Protein Shakes, Meal Replacement Products, Thermogenic products,

Bodybuilding supplements are substances taken by athletes involved in weight training or other sports to aid in the building of lean muscle mass or to cause fat loss.

Bodybuilding supplements may also be used to improve sports performance and improve recovery from events and training. One important distinction exists in many weight training groups between supplements and anabolic steroids. There is a common misconception among non-supplement-users that supplementation for muscle-building purposes is the same as steroid use or, at the very least, leads to steroid use.However, this charge is often challenged by supplement users on the grounds that supplements do not mean to change natural hormone levels (primarily those of testosterone) beyond natural limits, while anabolic steroids do.

Bodybuilders often take a powdered form of protein, the essential building blocks for muscle. Protein powder is generally consumed immediately before and after exercising, or in place of a meal. Having sufficient protein intake allows for efficient growth and repair of muscle tissue.

Whey protein is the most commonly used type of protein. It contains high levels of all the essential amino acids not produced by the human body, and is absorbed by the body very quickly.
Casein protein (or Milk protein) is the richest in glutamine, an amino acid that aids in recovery, and has casomorphin which helps the body to absorb the amino acids over a long time.
Soy protein contains all essential amino acids, and is an alternative protein for vegetarians. Soybeans also contain isoflavones, a type of phytoestrogen, which have a weak estrogenic activity.
Egg white protein is a lactose- and dairy-free protein.
Hemp seed contains complete and highly-digestible protein and hemp oil is high in essential fatty acids.

Glutamine
Glutamine is the most abundant amino acid found in human muscle and is supplemented because supplement manufacturers claim the body's natural glutamine levels are depleted during anaerobic exercise. It is argued that bodybuilders should supplement with glutamine, as deficiency may lead to a weakened immune system and wasting of muscle tissue. It is sold as a micronized, instantly soluble powder. Some studies have shown there to be no significant effect of glutamine on bench press strength, knee-extension torque or lean muscle mass when compared to controls taking a placebo, though another study found that glutamine is beneficial in raising T-helper/suppressor cell ratio in long distance runners.


Branched chain amino acids
Amino acids are the building blocks of protein; the body breaks consumed protein into amino acids in the stomach and intestines. There are three branched chain amino acids (BCAAs): leucine, isoleucine, and valine. Each has numerous benefits on various biological processes in the body. Unlike other amino acids, BCAAs are metabolised in the muscle and have an anabolic/anti-catabolic effect on it.


Meal Replacement Products (MRPs) are either pre-packaged powdered drink mixes or edible bars. Both are consumed in the place of a whole-food meal. Generally MRPs are high in protein, low in fat, have a low to moderate amount of carbohydrates, and contain a wide array of vitamins and minerals.

The majority of MRPs use whey protein, calcium caseinate or micellar casein, soy protein, and egg albumin as the protein source. Carbohydrates are typically derived from maltodextrin, oat fiber, brown rice, or wheat flour. Some also contain flax oil powder as a source of essential fatty acids.

MRPs can also contain other ingredients that are deemed beneficial to bodybuilders. These can include, but are not limited to: creatine monohydrate, glutamine peptides, L-glutamine, calcium alpha-ketoglutarate, additional amino acids, lactoferrin, conjugated linoleic acid, and medium chain triglycerides.


Prohormones
Main article: Prohormone
Prohormones are precursors to hormones and were most typically sold to bodybuilders as a precursor to the natural hormone testosterone. This conversion requires naturally occurring enzymes in the body. Side effects are not uncommon, as prohormones can also convert further into DHT and estrogen. To deal with this, many supplements also have aromatase inhibitors and DHT blockers such as chrysin and 4-androstene-3,6,17-trione. To date most prohormone products have not been thoroughly studied, and the health effects of prolonged use are unknown. Although initially available over the counter, in 2004 their purchase was made illegal without a prescription in the US, as it remains so in almost all countries and is proscribed by most sporting bodies.


Creatine
Main article: Creatine supplements
Creatine is an organic acid naturally occurring in the body that supplies energy to muscle cells for short bursts of energy (such as lifting weights) via creatine phosphate replenishment of ATP. A number of scientific studies have shown that creatine can increase strength, energy, muscle mass, reducing recovery time. In addition, recent studies have also shown that creatine improves brain function and reduces mental fatigue.

It increases what is known as cell volumization by drawing water into muscle cells, making them larger. This intracellular retention should not be confused with the common myth that creatine causes bloating (or intercellular water retention). Creatine is sold in a variety of forms, including creatine monohydrate, and creatine ethyl ester, amongst others. Though all types of creatine are sold for the same purposes, there are subtle differences between them, such as price, and necessary dosage. Non-supplemental suppliers of creatine include various types of offal, red meat, and kidney meat.

Claims that creatine could be stressful to the kidneys (due to primary renal elimination via creatinine) have been proven false through studies conducted by universities and independent organizations.


A thermogenic is a broad term for any supplement that the manufacturer claims will cause thermogenesis, resulting in an increased metabolic rate, increased body temperature and consequently an increased rate in the burning of body fat. Until recently almost every product found in this supplement category comprised the "ECA stack": ephedrine, caffeine and aspirin. However, on February 6, 2004 the Food and Drug Administration (FDA) banned the sale of ephedra and its alkaloid, ephedrine, for use in weight loss formulas. Several manufacturers replaced the ephedra component of the "ECA" stack with bitter orange or citrus aurantium (containing synephrine) instead of the ephedrine. To date the effectiveness of this new combination is not conclusive.


Testosterone boosters
There are several naturally occurring plants and vitamins as well as synthetic chemicals that supplement companies claim may produce an increase in testosterone levels. However, the validity of many of these products is questionable due to a lack of valid scientific research showing their effectiveness at this time. Some commonly taken supplements of this type are ZMA and Tribulus terrestris.

The relatively new drug 4-androstene-3,6,17-trione may increase the testosterone-estrogen ratio.

Excess testosterone can cause undesirable side effects, such as hair loss and acne, and may be converted into estrogens, which can have undesirable effects on males, such as gynecomastia and testicular atrophy.

Proteins are organic compounds, made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxy

Proteins are organic compounds made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid residues. The sequence of amino acids in a protein is defined by the sequence of a gene, which is encoded in the genetic code. In general, the genetic code specifies 20 standard amino acids, however in certain organisms the genetic code can include selenocysteine - and in certain archaea - pyrrolysine. The residues in a protein are often observed to be chemically modified by post-translational modification, which can happen either before the protein is used in the cell, or as part of control mechanisms. Proteins can also work together to achieve a particular function, and they often associate to form stable complexes.

Like other biological macromolecules such as polysaccharides and nucleic acids, proteins are essential parts of organisms and participate in every process within cells. Many proteins are enzymes that catalyze biochemical reactions and are vital to metabolism. Proteins also have structural or mechanical functions, such as actin and myosin in muscle and the proteins in the cytoskeleton, which form a system of scaffolding that maintains cell shape. Other proteins are important in cell signaling, immune responses, cell adhesion, and the cell cycle. Proteins are also necessary in animals' diets, since animals cannot synthesize all the amino acids they need and must obtain essential amino acids from food. Through the process of digestion, animals break down ingested protein into free amino acids that are then used in metabolism.

The word protein comes from the Greek word πρώτειος (proteios) "primary". Proteins were first described and named by the Swedish chemist Jöns Jakob Berzelius in 1838. However, the central role of proteins in living organisms was not fully appreciated until 1926, when James B. Sumner showed that the enzyme urease was a protein. The first protein to be sequenced was insulin, by Frederick Sanger, who won the Nobel Prize for this achievement in 1958. The first protein structures to be solved were hemoglobin and myoglobin, by Max Perutz and Sir John Cowdery Kendrew, respectively, in 1958. The three-dimensional structures of both proteins were first determined by x-ray diffraction analysis; Perutz and Kendrew shared the 1962 Nobel Prize in Chemistry for these discoveries.

Biochemistry, Amino acid, and peptide bond

Proteins are linear polymers built from 20 different L-α-amino acids. All amino acids possess common structural features, including an α carbon to which an amino group, a carboxyl group, and a variable side chain are bonded. Only proline differs from this basic structure as it contains an unusual ring to the N-end amine group, which forces the CO–NH amide moiety into a fixed conformation. The side chains of the standard amino acids, detailed in the list of standard amino acids, have different chemical properties that produce three-dimensional protein structure and different reactivities, are therefore critical to protein function.

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The amino acids in a polypeptide chain are linked by peptide bonds. Once linked in the protein chain, an individual amino acid is called a residue, and the linked series of carbon, nitrogen, and oxygen atoms are known as the main chain or protein backbone. The peptide bond has two resonance forms that contribute some double-bond character and inhibit rotation around its axis, so that the alpha carbons are roughly coplanar. The other two dihedral angles in the peptide bond determine the local shape assumed by the protein backbone.

Due to the chemical structure of the individual amino acids, the protein chain has directionality. The end of the protein with a free carboxyl group is known as the C-terminus or carboxy terminus, whereas the end with a free amino group is known as the N-terminus or amino terminus.

The words protein, polypeptide, and peptide are a little ambiguous and can overlap in meaning. Protein is generally used to refer to the complete biological molecule in a stable conformation, whereas peptide is generally reserved for a short amino acid oligomers often lacking a stable three-dimensional structure. However, the boundary between the two is not well defined and usually lies near 20–30 residues. Polypeptide can refer to any single linear chain of amino acids, usually regardless of length, but often implies an absence of a defined conformation.

Proteins are assembled from amino acids using information encoded in genes.

Proteins are assembled from amino acids using information encoded in genes. Each protein has its own unique amino acid sequence that is specified by the nucleotide sequence of the gene encoding this protein. The genetic code is a set of three-nucleotide sets called codons and each three-nucleotide combination stands for an amino acid, for example AUG stands for methionine. Because DNA contains four nucleotides, the total number of possible codons is 64; hence, there is some redundancy in the genetic code, with some amino acids specified by more than one codon. Genes encoded in DNA are first transcribed into pre-messenger RNA (mRNA) by proteins such as RNA polymerase. Most organisms then process the pre-mRNA (also known as a primary transcript) using various forms of post-transcriptional modification to form the mature mRNA, which is then used as a template for protein synthesis by the ribosome. In prokaryotes the mRNA may either be used as soon as it is produced, or be bound by a ribosome after having moved away from the nucleoid. In contrast, eukaryotes make mRNA in the cell nucleus and then translocate it across the nuclear membrane into the cytoplasm, where protein synthesis then takes place. The rate of protein synthesis is higher in prokaryotes than eukaryotes and can reach up to 20 amino acids per second.

The process of synthesizing a protein from an mRNA template is known as translation. The mRNA is loaded onto the ribosome and is read three nucleotides at a time by matching each codon to its base pairing anticodon located on a transfer RNA molecule, which carries the amino acid corresponding to the codon it recognizes. The enzyme aminoacyl tRNA synthetase "charges" the tRNA molecules with the correct amino acids. The growing polypeptide is often termed the nascent chain. Proteins are always biosynthesized from N-terminus to C-terminus.

The size of a synthesized protein can be measured by the number of amino acids it contains and by its total molecular mass, which is normally reported in units of daltons (synonymous with atomic mass units), or the derivative unit kilodalton (kDa). Yeast proteins are on average 466 amino acids long and 53 kDa in mass. The largest known proteins are the titins, a component of the muscle sarcomere, with a molecular mass of almost 3,000 kDa and a total length of almost 27,000 amino acids.


Chemical synthesis
Short proteins can also be synthesized chemically by a family of methods known as peptide synthesis, which rely on organic synthesis techniques such as chemical ligation to produce peptides in high yield. Chemical synthesis allows for the introduction of non-natural amino acids into polypeptide chains, such as attachment of fluorescent probes to amino acid side chains. These methods are useful in laboratory biochemistry and cell biology, though generally not for commercial applications. Chemical synthesis is inefficient for polypeptides longer than about 300 amino acids, and the synthesized proteins may not readily assume their native tertiary structure. Most chemical synthesis methods proceed from C-terminus to N-terminus, opposite the biological reaction.

Structure of proteins,

Most proteins fold into unique 3-dimensional structures. The shape into which a protein naturally folds is known as its native state. Although many proteins can fold unassisted, simply through the chemical properties of their amino acids, others require the aid of molecular chaperones to fold into their native states. Biochemists often refer to four distinct aspects of a protein's structure:

Primary structure: the amino acid sequence
Secondary structure: regularly repeating local structures stabilized by hydrogen bonds. The most common examples are the alpha helix and beta sheet. Because secondary structures are local, many regions of different secondary structure can be present in the same protein molecule.
Tertiary structure: the overall shape of a single protein molecule; the spatial relationship of the secondary structures to one another. Tertiary structure is generally stabilized by nonlocal interactions, most commonly the formation of a hydrophobic core, but also through salt bridges, hydrogen bonds, disulfide bonds, and even post-translational modifications. The term "tertiary structure" is often used as synonymous with the term fold. The Tertiary structure is what controls the basic function of the protein.
Quaternary structure: the shape or structure that results from the interaction of more than one protein molecule, usually called protein subunits in this context, which function as part of the larger assembly or protein complex.
Proteins are not entirely rigid molecules. In addition to these levels of structure, proteins may shift between several related structures while they perform their functions. In the context of these functional rearrangements, these tertiary or quaternary structures are usually referred to as "conformations", and transitions between them are called conformational changes. Such changes are often induced by the binding of a substrate molecule to an enzyme's active site, or the physical region of the protein that participates in chemical catalysis. In solution all proteins also undergo variation in structure through thermal vibration and the collision with other molecules, see the animation on the right.


Molecular surface of several proteins showing their comparative sizes. From left to right are: immunoglobulin G (IgG, an antibody), hemoglobin, insulin (a hormone), adenylate kinase (an enzyme), and glutamine synthetase (an enzyme).Proteins can be informally divided into three main classes, which correlate with typical tertiary structures: globular proteins, fibrous proteins, and membrane proteins. Almost all globular proteins are soluble and many are enzymes. Fibrous proteins are often structural; membrane proteins often serve as receptors or provide channels for polar or charged molecules to pass through the cell membrane.

A special case of intramolecular hydrogen bonds within proteins, poorly shielded from water attack and hence promoting their own dehydration, are called dehydrons.


Structure determination
Discovering the tertiary structure of a protein, or the quaternary structure of its complexes, can provide important clues about how the protein performs its function. Common experimental methods of structure determination include X-ray crystallography and NMR spectroscopy, both of which can produce information at atomic resolution. Cryoelectron microscopy is used to produce lower-resolution structural information about very large protein complexes, including assembled viruses; a variant known as electron crystallography can also produce high-resolution information in some cases, especially for two-dimensional crystals of membrane proteins. Solved structures are usually deposited in the Protein Data Bank (PDB), a freely available resource from which structural data about thousands of proteins can be obtained in the form of Cartesian coordinates for each atom in the protein.

Many more gene sequences are known than protein structures. Further, the set of solved structures is biased toward proteins that can be easily subjected to the conditions required in X-ray crystallography, one of the major structure determination methods. In particular, globular proteins are comparatively easy to crystallize in preparation for X-ray crystallography. Membrane proteins, by contrast, are difficult to crystallize and are underrepresented in the PDB.Structural genomics initiatives have attempted to remedy these deficiencies by systematically solving representative structures of major fold classes. Protein structure prediction methods attempt to provide a means of generating a plausible structure for proteins whose structures have not been experimentally determined.

Proteins are the chief actors within the cell, said to be carrying out the duties specified by the information encoded in genes.

Proteins are the chief actors within the cell, said to be carrying out the duties specified by the information encoded in genes. With the exception of certain types of RNA, most other biological molecules are relatively inert elements upon which proteins act. Proteins make up half the dry weight of an Escherichia coli cell, whereas other macromolecules such as DNA and RNA make up only 3% and 20%, respectively. The set of proteins expressed in a particular cell or cell type is known as its proteome.


The enzyme hexokinase is shown as a simple ball-and-stick molecular model. To scale in the top right-hand corner are two of its substrates, ATP and glucose.The chief characteristic of proteins that allows their diverse set of functions is their ability to bind other molecules specifically and tightly. The region of the protein responsible for binding another molecule is known as the binding site and is often a depression or "pocket" on the molecular surface. This binding ability is mediated by the tertiary structure of the protein, which defines the binding site pocket, and by the chemical properties of the surrounding amino acids' side chains. Protein binding can be extraordinarily tight and specific; for example, the ribonuclease inhibitor protein binds to human angiogenin with a sub-femtomolar dissociation constant (<10-15 M) but does not bind at all to its amphibian homolog onconase (>1 M). Extremely minor chemical changes such as the addition of a single methyl group to a binding partner can sometimes suffice to nearly eliminate binding; for example, the aminoacyl tRNA synthetase specific to the amino acid valine discriminates against the very similar side chain of the amino acid isoleucine.

Proteins can bind to other proteins as well as to small-molecule substrates. When proteins bind specifically to other copies of the same molecule, they can oligomerize to form fibrils; this process occurs often in structural proteins that consist of globular monomers that self-associate to form rigid fibers. Protein-protein interactions also regulate enzymatic activity, control progression through the cell cycle, and allow the assembly of large protein complexes that carry out many closely related reactions with a common biological function. Proteins can also bind to, or even be integrated into, cell membranes. The ability of binding partners to induce conformational changes in proteins allows the construction of enormously complex signaling networks.