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To supplement or not to supplement Vitamin D? That is the question.
Actually a hormone, Vitamin D is important for our joints, energy levels, immune system and also ties in to our thyroid hormones too. After all, a deficiency in Vitamin D can stop T3 from correcting your metabolic rate, leaving you with symptoms such as low energy, cold intolerance and weight gain.
Low Vitamin D Levels and Hypothyroidism
Symptoms of low or deficient Vitamin D include:
- Muscle and joint pain
- Muscle and joint weakness
- Bone ‘pain’
- Tiredness or fatigue
- Hair loss
Inadequate levels of Vitamin D can even stop your thyroid medication from working as well as it should do.
Many hypothyroidism patients have low or possibly even deficient Vitamin D levels and do not realise.
You should therefore ask you doctor to test for 25-hydroxy D if you think you could have low levels.
I didn’t suspect mine to be low but upon testing, it was below the bottom of the range, showing that I was deficient in this important hormone! Supplementing Vitamin D and getting my levels back to optimised levels helped my health a lot. My energy levels improved drastically. How many of us are still tired on thyroid medication but putting it down to the hypothyroidism and missing another possible cause?
The optimal level as reported by most sources for Vitamin D seems to be 80ng/ml or above, or as close to the top of the reference range as possible.
I keep mine towards the top of this range with maintenance supplementation, meaning that I personally take 4000iu of Vitamin D3 a day (with Vitamin K2), retesting levels every 6 months, confirming that they stay around 100ng/ml (optimal for me). If I lower this dose, my levels drop drastically.
For those of us with Hashimoto’s as the cause for our hypothyroidism, it is also worth noting that Vitamin D has been shown to lower thyroid antibodies. 
Should You Supplement Vitamin D?
You will need to supplement Vitamin D if you’re low in it, and if you’re found to be deficient, you should receive this on prescription from a doctor. Usually a very high dose such as 50,000iu is given until levels return to within range.
You can find a UK Vitamin D test option here, with a worldwide test option here. Doctors are often happy to check for this common deficiency, but not always. So ordering your own test can be a valuable resource.
It is also worth knowing that we should always take Vitamin D3 with Vitamin K2. This is because Vitamin D3 improves calcium absorption across the GI tract and Vitamin K2 is needed to transfer calcium into your bones and not your arteries. 
Vitamin K2 regulates calcium in the blood, so combining Vitamin K2 with Vitamin D3 is often recommended because of the synergy between the two vitamins. Research shows a slower progression of calcification in those taking both vitamin K2 and vitamin D compared to those taking vitamin D alone. 
These are two popular Vitamin D and Vitamin K supplements:
The NHS say to take no more than 25mcg a day , the US government say no more than 400iu a day, the Endocrine Society say 1,500–2,000iu a day and the Vitamin D Council say 5,000iu a day. So, it’s not completely clear!
It all depends on what you need. My functional medicine practitioner advised that I take 10,000ui until my levels came up (from 40ng/ml to 80+ng/ml) and then I reduced this to 4,000iu per day to maintain optimal levels and have done for years now. But it’s a good idea to regularly retest levels to check where they are.
You need to be cautious of taking too much, though, and The Vitamin D Council recommends taking no more than the upper limit of 10,000iu a day for adults. 
Signs of Too Much Vitamin D Include:
- Low appetite
- Excessive urination
- Weakness and nervousness.
You could make yourself feel worse by taking too much, so do test your levels before considering supplementing and then retest often while taking supplements.
When To Take Vitamin D
If you do decide to supplement, then you should aim to take your Vitamin D3 supplement with dinner, as it’s the usually the fattiest meal of the day, which helps with absorption.
Have you found that supplementing Vitamin D has helped?
You can click on the hyperlinks in the above post to learn more and see references to information given.