Vitamin D and Hypothyroidism

To supplement or not to supplement? That is the question. 

I personally do supplement vitamin D, but this is because I was shown to be very low – almost deficient in it. I take a high strength vitamin D supplement to help this.

But should you supplement it?

One of the many downsides of being hypothyroid, is the inability to absorb certain vitamins and minerals (usually due to low stomach acid). Many hypothyroid patients have low or possibly even deficient vitamin D and don’t realise it. You should therefore ask you doctor to test for 25-hydroxy D if you think you could have low levels.

I would always suggest getting it tested anyway, as there’s no harm in checking. 

Symptoms of low or deficient vitamin D include:

  • Muscle and joint pain
  • Muscle and joint weakness.
  • Bone ‘pain’.
  • Tiredness or fatigue.
  • Depression.

Inadequate levels of vitamin D can stop your thyroid medication from working as well as it should do.

Richard Shames, MD says: Thyroid treatment isn’t optimal — and may not work — if you do not have adequate vitamin D for the crucial final metabolic step, which takes place at the site where thyroid hormone actually works. This happens inside the nucleus of the cell. Vitamin D needs to be present at sufficient levels in the cell in order for the thyroid hormone to actually affect that cell. That is why vitamin D is so crucial.

A deficiency  in vitamin D can stop T3 from correcting your metabolic rate and so leave you with low energy, cold intolerance and weight gain. Vitamin D has also been shown to lower antibodies –


So, should you supplement it?

Many sources such as Stop The Thyroid Madness, Hypothyroid Mom and Mary Shomon say yes, if you’re low. This can include if your levels are on the low side, but not ‘low enough’ for your doctor to treat it. This can still make you feel rubbish. You want your levels to be optimal, not just in range.

So, how much?

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.

Here is a really good chart to help you decide how much you should possibly be taking to raise low levels:

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
  • Nausea
  • Vomiting
  • Thirst
  • Excessive urination
  • Weakness and nervousness.

You could make yourself feel worse by taking too much, so do test your levels before considering supplementing, as described above with the test from your doctor.

If you do decide to supplement, then you should take your vitamin D supplement with dinner, as it’s the usually the fattiest meal of the day and helps absorption, apparently.

The optimal level as reported by most sources for Vitamin D seems to be 50-80 ng/ml or as close to the top of the range as possible. This is where most people tend to feel best.

D3 is the type of supplement you’re looking for as it is the type of vitamin D naturally produced by your body in response to sun exposure, while vitamin D2 is not. when-you-realise-that-all-your-health-conditions-are-actually-all-because-of-a-poorly-treated-underactive-thyroid-d07b6

Always take D3 with 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.  K2 regulates calcium in the blood, so combining vitamin K2 with vitamin D3 is highly 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.

Two really popular vitamin D and K supplements are by Solgar:

Solgar-Vitamin D3 25mcg (1000iu) 90 Tablets

Solgar Vitamin K2 (MK-7) – 50 vegicaps

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I run a Facebook group, called Thyroid Family: Hypothyroidism Advice & Support Group. This group is for underactive thyroid/hypothyroidism patients only, and not medical professionals or anyone else. If you have any questions on living with hypothyroidism, or want some support, help or advice, please join us. 

I also run a group for the spouses, partners and other halves of hypothyroid patients, called Hypothyroid Patients Other Halves – Support & Advice Group. This is for the other halves only and not patients. 



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