sweetkitty
We have differing responses to supplementation. by a factor of 6 to 1.
On average , a 75kg adult will raise their blood level of Vit D by 25 nmol/l for every 1000 IU of supplement daily ... long term. It takes two to three months to reach your equilibrium level with any particular daily dose.
You really should decide what blood level you need , and then keep it there , long term. Don't let it swing up and down by stopping and starting dosing. It is a really good idea to measure your level after you have been dosing for 3 months say , to check that you have the desired response. Some people don't. It may be because of absorption problems such as IBS, coeliacs, bile/gall bladder disorder, crohn's etc. IF you do find that you have absorption problems , you could switch to an oral spray , usually found as 1000 or 3000 or 4000 IU . per puff. This will go direct into the bloodstream, and bypass the digestive system.
Your blood level should reach over 100 , preferably 120 -140 . That is the human "normal"... throughout millions of years of evolution , and it still is , most people when exposed to plenty of sunlight , throughout the year will reach that level. Indeed , some will go as high as 200 . Here in the UK , we are unlikely to do that. Sunlight is weak as compared to where we evolved, ( Africa). Here in the UK , above 50 degrees North latitude , there is no UVB radiation in sunlight for 6 months of the year. ( Mid Oct to Mid April ) so mostly our blood levels drop dramatically. Also , by using suncreams , and avoiding vit D containing foods , we further compound the problem. Unfortunately vegan/ vegetarian food contains practically no Vit D. Some items may be fortified , but by tiny amounts.
Your intention to use 4000 to 5000 IU per day should give you a blood level in the region suggested. i.e above 120 , it does however presuppose that you don't have absorption problems.
As a vegan , you could well be low , because you don't consume much , but it really does make sense to check your level , with say a blood spot test after 3 months. Here is a possibility, an NHS lab. ( <a class="break-all" href="https://www.vitamindtest.org.uk/" rel="nofollow" target="_blank">www.vitamindtest.org.uk/</a> ). There are others .
The UK NHS will often say that a blood level of 50 is perfectly ok. It really isn't , it is too low, although many people do have those kind of levels.
When your blood level reaches around 100 or above , you body can absorb calcium at maximum efficiency. Vit D allows you to regulate your calcium absorption to your exact requirement. Higher Vit D , does NOT mean higher calcium blood levels, it means the correct calcium blood levels. Assuming you are consuming enough calcium to absorb. IF you don't consume enough calcium, then no matter what your vitamin D level, you won't be able to take up enough. So you should check your diet , to make sure you have enough calcium in it. In most normal circumstances , we do. That is why it is not normally necessary to supplement with calcium, IF your blood level of Vitamin D is over 100. But is does depend upon your circumstances, your diet etc. IF you consume over about 1000 mg of calcium you should be ok. You body requires about 200mg every day to replace that lost by natural processes. So , in that case , your regulatory system, Vit D / PTH hormone will adjust to absorb 20% of the calcium you ingest. In people with very low Vit D , the regulatory system may only be able to absorb say 15 % of the calcium ingested, thus resulting in the bones donating calcium to the blood , to keep blood levels of calcium where they should be. In order to do that the PTH hormone rises, in a kind of feedback loop. That is when problems with osteopenia, osteoporosis , osteomalacia could possibly arise.
It would be a good idea , to check your calcium level as well, after you have been supplementing for about 3 months, i.e when you vit D level is stable. IF when tested , your calcium is normal, then that part of your endocrine system is working correctly. . IF it is higher than normal, then you should see an endocrinologist. It is very very unlikely though.
Magnesium, is a co-factor of Vitamin D , and if you don't have enough in your diet , then you should change your diet to increase , or failing that you could supplement. Magnesium oxide , is not very absorbable, so you could try , mag citrate, glycinate, ororate. Dark greenstuff has plenty of magnesium, you probably have plenty , as a vegan ? Almonds also. A typical western diet does tend to be low in magnesium. Too much Mg supplement , all at once might lead to diarrhea, so build it up slowly , if you need it.
Well I hope that was helpful..!
Here is a thread , with lots of Vit D talk , advice etc. I did post there quite a bit, www.mumsnet.com/Talk/general_health/2421492-Vitimin-D-can-it-have-this-effect
I have posted quite a lot about vit D , here in Mumsnet , just search my nickname for more , or get back to me if you need any more information.
Best of luck
BTBH.
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