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Anyone speculate oral vs inj dosages? If we never get 1000 mg/mL carnitine for injection, how much oral and what form to compensate.
Say 500 mg per day injection; how much oral carnitine to be the equivalent of 1000 mg/d inj? And what forms of carnitine?
I don't care about TMAO.
My understanding based on research I have done is that bioavailability of oral l-carnitine is low and ranges between 5-18%, because of this the recommended dose is 1-6 grams
Dietary l-carnitine is much higher but still varies widely between individuals based on many factors including previous diet
Obviously injectable l-carnitine is closer to 100% bioavailability and the recommended dose is 500 mg- 1 gram.
The oral bioavailability could vary so greatly that one cant put a number on it. Previous red meat consumption vs vegan diet, how l-carnitine is synthesized in the liver and many other factors that are unique to the individual will determine bioavailability. Because of this you can’t put a hard and fast number on oral vs injectable bioavailability. One person may need 1 gram oral and the next person may need 6 grams oral for an equivalent of the injectable form.
Here’s a quote about the elimination and reabsorption of oral supplementation -
“
Renal reabsorption of free L-carnitine is normally very efficient; in fact, an estimated 95% is thought to be reabsorbed by the kidneys
(1). Therefore, carnitine excretion by the kidney is usually very low. However, several conditions can decrease the efficiency of carnitine reabsorption and, correspondingly, increase carnitine excretion. Such conditions include high-fat, low-carbohydrate diets; high-protein diets; pregnancy; and certain disease states (see
Primary systemic carnitine deficiency)
(12). In addition, when circulating L-carnitine concentration increases, as in the case of oral
supplementation, renal reabsorption of L-carnitine may become saturated, resulting in increased urinary excretion of L-carnitine“
Source-
Oregon State edu