Every cell and tissue in our body have vitamin D receptors. This should give us a pretty good indication of how important vitamin D is for human health and yet, despite the growing rates of vitamin D deficiency around the world, there is still no medical consensus on what a vitamin d deficiency is! So, instead of asking is 10,000 iu's of D3 safe, perhaps a more pertinent question would be: is it safe to have a vitamin D deficiency?
After all, a vitamin D deficiency has been correctly linked to a lowered immune system, arthritis and the never ending list of autoimmune disorders that are affecting humanity at an alarmingly increasing rate.
The current RDA (recommended daily allowance) for vitamin D is 600 iu's. Like virtually all the RDA's for essential nutrients, this has been based on how much you need to avoid a serious deficiency and disease. In the case of vitamin D3, this would be rickets. You can find literally thousands of studies and articles on PubMed regarding vitamin D and there is scant evidence that it can be toxic unless you're taking way more than 10,000 iu's a day.
However, it is very important to take the co-factors for D3 alongside it, namely: magnesium, zinc and especially vitamin K2. D3 helps the body absorb calcium, but, crucially, K2 drives calcium from the arteries to where it's needed: the bones. It prevents calcium build up in the arteries, tissues, joints, lungs and kidneys, and transports the calcium on the back of LDL cholesterol (the so called bad cholesterol) to your bones keeping them strong and healthy.
What is an iu (international unit)? 1iu equates to a quarter of a microgram, so you may think that 10,000 iu's sounds like a lot, but it really isn't. We also have to consider the many barriers to absorbing vitamin D that so many people have: skin colour, age, obesity, insulin resistance, stress, the seasons, liver toxicity, gallbladder removal (lack of bile), gut inflammation and on it goes.
T-helper cells work to maintain our immune systems and to ensure that our immune systems do not attack themselves: autoimmune disorders. Well, T-helper cells are TOTALLY RELIANT on vitamin D for normal function. Why is it, then, that we are constantly told by the MSM and the "orthodox" medical industry to stay out of the sun, to wear hats and cover ourselves in chemical sunscreen that our body absorbs. Despite this advice that has been given to us over many decades, skin cancer rates continue to increase! As do Big Pharma profits.
N.B. Please do not take vitamin D3 at the same time as vitamin K2! It is a well established scientific fact that fat soluble vitamins compete with each other for absorption. I suspect that many other supplement companies who sell both vitamins in the same capsule are aware of this, but continue to peddle the gimmick anyway. I take K2 in the morning after my first meal of the day and I take D3 an hour before bed as this increases the melatonin production in the brain that promotes quality sleep.
Paul