Basics of carnitine chemistry
In nature it can be found in two stereoisomers, respectively: D-carnitine [S - (+) -] and L-carnitine [R - (-) -].
Both are biologically active, but only L-carnitine occurs naturally in animal tissues. Conversely, d-carnitine is considered toxic, as it tends to inhibit the activity of the L- form.
At room temperature, pure carnitine is a low-toxic water-soluble zwitterion that comes in the form of a white powder.
Carnitine was first extracted from meat in 1905, a food from which the Latin name derives " carnis'.
(FA) long chain right into the mitochondria; here they are then used to generate calories thanks to β-oxidation.
It also participates in the removal of cellular metabolic products, from the inside out.
Given its very important cellular metabolic roles, carnitine is more concentrated in tissues such as skeletal muscle and heart muscle, which can obviously metabolize fatty acids.
Carnitine and fertility
The carnitine content in semen is directly related to the number of spermatozoa and their motility.
Carnitine and diseases
The use of carnitine has been studied in various cardio-metabolic conditions, but it is still in the preliminary research phase for its potential adjuvant in the treatment of heart disease, type 2 diabetes mellitus and others. At the moment no effect has emerged on the lipemia and the prevention of mortality associated with cardiovascular diseases.
A meta-analysis found that L-carnitine supplement could improve heart function in people with heart failure, but research is insufficient to determine possible efficacy in reducing risk or treatment.
A clinical research has analyzed the efficacy of the use of L-carnitine in improving the parameters altered by type 2 diabetes mellitus.
The use of carnitine has no effect on most of the parameters related to end-stage renal disease, but it allows to restore the right levels of the same.
carnitine occurs mainly in the liver and kidneys, starting from its precursor lysine (amino acid).
As a rule, in the case of full metabolic function, a 70 kilogram (kg) person produces 11-34 milligrams (mg) of carnitine per day (day), achieving a total body content of around 20 g - almost entirely localized in muscle cells skeletal.
Adults who consume omnivorous diets - containing red meat and other foods of animal origin - ingest about 60-180 mg / day of carnitine.
Vegans take around 10-12 mg / day of carnitine.
Most (54-86%) of the carnitine taken from the diet is absorbed in the small intestine, and then enters the blood.
Foods rich in carnitine
The carnitine present in food is in the L- form.
The richest nutritional sources are products of animal origin, especially beef and pork.
Red meats tend to have higher levels of L-carnitine than white meats.
"Strict" vegetarians get little carnitine from food sources, as it is obviously found mainly in foods of animal origin.
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Carnitine deficiency is usually classified into two types:
- Primary: genetic diseases of carnitine synthesis, which can appear even at the age of five;
- Secondary: which can occur as a consequence of some disorders, such as chronic renal failure (increased excretion) or a reduction in absorption (use of antibiotic drugs, malnutrition *, digestive problems **).
* for example from anorexia nervosa;
** for example from anatomo-functional alteration of the intestine.
Metabolic defect in the oxidation of fatty acids
Over 20 human genetic defects in the transport or oxidation of fatty acids have been identified.
In these situations, acyl-carnitine molecules tend to accumulate in the mitochondria and are then transferred first into the cytosol and then into the blood.
For diagnostic purposes, plasma acyl-carnitine levels can be measured in neonates by analyzing a small blood sample using tandem mass spectrometry.
In mammals, when β-oxidation is defective by a genetic mutation or by an actual carnitine deficiency, ω-oxidation becomes the most important pathway - occurring in the endoplasmic reticulum of liver and kidney cells.
, muscle weakness, chronic fatigue, altered blood fat levels and heart ailments.In the newborn, carnitine deficiency is manifested by: cardiomyopathy, weakness and hypoglycemia.
carnitine is particularly widespread in the population of sportsmen, fitness lovers and bodybuilders.
Products containing L-carnitine, acetyl-L-carnitine and propionyl-L-carnitine are available in both pills and powders.
The daily amount is generally between 0.5 and 1.0 g.
Carnitine is also drugs approved by the Food and Drug Administration for the treatment of primary and some secondary carnitine deficiency syndromes.
At the moment, however, there are no clinical trials of sufficient quality to support the usefulness of dietary supplementation with carnitine in order to: increase muscle carnitine levels, improve sports performance (by increasing oxygen consumption in aerobic activity or other functions metabolic), reduce the onset of cramps, speed up post-workout recovery, optimize β-oxidation of AF and weight loss.
On the other hand, it is scientifically proven, or there are good presuppositions, to hypothesize that the supplementation of carnitine can improve:
- The state of health of preterm infants;
- The state of health of those suffering from primary (genetic) deficiency;
- Total body carnitine levels in people with chronic kidney disease;
- The reduction of C-reactive protein (biomarker of systemic inflammation) in subjects with chronic kidney disease;
- The management of anemia (but by injection);
- Glucose tolerance and fasting blood sugar in type 2 diabetes mellitus;
- The number and motility of spermatozoa in subjects with oligospermia.
