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Proteins are composed of various combinations of amino acids, and all dietary proteins are eventually converted into amino acids. The amino acids, which number about 22, are classified as either essential or nonessential. Essential amino acids are so-named because your body can't synthesize them and so it's essential that you get them in your diet.
The balance of essential amino acids in any particular protein determines its biological value. Since animal protein sources are higher in essential amino acids and more closely duplicate the amino acid pattern found in the human body, they're considered superior to plant-derived proteins, which often have either low or no amounts of essential aminos.
Recent research proves that from the perspective of muscle protein synthesis, essential aminos are extremely important. In fact, some studies show that getting as little as six grams a day of an essential amino acid mixture promotes muscle protein synthesis following resistance exercise, such as weight training. But watch out: Information on the importance of essential amino acids may lead you to conclude that the so-called nonessential amino acids are not very important.
That would be incorrect. Some nonessential amino acids have been reclassified as "conditionally" essential because under certain circumstances, such as high-stress conditions, the body cannot sufficiently synthesize them and their status changes from unessential to essential.
Examples of conditionally essential amino acids include glutamine and arginine. Normally, the body can synthesize them if you've taken in a sufficient supply of essential aminos. Sometimes, however, that synthesis can't take place rapidly enough glutamine and arginine are among the most popular amino acid supplements with athletes and bodybuilders today. Research on glutamine was originally derived from hospitalized patients, especially burn patients, who lose vast amounts of protein as a result of their injuries. Giving them glutamine reversed or halted the cascading catabolic effects on muscle that can result in death.
Thanks to the anticatabolic effect, glutamine earned a place in the supplement regimen of intensely training athletes. Later studies showed that it also appeared to prevent the immune-suppression effects of extended exercise-endurance events, for instance.
Arginine was initially promoted as a growth hormone releaser because doctors gave it intravenously to patients to treat growth hormone deficiency. Forms of arginine used for other purposes have also turned up in various food supplements, notably those that increase nitric oxide. Many of the food supplements that contain glutamine and/or arginine also contain another amino acid, taurine-particularly creatine supplements. That's because creatine is thought to encourage the cellular hydration that signals increased muscle protein synthesis. Glutarnine and taurine also appear to promote cellular hydration, which makes them synergistic with creatine.
If taurine did nothing more than promote cellular hydration, it would likely still be considered a useful supplement. But taurine-conditionally essential like glutamine and arginine-is far more essential to those engaged in exercise.
What Is Taurine?
Taurine was discovered in 1827 as a component of ox bile, which explains its name; Taurus is Latin for bull. Taurine is not incorporated into muscle and other tissues of the body like other amino acids but instead is found as a free, or unbound, amino acid or as part of short chains of aminos known as peptides. The significance of taurine wasn't recognized until studies in the 1970s found that it was an essential nutrient for cats. Without it, cats develop retinal degeneration leading to blindness and serious heart problems, which explains why cat food labels prominently display the taurine content.
Research on cats led some scientists to investigate whether taurine had any use for human nutrition. Initial studies found that babies fed on formula instead of mother's milk often developed taurine deficiency, since their bodies lacked the enzyrnes needed to synthesize it. Normally, taurine is synthesized from two other amino acids-the essential methionine and the nonessential cysteine-both of which contain sulfur.
In fact, some scientists suggest that taurine isn't a true amino acid, since it contains a sulfonic acid group; other aminos contain a carboxylic acid group. Taurine is found abundantly in the body, in brain, skeletal and heart muscle tissue. In muscle, it's the second most abundant free amino acid, behind glutamine. Taurine's presence in muscle suggests that it must be there for a reason.
The body can synthesize taurine from methionine and cysteine but not without the presence of the activated form of vitamin B6, or pyridoxine. So a lack of B6 in the diet can impair taurine synthesis. Controversy exists about just how well the body is able to make taurine. The main enzyme involved not that active in either humans cats. That's why some theories suggest that many people can benefit from taking supplemental taurine.
The most recognized function of taurine is its role in the production of bile salts. Bile, composed mainly of cholesterol, is a substance manufactured in the liver and stored in the gallbladder. In fact, the primary way the body rids itself of excess cholesterol is by shunting it into bile production. Bile itself promotes the digestion of fat by reducing its surface area, which makes it more digestible bylipases, or fat-digesting enzymes.
Even so, bile isn't soluble enough to work unless it's conjugated, or combined with other substances. When that happens, bile becomes bile salts, and the two main conjugating agents are the amino acids glycine and taurine. So taurine helps create bile salts and lower blood cholesterol, keeping it from floating through the bloodstream as low-density lipoprotein (the bad kind of cholesterol). High levels of LDL are a major risk factor for cardiovascular disease, especially oxidized LDL. The less LDL in the blood, the less chance of cardiovascular disease.
Taurine accelerates bile salt synthesis by boosting the genes responsible for making an enzyme called 7-alpha hydroxylase. The increased use of cholesterol for bile synthesis lowers blood levels of cholesterol, which in turn opens up LDL receptors on cells, also lowering cholesterol levels.
One study examined the effects of providing either three grams a day of taurine or a placebo to 30 overweight college students for seven weeks. Those in the taurine group had lower triglyceride levels in the blood, along with a reduced atherogenic index, a measure of the ratio of HDL cholesterol (the good kind) to triglycerides in the blood. Taurine increases HDL production by boosting the activity of the protein carrier of HDL, apolipoprotein.
The balance of essential amino acids in any particular protein determines its biological value. Since animal protein sources are higher in essential amino acids and more closely duplicate the amino acid pattern found in the human body, they're considered superior to plant-derived proteins, which often have either low or no amounts of essential aminos.
Recent research proves that from the perspective of muscle protein synthesis, essential aminos are extremely important. In fact, some studies show that getting as little as six grams a day of an essential amino acid mixture promotes muscle protein synthesis following resistance exercise, such as weight training. But watch out: Information on the importance of essential amino acids may lead you to conclude that the so-called nonessential amino acids are not very important.
That would be incorrect. Some nonessential amino acids have been reclassified as "conditionally" essential because under certain circumstances, such as high-stress conditions, the body cannot sufficiently synthesize them and their status changes from unessential to essential.
Examples of conditionally essential amino acids include glutamine and arginine. Normally, the body can synthesize them if you've taken in a sufficient supply of essential aminos. Sometimes, however, that synthesis can't take place rapidly enough glutamine and arginine are among the most popular amino acid supplements with athletes and bodybuilders today. Research on glutamine was originally derived from hospitalized patients, especially burn patients, who lose vast amounts of protein as a result of their injuries. Giving them glutamine reversed or halted the cascading catabolic effects on muscle that can result in death.
Thanks to the anticatabolic effect, glutamine earned a place in the supplement regimen of intensely training athletes. Later studies showed that it also appeared to prevent the immune-suppression effects of extended exercise-endurance events, for instance.
Arginine was initially promoted as a growth hormone releaser because doctors gave it intravenously to patients to treat growth hormone deficiency. Forms of arginine used for other purposes have also turned up in various food supplements, notably those that increase nitric oxide. Many of the food supplements that contain glutamine and/or arginine also contain another amino acid, taurine-particularly creatine supplements. That's because creatine is thought to encourage the cellular hydration that signals increased muscle protein synthesis. Glutarnine and taurine also appear to promote cellular hydration, which makes them synergistic with creatine.
If taurine did nothing more than promote cellular hydration, it would likely still be considered a useful supplement. But taurine-conditionally essential like glutamine and arginine-is far more essential to those engaged in exercise.
What Is Taurine?
Taurine was discovered in 1827 as a component of ox bile, which explains its name; Taurus is Latin for bull. Taurine is not incorporated into muscle and other tissues of the body like other amino acids but instead is found as a free, or unbound, amino acid or as part of short chains of aminos known as peptides. The significance of taurine wasn't recognized until studies in the 1970s found that it was an essential nutrient for cats. Without it, cats develop retinal degeneration leading to blindness and serious heart problems, which explains why cat food labels prominently display the taurine content.
Research on cats led some scientists to investigate whether taurine had any use for human nutrition. Initial studies found that babies fed on formula instead of mother's milk often developed taurine deficiency, since their bodies lacked the enzyrnes needed to synthesize it. Normally, taurine is synthesized from two other amino acids-the essential methionine and the nonessential cysteine-both of which contain sulfur.
In fact, some scientists suggest that taurine isn't a true amino acid, since it contains a sulfonic acid group; other aminos contain a carboxylic acid group. Taurine is found abundantly in the body, in brain, skeletal and heart muscle tissue. In muscle, it's the second most abundant free amino acid, behind glutamine. Taurine's presence in muscle suggests that it must be there for a reason.
The body can synthesize taurine from methionine and cysteine but not without the presence of the activated form of vitamin B6, or pyridoxine. So a lack of B6 in the diet can impair taurine synthesis. Controversy exists about just how well the body is able to make taurine. The main enzyme involved not that active in either humans cats. That's why some theories suggest that many people can benefit from taking supplemental taurine.
The most recognized function of taurine is its role in the production of bile salts. Bile, composed mainly of cholesterol, is a substance manufactured in the liver and stored in the gallbladder. In fact, the primary way the body rids itself of excess cholesterol is by shunting it into bile production. Bile itself promotes the digestion of fat by reducing its surface area, which makes it more digestible bylipases, or fat-digesting enzymes.
Even so, bile isn't soluble enough to work unless it's conjugated, or combined with other substances. When that happens, bile becomes bile salts, and the two main conjugating agents are the amino acids glycine and taurine. So taurine helps create bile salts and lower blood cholesterol, keeping it from floating through the bloodstream as low-density lipoprotein (the bad kind of cholesterol). High levels of LDL are a major risk factor for cardiovascular disease, especially oxidized LDL. The less LDL in the blood, the less chance of cardiovascular disease.
Taurine accelerates bile salt synthesis by boosting the genes responsible for making an enzyme called 7-alpha hydroxylase. The increased use of cholesterol for bile synthesis lowers blood levels of cholesterol, which in turn opens up LDL receptors on cells, also lowering cholesterol levels.
One study examined the effects of providing either three grams a day of taurine or a placebo to 30 overweight college students for seven weeks. Those in the taurine group had lower triglyceride levels in the blood, along with a reduced atherogenic index, a measure of the ratio of HDL cholesterol (the good kind) to triglycerides in the blood. Taurine increases HDL production by boosting the activity of the protein carrier of HDL, apolipoprotein.
