Micronutrient 'hyposynthesis'

[MWM]

I think it's correct to say it's widely documented that the use of testosterone causes hypogonadism, because the body decreases the synthesis of its own testosterone in response to the introduction of testosterone into the system from an external source. Is there any evidence to suggest that a similar phenomenon occurs in the case of any other chemicals which are commonly supplemented? I'm thinking in particular of vitamin D. In theory, could you mega-dose a vitamin D supplement to the extent that the body shuts down its own natural production?

[Robert Santana]

Not necessarily. You store some of it in the adipose tissue and if you mega dose enough you start to develop symptoms of toxicity.

[Yngvi]

I think it's correct to say it's widely documented that the use of testosterone causes hypogonadism, because the body decreases the synthesis of its own testosterone in response to the introduction of testosterone into the system from an external source. Is there any evidence to suggest that a similar phenomenon occurs in the case of any other chemicals which are commonly supplemented? I'm thinking in particular of vitamin D. In theory, could you mega-dose a vitamin D supplement to the extent that the body shuts down its own natural production?

I feel like there are a few 1,000 page biochemistry books I should point you to...

[Philbert]

I think it's correct to say it's widely documented that the use of testosterone causes hypogonadism, because the body decreases the synthesis of its own testosterone in response to the introduction of testosterone into the system from an external source. Is there any evidence to suggest that a similar phenomenon occurs in the case of any other chemicals which are commonly supplemented? I'm thinking in particular of vitamin D. In theory, could you mega-dose a vitamin D supplement to the extent that the body shuts down its own natural production?

Regarding vitamin D specifically: The supplements available over the counter are not the active hormone, they are precursors. The natural source of hormone precursor is a non-enzymatic (therefore not regulated) reaction occuring when cholesterol is exposed to UV light. The precursor is then processed by the liver and kidney (regulated in response to calcium and parathyroid hormone levels) to produce the active hormone. The active hormone is available by prescription in the United States, and is used for treating hypocalcemia due to hypoparathyroidism. If you inappropriately dosed active hormone for a long time you would be more likely to develop symptomatic hypercalcemia than suppression of vitamin D production. In the United States this would be unlikely unless you were buying drugs on the black market, or had chronic hypoparathyroidism and a significant change in calcium intake or excretion without dose adjustment.

[Robert Santana]

Regarding vitamin D specifically: The supplements available over the counter are not the active hormone, they are precursors. The natural source of hormone precursor is a non-enzymatic (therefore not regulated) reaction occuring when cholesterol is exposed to UV light. The precursor is then processed by the liver and kidney (regulated in response to calcium and parathyroid hormone levels) to produce the active hormone. The active hormone is available by prescription in the United States, and is used for treating hypocalcemia due to hypoparathyroidism. If you inappropriately dosed active hormone for a long time you would be more likely to develop symptomatic hypercalcemia than suppression of vitamin D production. In the United States this would be unlikely unless you were buying drugs on the black market, or had chronic hypoparathyroidism and a significant change in calcium intake or excretion without dose adjustment.

Calcitriol and its analogues are prescription drugs. There is absolutely no reason for a healthy person to take that.

[Yngvi]

Calcitriol and its analogues are prescription drugs. There is absolutely no reason for a healthy person to take that.

Agreed. The body has feedback loops that will prevent you from getting too much Vitamin D. It is not a good idea for a healthy person to bypass those feedback systems.

[MWM]

Thanks for the responses everyone. What's I'm taking away from this is that, aside from hormones, there aren't any substances synthesised in the body which can be supplemented to the extent of doing long-term damage do the body's own production. And of course there are other ways to do yourself damage with needless/reckless supplementation.

The only supplement I take is 1000IU of vitamin D daily, because whilst I'm fairly confident I have a well-balanced diet which should prevent any major deficiencies, I spend most of my days indoors and definitely get far less sunlight than nature intended. Without the supplement I see no reason to believe that I don't number among the apparent majority of people in the developed world who are deficient. I think this is sensible, but I welcome any other insight.

[Robert Santana]

1000 IU should be plenty. Get your levels checked in 3 months or so and see what happens.

[Yngvi]

What's I'm taking away from this is that, aside from hormones, there aren't any substances synthesised in the body which can be supplemented to the extent of doing long-term damage do the body's own production. And of course there are other ways to do yourself damage with needless/reckless supplementation.

Careful there.

[kcjason]

I think it's correct to say it's widely documented that the use of testosterone causes hypogonadism, because the body decreases the synthesis of its own testosterone in response to the introduction of testosterone into the system from an external source. Is there any evidence to suggest that a similar phenomenon occurs in the case of any other chemicals which are commonly supplemented? I'm thinking in particular of vitamin D. In theory, could you mega-dose a vitamin D supplement to the extent that the body shuts down its own natural production?

You say this is widely documented, but I didn't find any good source discussing this as a risk of TRT. I'm not disputing this, but could you link to a couple sources?