Written by Shane Foley Thursday, 23 April 2009 09:09
Acccording to Prof Marshall, his recent research confirms previous understanding that vitamin D isn’t a vitamin but a hormone (Vitamin D2 is the seco-steroid ergocalciferol and D3, cholecalciferol) produced by the body itself and that ‘extra’ consumption of it isn’t required for physical health.
He also says notions that increased vitamin D intake helps in serotonin production, linked to maintaining normal brain chemical function, are incorrect.
“What we’ve shown is that all forms of vitamin D from outside the body are counterproductive to the body’s own ability to regulate its own internal production.”
While not advocating avoidance of the sun or other natural sources of vitamin D, Prof Marshall cautions that over-exposure can interfere with correct interaction between vitamin D and the body’s vitamin D receptor, mutating the genetic expression of the vitamin. He believes that recent social trends have seen a constant rise in human over-exposure to the vitamin.
“Historically the amount of sunshine which people have typically been getting, certainly up until the mid twentieth century when we started to do silly things like sunbathing and wearing bikinis, up until that time people were sourcing enough vitamin D from everyday foods like fish, mushrooms and eggs.”
Prof Marshall also suggests over-exposure has been enhanced first of all by encouraging vitamin regimes to create a ‘healthier’ lifestyle and also the regular addition of increased amounts to everyday foods. At this point Professor Marshall says he believes “…our bodies’ hormonal control system is being overwhelmed by the amount of external vitamin D.”
His concern is that after decades of vitamin D over-consumption, humans have become more susceptible to chronic diseases as our bodies naturally attempt to suppress excess levels of vitamin D, creating a vulnerability in our immune systems.
“By most measures, rates of chronic diseases that ought to be reduced by such supplementation continue to escalate,” he says.
“The good news is that we now understand far more closely what causes chronic disease and can work to produce a therapy.”
Prof Marshall says that vitamin D’s link to chronic disease is clearly underscored by observation that countries like China, which have not seen the same cultural fixation with supplementation, do not indicate the same patterns of vulnerability.
While referring to over-supplementation as “history’s greatest mistake”, Prof Marshall believes that it could prompt a reassessment of food additive recommendations that would see fewer substances promoted before their effect on human health was better understood.
