Why do I have to leave a gap between thyroxine and food?
I have, over the last 7 months,, been told by my consultant after going hyperthyroid last April, to leave an hour plus, but seem to go hyper/hypo and lack energy and can’t seem to get the dose right at present. Maybe it is so intricate and that is why it is taking time?
Thank you.
We need to leave that gap to enable the levothyroxine to be efficiently absorbed by the gut. It is all about the absorption of the hormones.
Thyroxine is just not well absorbed if you take it with food or anything in your stomach already. It works much better when taken alone.
A lot of people find it easier to take it at bed time, so plenty of time to absorb with no disruption. 🙂
levo is 'dissolved' in the stomach (it needs gastric acid to 'dissolve' ) ... i know it appears to dissolve in the mouth , but that is "all the other stuff that makes the tablet" .. the actual T4 is microscopic molecules .
"Levothyroxine, the levo-isomer of thyroxine, is insoluble in water and in other usual organic solvents (11)" ncbi.nlm.nih.gov/pmc/articl... (Levothyroxine Therapy in Gastric Malabsorptive Disorders)
Then once 'dissolved' , it is absorbed into the blood via the small intestine.
"Absorption and Bioavailability
Levothyroxine is mainly absorbed in the small intestine, more specifically through the duodenum, jejunum and ileum.10,11 Very little is absorbed in the stomach. Consequently, patients with shorter small intestines (bowel resection) have reduced absorption and require higher levothyroxine doses...
The normal acid environment in the stomach is necessary for L-T4 absorption....The absorption of levothyroxine appears to be influenced by gastric pH.17,18 Centanni et al. demonstrated that in euthyroid patients suffering from nontoxic multinodular goiter, impaired gastric acid secretion or the use of omeprazole was associated with increased dosing requirements in order to adequately suppress TSH" ncbi.nlm.nih.gov/pmc/articl... (A Review of the Pharmacokinetics of Levothyroxine for the Treatment of Hypothyroidism)
UNDER IDDEAL CONDITIONS.. (ie empty stomach / no other food in there to lower acid or mess with idea conditions in their small intestine ) most people will absorb about 80% of the T4 they swallow .
But ,, IF CONDITIONS ARE NOT IDEAL.. (ie they just ate dinner), THEY WILL ABSORB LESS than 80% .. for the sake of argument lets say "roast beef and mashed potatoes " means they only absorb 60% .
if they have a strong coffee before or after they take the tablet ,, their gut processes will be moving faster .. giving less time in the small intestine for the T4 to be fully absorbed before it gets excreted.
IF CONDITIONS ARE NOT CONSISTENT (ie we eat different thing, on different days, at different gap from out tablets) .. then every day we will absorb a different % of the T4 dose we take .. some days we'll get 80% , some days we'll only get 40%.
obviously this means our 'actual' dose (as opposed the what we think we are taking) is going up and down, all over the place ..
Great explanation, thanks.
I have always wondered why we are 'prisoners of drugs' rather than the other way round. ie.if we want to take thyroxine alongside food, then why can't we take a higher dose if food affects absorption.Why do we have to observe such strict rules when we could just up our dose, knowing not all will be absorbed.
We can do this ,,and some of us do..i always have a cup of tea with my levo , jimh111 always has porridge . BUT the key word there is "always" .
If i 'randomly' had tea , and jim randomly had porridge , we would both find it more difficult to know what our effective dose actually was, it would lead to periods of higher / lower dose dependant on eating/ drinking 'x with our tablets ... leading to varying effect on symptom control , and not obviously related to the day we did or didn't do 'x'.
The thing with 'rules' is , when you need to get an important concept about a complicated process across to thousands of people with varying degrees of interest / ability to understand the complexities , the only effective way to do it is to initially state a very simple 'rule', very clearly.
Once an individual has enough interest to understand the reasons, and functionality of the process in question , and the consequences on that process of doing (x/y/ z) instead of following the 'rule , then they can think for themselves about what they actually do on any particular occasion , and not stick to the 'rule'. But this only applies once they understand the nuts and bolts of the process, and 'why' the rule was made .
eg . i used to live somewhere with composting toilets .. they only compost properly if the proportions of poo/ urine / sawdust are managed correctly . If you get 30 visitors weeing in it for a week, you don't get compost .. you get a problem .
So we put a clear, simple sign up with a firm 'rule' on it , "don't NOT wee here, wee over there", "put ONLY one handful of sawdust in ".
Did the 10 of us who lived there 'always' follow the rule about 'never' weeing in the compost loo ? ,, no we did not,..... but that was because we knew how the composting process worked , we knew how to compensate and keep things in balance ,(and because it would be us that had to dig it out if it went wrong )
'rules' are a necessary and effective way to manage something important BEFORE people have shown enough interest to understood the complexities for themselves.
fifty one There are no hard rules. Folks can do what suits their lifestyle. I have several friends on levo who take it with breakfast or who are more haphazard in their taking of the tablets and they are well and happy. Folks on here however are mainly here because they still have symptoms. Many of us here need to maximise the benefits of our doses which is why we seem to be strict/pedantic/banging on about timing and absorption.
We provide information from our experience and knowledge. What folks then choose to do is up to them.
Thank you for your detailed response. I have gastric problems with reflux and indigestion and the doctor prescribed omeprazole but I am wary of taking it. Would the problem be affecting the absorption and would a long gap be required between thyroxine and the drug if I commence it? These symptoms have developed since covid last year.
Also, could you explain what eating different things means on different days? Are you referring to certain foods affecting absorption? If the hour gap is left, does it prevent malabsorption happening?
Low stomach acid is common hypothyroid symptom and suggests you might not be on adequate dose levothyroxine
Omeprazole will lower stomach acid further and lower vitamins
when were vitamin D, folate, ferritin and B12 levels last tested
What vitamin supplements are you currently taking
Thousands of posts on here about low stomach acid
healthunlocked.com/search/p...
But never assume you have low stomach acid
healthygut.com/4-common-bet...
Web links re low stomach acid and reflux and hypothyroidism
nutritionjersey.com/high-or...
stopthethyroidmadness.com/s...
thyroidpharmacist.com/artic...
How to test your stomach acid levels
healthygut.com/articles/3-t...
meraki-nutrition.co.uk/indi...
huffingtonpost.co.uk/laura-...
lispine.com/blog/10-telling...
Ppi
Omeprazole will lower vitamin levels even further
gov.uk/drug-safety-update/p...
webmd.com/heartburn-gerd/ne...
pharmacytimes.com/publicati...
PPI and increased risk T2 diabetes
gut.bmj.com/content/early/2...
Iron Deficiency and PPI
medpagetoday.com/resource-c...
futurity.org/anemia-proton-...
as far as i understand it (which is NOT fully), taking omeprazole lowers the stomach acid /puts a coating on the stomach , this effect is quite long lasting over the day (i think) , so for omeprazole use it doesn't much matter how long before or after the levo you take it , because the the effect of the omeprazole is (supposed to be) lasting all day anyway. Basically if someone is using omeprazole at all ,then the amount of Levo they absorb from the tablet will (usually) be less, tha if they weren't. So they take omeprazole consistently and 'x' dose of Levo and (if their Doctor is on the ball) their Levo dose will be adjusted over time to compensate , based on their blood results.
Regarding eating different things on different days , we know a few substances definitely affect absorption of Levo , eg calcium , iron . caffeine , because they have been tested in research studies. Most food substances have not been tested , but it is reasonable to assume 'most things' will have 'some effect' ,, that effect might be insignificant, or it might be considerable , we just don't know.
So we just have to be as consistent as possible, and even though we eat different stuff each day if we always leave at least an hour after levo , we are doing the best we can to minimise whatever that effect of that food might be .
Some things do need longer than an hour, see slowdragon / seasidesusies detailed replies on the forum for more detail on which vitamin supplements/ drugs need longer gaps . i'm not sure enough of my facts to say here, but some need 4 hrs .
I'm still not convinced of the details of that explanation. (The overall story is fine!)
Yes - acidity in the stomach might have a role. But levothyroxine is insoluble in water and acidified solutions. (My added words.)
Levothyroxine is more soluble in alkaline solutions. Which occur in the intestines due to secretion of bicarbonate. And it is there that levothyroxine is primarily absorbed. I keep coming back to the same question. Does lower stomach acid also result in reduced secretion of bicarbonate?
will have to think about that and digest it fully , while i digest my toast and marmalade 
that is really very interesting what you say. thank you
Your dose levothyroxine should not be adjusted by TSH
ESSENTIAL To test full thyroid and vitamin levels
If Ft3 is not over range you’re not over medicated
ALWAYS test thyroid levels early morning and last dose levothyroxine 24 hours before test
Do you always get same brand levothyroxine at each prescription
When were vitamin levels last tested.
What vitamin supplements are you currently taking
Do you have autoimmune thyroid disease also called Hashimoto’s usually diagnosed by high thyroid antibodies
List of private testing options and money off codes
thyroiduk.org/getting-a-dia...
Medichecks Thyroid plus antibodies and vitamins
medichecks.com/products/adv...
Blue Horizon Thyroid Premium Gold includes antibodies, cortisol and vitamins
bluehorizonbloodtests.co.uk...
If you can get GP to test vitamins then cheapest option for just TSH, FT4 and FT3
£29 (via NHS private service ) and 10% off down to £26.10 if go on thyroid uk for code
thyroiduk.org/getting-a-dia...
Monitor My Health also now offer thyroid and vitamin testing, plus cholesterol and HBA1C for £65
(Doesn’t include thyroid antibodies)
monitormyhealth.org.uk/full...
10% off code here
thyroiduk.org/getting-a-dia...
Only do private testing early Monday or Tuesday morning.
Watch out for postal strikes, probably want to pay for guaranteed 24 hours delivery
Looking at previous posts
You had RAI
Last test results you look under medicated and poor conversion of Ft4 to Ft3
Many people after RAI need the addition of small doses of T3 prescribed alongside levothyroxine
Suggest you get full thyroid and vitamin testing done see exactly what’s going on before considering seeing thyroid specialist endocrinologist for T3
Email Thyroid U.K. for list of thyroid specialist endocrinologists and doctors who will prescribe T3 if clinically appropriate
tukadmin@thyroiduk.org
Thyroxine 
Thyroxine
Thyroxine 
Anxiety on thyroxine 
