Problem:
Low carb dieters sometimes find that their cholesterol has gotten very high. This has been a conundrum for the low carb community. Its estimated that up to 30% can have this happen. It finally happened to me.
Hypothesis: A low carb diet can cause a gradual increase in rT3 over time. rT3 can interfere with T3 enough in the liver to cause high LDL-C. (The liver needs T3 to remove LDL from the blood.)
Background:
Last year I checked my lipids 5 times. Three times my cholesterol was very high but twice it was relatively normal.
In retrospect, the 3 times my cholesterol was high corresponded with times when my rT3 was likely raised:
- 1st time I took 40,000 iu of vit-D3 for a month.
- 2nd time I had a mild respiratory infection.
- 3rd time I experimentally took 30 mg/d of propranolol for a month (for essential tremor)
High Vit-D3, infection, and beta-blockers will all increase rT3 according to Dr Westin Childs.
When I checked my T3 / rT3 ratio it was 0.04 while Dr Childs says the minimum should be 2.0. In my case even minor variations in rT3 seem to have a large effect on my LDL-C. I have been on a low-insulinogenic & time-restricted eating diet for nearly 10 yrs. I also had a thyroidectomy due to childhood tonsil shrinking radiation and am on L-thyroxine (T4).
Is rT3 inert?
The medical community as a whole considers rT3 to be inert with no medical relevance and will refuse to test it.
Dr Weston Childs disagrees. He explains that rT3 is a natural response to infection or famine; and, it is raised by various forms of dieting including time-restricted eating and calorie restriction. Also, it is frequently high in patients on L-thyronine (T4) therapy.They only become symptom free after lowering rT3 by taking exogenous liothyronine (T3)..
A low carb diet causes a metabolic shift into glucose-sparing mode which [I hypothesize] In some people may trigger rT3.
rT3 seems to be blocked from entering most cells lending support to the conclusion that it is medically inert.
It appears that rT's evolved purpose is mainly to raise LDL-C in times of need.
It would be interesting to find out the T3 / rT3 ratio of those low-carb dieters with high cholesterol.
Edited by RWhigham, 18 March 2018 - 09:18 PM.