin D increases calcium absorption from the digestive tract. Interestingly if our body needs more calcium it can increase the active form of vitamin D, thus increasing absorption of calcium.
Of all the nutrients that are easily tested, vitamin D is the one that is most common, insufficiencies/deficiencies seen without supplementation. Research suggests around 40-50% of people are low in vitamin D. There has even been an increase in rickets, a vitamin D deficiency syndrome seen in children.
Why is it that so many people have vitamin D deficiency?
First or all, vitamin D is known as the sunshine vitamin. The majority of vitamin D that we have in our body is due to sunlight exposure and has very little to do with food intake. Whilst some foods like eggs, fish and dairy have the D3 form and others have the D2 form such as mushrooms or fortified foods, the levels of vitamin D are still very low, so relying on food alone for vitamin D is not realistic to prevent D insufficiency.
Thus, one area at which vitamin D might be low, is the lack of light exposure in modern day life. We tend to go from our homes, travel in our car to our places of work that are typically found indoors. We work through our lunch breaks and often find ourselves working long hours, thus rarely exposing ourselves to sunlight.
Another question that I think might be worth asking is, is your body suppressing vitamin D levels for a good reason? Is it creating a D deficient state in an attempt to regulate other minerals such as calcium? Unfortunately, this is a very broad question that does not align with the current approach to vitamin D assessment and prescription, which is very black and white. For example, if low take more, irrespective of the underlying cause or looking at other markers that might help determine if this is the case or not.
How do I know if I need to boost my vitamin D levels?
25-hydroxy vitamin D is a widely available test. It can be done with your GP, private testing, full blood draws and even finger prick tests these days that are fairly inexpensive.
Personally I would always recommend looking at vitamin D alongside other health markers to ensure you are not being too reductionist in your approach.
The reference ranges are something that will vary from lab to lab. In my experience and from my research, I have come across optimal values which seem to be around 100-125nmol/l, with deficiency levels typically being below 30nmol/l and insufficiency below 50nmol/l.
According to some sources we can naturally achieve our body’s vitamin D requirements with around 5-30mins of unprotected sun exposure of at least 30% of the skin between the hours of 10am-3pm at least 3 x per week. This will vary, however, based upon what latitude you live at and the time of year, your skin type and ethnic origin.
Supplementing with vitamin D
If you do decide to supplement with higher dosages of vitamin D, then I recommend ongoing analysis of your vitamin D and other basic blood chemistry markers related to calcium regulation, kidney function etc every 3-6months. I would also avoid the mega dosing of vitamin D. I would consider anything about 10,000iu per day or more of vitamin D on average as mega dosing. Supraphysiological dosages are seen more as 30-40,000iu of vitamin D supplementation daily.
Vitamin D and Calcium
One of the major concerns with excessive vitamin D supplementation is excessive blood level of calcium; three animal studies have shown increased arterial calcification with vitamin D supplementation. Whilst animal studies are not conclusive, it should at least make us consider the risks on supraphysiological dosing.
Another interesting theory could be that vitamin D levels are low because the body wants low vitamin as a result of high calcium in the blood. If the body is aware of high calcium levels, it could be suggested that the body will purposefully lower vitamin D to prevent calcium absorption.
Increased blood calcium can results from low magnesium, pH imbalance, liver dysfunction, protein deficiency and more.
Low calcium is rarely an issue; in fact there are so many foods that contain calcium, even if you are dairy free. Low calcium is very much an issue with absorption and it being deposited in the right places or excessive utilisation/overtraining. The only time I have seen it necessary to consider calcium supplementation is using very specific forms with individuals that have multiple fractures, or sometimes just within a multivitamin and mineral for additional support, especially with people that train hard (lots of requirement) or are dieting hard (less intake).
Vitamin D & Vitamin K
Vitamin D and Vitamin K are also linked, especially in their connection to calcium. Amongst other things vitamin K helps to deposit calcium into bone, without it we do not use calcium properly. As with high vitamin D, dosing could potentially cause arterial calcification, low vitamin K may also contribute to this as well.
I do not recommend any higher dose supplementation of vitamin D without at least having vitamin K2 present in that product as well.
Vitamin D & Magnesium
Magnesium is crucial for optimal vitamin D status. It has been shown to support the metabolism of vitamin D and the sensitivity of our tissues to vitamin D. Various studies have demonstrated this relationship between magnesium and vitamin D function.
Magnesium is another of the most common nutrient insufficiencies that I see when running bloods on people, not to mention low magnesium symptoms like cramping, poor sleep, constipation/slow bowels, involuntary muscle spasms, poor energy levels and more. In fact, magnesium is involved in over 300 processes in the body.
Magnesium also helps with calcium balance, and concerns have been raised over high vitamin D supplementation and it’s potential impact on reducing magnesium further, whilst also increasing physiological consequences of high calcium to magnesium ratio.
Studies have also demonstrated that vitamin D supplementation with magnesium was more effective at raising vitamin D levels than vitamin D alone. That particular study suggested that magnesium supplementation alone has the potential to increase one’s vitamin D levels, especially if low magnesium is the rate-limiting factor.
Vitamin D & Vitamin A
Vitamin A appears to be able to help prevent vitamin D toxicity and vice versa, thus also helping to prevent against excessive calcification.
The importance of balance
Nutrient status is typically as much about balance than anything else. When there is a low level of single nutrient it will serve you well to consider why that might be and when trying to correct an insufficiency, consider the interactions between associated nutrients.
Taking mega-dosages of single nutrient comes with risks, many of our nutrients work antagonistically or synergistically with one another, thus high dosing one might be depleting another or creating an excess elsewhere.
With all this in mind I was pleased to be able to formulate a well-balanced Vitamin D Complex for the forthcoming Fit For Films P-Form range.
Our vitamin D formula includes the following:
- Cholecalciferol (Vitamin D3) – 3000iu
- Retinyl Palmitate (Vitamin A) – 500iu
- Menaquinone-7 (Vitamin K2) – 50mcg
- Mixed tocopherols (d-alpha tocopherol, d-gamma, d-beta, d-delta(Vitamin E)) – 200iu
- Magnesium glycinate – 200mg
This provides a balance of fat-soluble vitamins, with a highly absorbable form of magnesium, to assist on the balance that I look for when supporting one’s nutrient status and optimising vitamin D status.
I have chosen dosages in our product that I am comfortable recommending to individuals without prior testing, and those with known low vitamin D are able to dose at a higher level with professional support.