Revista de Medicina Desportiva (English) July 2018 - Page 22

besides some reports of minimal gastrointestinal symptoms. 6 To date, only one case has been reported that associates the ingestion of whey and creatine e and cholestatic liver disease. However, there are no prior cases documented and the studies in this field have revealed liver protection associated with the consumption of whey. The chronic intake of creatine, associated with the continuous supplementation of whey four weeks before the onset of symptoms, together with the clinical improvement after abstinence from these supplements, were the main reasons to explain the probable rea- son to cause this clinical situation. 15 Casein Casein is the major component of milk proteins, corresponding to approximately 80% of its protein composition. As the whey, casein is a protein with high biological value and rich in minerals, like calcium and phosphorus. The casein exists in the milk in the form of micelle, which allows it to form a kind of gel or clot in the stomach. This characteristic guarantees its efficiency on the nutri- ent supply, since the clot allows a sustained and gradual release of the amino acids to the systemic circula- tion for several hours, which guar- antees better use by the body and greater nitrogenous retention. 16.17 a) Types of supplements • Casein micellar • Calcium caseinate • Isolated • Concentrated • Hydrolyzed. b) Functions Scientific studies showed that sup- plementation with casein enhances maintenance and the muscle mass formation. 18,19 In 2011, a clinical trial on supplementation with whey comparing with casein, on a 1 st divi- sion Brazilian football team, found an increase in muscle mass in the casein group, without changes in the group that ingested whey. 18 Due to its high content in branched-chain amino acids, casein is a strong ally for the repair and recovery of miofibrilares lesions resulting from 20 july 2018 www.revdesportiva.pt physical exercise. 11 Because it is a slow absorption protein, the casein holds a strong satiating power, with considerable thermogenic effect and lipid oxidation, characteristics that justify their inclusion on hypocaloric diets for weight loss. 19 The main benefit of casein intake is its ability to inhibit muscular catabolism, which is about 34%. 20 Although it contributes only moder- ately to muscular protein synthesis, due to its strong inhibitory power of catabolism, casein induces more muscle mass retention than whey, after seven hours. 11,20,21 So, feeding or supplementation with casein before bedtime reveals an excellent way to avoid protein degradation and oxidation of amino acids occurring during the night fast. 11,22 Accord- ing to a study with 16 young people, published in 2012 in Medicine Science In Sports & Exercise, supplementa- tion with 40gr of casein, 30 minutes before bedtime, proved to be effective in stimulating the muscular protein synthesis and improving the overall muscle balance during the night recovery of the physical exercise. 23,24 c) Clinical applications Clinical trials with the different components of casein have been carried out, revealing favorable results in the following clinical applications: • Increase or maintenance of mus- cle mass 18 • Prevention of sarcopenia • Systolic and diastolic blood pres- sure reduction in patients with hypertension 25,26 • Prevention and treatment of cog- nitive decline 26 • Prevention of demineralization and incidence of tooth caries 27 . d) Side effects There are no known side effects of supplementation with casein. However, due to its high content in β-casein, its consumption is not advised to individuals with milk intolerance. 28 BCAA The BCAA (Branched-chain amino acids) are made up of three essen- tial amino acids: leucine, valine and isoleucine. Leucine, in addition to providing substrate, is a key element in the initiation of protein synthe- sis. 6,12,14,22 The BCAA, as opposed to the other amino acids, have their metabolism in the tissues other than in the liver (muscles, brain, kidney, adipose tissue). They are indispensa- ble elements in the protein synthesis and degradation, depending on the context, they can be substrate for the neoglicogénese and ensure the maintenance of the body levels of glutamate-glutamine. The glutamine has several functions in the body, notably protein synthesis, mainte- nance of kidney acid-base balance, production of glutathione, removal of ammonia from tissues, etc. 29 The main functions of the BCAA are the recovery of micro muscu- lar lesions induced by the physical exercise and the prevention of mus- cular catabolism, reasons for which the consumption is advised before and after the workout periods. 30 In addition to these, there are numer- ous advantages of supplementation with BCAA, for example, at the level of central fatigue. The decrease on the levels of tryptophan transported to the brain after supplementa- tion with BCAA slows the feeling of fatigue during training, allowing the increase of the intensity and the performance. 31,32 The BCAA ingested as supplement are quickly absorbed by the body. Since they do not suffer a lengthy digestion process, they are imme- diately absorbed by the intestine, causing rapid rising of the circulat- ing insulin, which ensures an ana- bolic effect on the muscular protein synthesis. 33 a) Components • L-Leucine • L-Valine • L-Isoleucine b) Presentation • Capsules • Liquid • Powder c) Functions The BCAA have a wide range of actions in the body, highlighting the following: • Increase and maintenance of body muscle mass 33