There are two types of amino acid – the essential amino acid and the non-essential amino acid. The eight essential amino acids are isoleucine, lysine, leucine, methionine, phenylalanine, valine, threonine and tryptophan. These acids are also known as indispensable amino acid not because they are considered to be more important than the other amino acids but because they are not produced by the body. As they are not synthesized by the body these amino acids must be included in the diet. Non-essential amino acids are those acids that can be produced by the body on its own thus, it is not really necessary for this type of acid to be included in the diet.
Tryptophan is one of the essential amino acids. This essential amino acid have two main functions – that of preventing niacin deficiency and that of increasing the level of serotonin. Of all the amino acids, tryptophan is known to be the least abundant in any given diet. Although scarce, tryptophan is very necessary as it is converted by the liver into vitamin B3 (niacin and niacinamide). This helps prevent the symptoms of niacin deficiency.
Tryptophan has a major role in the production of neurotransmitters. Tryptophan acts as serotonin’s precursor. This nervous system messengers are responsible for regulating sleep patterns, appetite as well as the frame of mind of a person. Although the brain’s share for the ingested tryptophan is less that 1% getting it to pass through the blood brain barrier is a difficult task for the brain. The blood brain barrier protects the brain by preventing the entrance of toxins as well as the excessive levels of nutrients that may disrupt the regular brain functions. Serotonin can not pass through the blood brain barrier, tryptophan can. Unfortunately, tryptophan has to share the transport molecules with five other amino acids.
Tryptophan food sources include red meat, turkey, tuna, shellfish, soy beans and various soy products, dairy products, bananas, and nuts. Non-consumption of these foods would cause tryptophan deficiency. Dietary deficiency of this essential amino acid would have symptoms similar to protein deficiency. This includes impaired growth and weight loss. Tryptophan deficiency if coupled with niacin deficiency could result to pellagra, a disease that is typically characterized by dermatitis, dementia, diarrhea and even death. A low level of serotonin is another manifestation of tryptophan deficiency. Symptoms would include depression, irritability, impatience, anxiety, impulsiveness, inability to concentrate, impaired growth in children, unexplained weight loss or weight gain, carbohydrate cravings and overeating. People with tryptophan deficiencies would have trouble sleeping and when they do sleep they are unable to recall their dreams.
Deficiency in tryptophan can be due to dietary, health and lifestyle factors. Smoking, alcohol abuse, health concerns like diabetes and hypoglycemia, high sugar intake as well as too much consumption of protein can decrease the level of tryptophan conversion to serotonin. Vitamin B6 deficiency lowers serotonin level thus tryptophan conversion to niacin is impaired. Instead of providing more tryptophan a high protein diet would worsen the deficiency. As mentioned before, tryptophan competes with five other amino acids on its way to the brain. A high protein diet would cause these other five amino acids to be more active and stronger. The trick is to increase the supply of tryptophan to the brain is to ingest a diet high on carbohydrates. To counteract the effect of carbohydrates to the blood sugar, large amounts of insulin hormone is secreted by the body. This hormone clears other amino acids from the blood therefore more tryptophan will reach the brain.
People who are depressed, stressed and encountering problems would consume large amount of cakes, ice creams, chocolates, pizzas and many other comfort foods. By unknowingly increasing serotonin in the brain these people will be able to deal with the depression and anxiety.