Monday, March 23, 2009


Meat eating is a way of life amongst majority of the population across the world and forms an inseparable part of their diet. High quality proteins, essential vitamins and minerals that are critical for human growth are present in meat in abundance, making it one of the most concentrated form of foods known to man. The choice between white and red meats is often influenced by the presence of cholesterol in the latter and some time fish is suggested as an alternative to red meat. Added to this dilemma is the linkage between meat raising and greenhouse gas emission as livestock animals are the most polluting sources as far as environmental degradation is concerned accounting for more than 18% of emissions responsible for global warming. Further damage to the credentials of red meat is caused by the drastic changes taking place in farming of animals from a free roaming open farms of yesterday to the present day livestock pen system which seems to have changed the nutritional and health protecting qualities of meat very significantly.

There is a strong argument that man was not designed to eat meat like carnivorous animals and the structure of hands and profile of the teeth in human beings are being cited in support of such claims. Presence of alpha amylase enzyme in the saliva of humans is unique and this probably reflects the predominance of starchy foods in their diets during evolution. Supporters of meat eating tradition highlight the unique presence of Carnitine in the red meat to promote its consumption in moderate amounts. Carnitine is a quaternary ammonium compound synthesised in the liver and kidneys, the precursors being the amino acids Lysine and Methionine and its main role is to transport fatty acids from the cytosol to the mitochondria during break down of lipids. Presence of Ascorbic Acid (Vitamin C) is critical for this transformation. During growth and periods of pregnancy Carnitine need may exceed the normal supply through in vivo synthesis. Long chain acyl groups from fatty acids are conveyed to the mitochondrial matrix for breaking down through beta oxidation to acetates to obtain usable energy via the Tri Carboxylic Cycle (TCA).

During aging process fatty acid metabolism in various tissues is slowed down due to diminishing levels of Carnitine synthesised in situ adversely affecting the bones which require continuous reconstruction and metabolic functions of Osteoblasts and maintain bone mass. Reduction of Osteocalcin in blood plasma is indicative of reduced Osteoblast leading to on-set of Osteoporosis, especially amongst eldrerly people and post-menopause women. Carnitine is also being promoted as an antioxidant in lipid peroxidation of phospholipid membranes against oxidative stress induced at the myocardial and endothelial cells. Weight loss claims for Carnitine have not been substantiated so far, though the critical role of this chemical in burning of fat is well recognized. However it is widely believed that Acetyl- L- Carnitine exercises some effect on more efficient crossing of the blood-brain barrier, better energy metabolism, improved neurotransmitter function in brain and reduced fatigue in patients undergoing chemotherapy. Up to 2 g of intake per day is considered adequate if supplementation is called for in some cases as absorption saturation is reached at this level. Beyond that Carnitine can cause nausea, vomiting, stomach cramps and diarrhea.

Does Carnitine deficiency occur in humans? Difficult to make a positive statement because of the difficulties in monitoring Carnitine level in the body. 98% of Carnitine is confined to muscles, balance 2% being in the blood. In routine tests the ratio between Acyl-Carnitine to Free Carnitine in blood is determined and a ratio greater than 0.4 reflects deficiency, requiring supplementation. It is known that high fat diet, certain medications and low protein intake can manifest in Carnitine deficiency in the body and the symptoms may include chest pain, frequent tiredness, muscle weakness and pain, increased body fat and elevated cholesterol levels.

Highest levels of Carnitine is found to be in red meat like beef which provides about 95 mg per one serving of 3.5 ounces. Other sources include dairy products like milk and cheese, the concentration being 2-4 mg per serving. Tempeh is reported to contain about 20 mg of Carnitine. Carnitine can be biosynthesized using E.coli or Proteus sp which can convert protonobetaine or D-Carnitine to L-Carnitine. Butyrobetaine and 3-Dehydrocarnitine also are good precursors. While omnivorous humans get about 20-200 mg per day through the diet, intake for vegetarians and vegans is limited to 1 mg a day. It seems 75% of the requirement has to come from the diet while 25% is synthesized in the body. Since the half life of Carnitine in humans is 17 hours, over consumption may not pose any significant risk. These findings raise a pertinent question regarding any justification for external supplementation for normal healthy persons. Crass commercialism should not lead consumers astray by unsubstantiated claims and scarce scientific data to back them up.


No comments: