Glossary of Nutritional Terms
(M-R)
Compiled by Ron Avidan


The most complete glossary of bodybuilding, fitness, and supplement related nutritional terms and definitions. This is by no means a complete list, and is a work in progress. This information is for educational purposes only, and is not intended to replace any health care professionals. It is a compilation of many sources, mixed in with our opinions.


  • Ma Huang
    A herb that yields the stimulant Ephedra.

  • Maltitol
    This is a sugar alcohol that is used as a sweetener. It has half the caloric value of sucrose because it is not completely absorbed by the body.

  • Maltodextrin
    A long chain of glucose molecules (carbohydrates) that provides sustained energy without sharply increasing insulin levels. Essentially a chain of molecules of the simple sugar glucose linked together. There are an average of seven glucose molecules linked together to form a maltodextrin molecule.

  • Manganese
    Needed for normal tendon and bone structure.

  • Magnesium
    Mineral necessary for energy metabolism, protein and fat synthesis, neuromuscular transmission, amonia scavenging and binding of calcium to teeth, etc. Aids in bone growth, and is necessary for proper functioning of nerves and muscles.

  • Medium Chain Triglycerides (MCT)
    MCT's are technically fats, but they have very unique properties. The difference between them and other fats lies in their molecular structure. MCT's are shorter than other fats, which allows them to be burned rather quickly by the body for energy. MCT's enter the mitochondria, the powerhouse of a cell, without assistance, and do not require the usual transport mechanism.

    MCT's are an attractive supplement because of their calorie density. They have 9 calories per gram, like fats, but lack the disposition to be stored as fat. All fats are not created equal. Research shows that animals maintain a lower bodyfat when they use MCT's in place of traditional fats.

    They can help you increase lean muscle tissue, decrease excess bodyfat and fuel precompetition workouts.

  • Melatonin
    Hormone produced by the pineal gland that regulates circadian rhythms; helps induce sleep and acts as an antioxidant.

  • Methionine
    A sulfur bearing essential amino acid important in hair, nail and muscle production, liver maintenance (lipotropic effects), and production of creatine and other aminos.

  • Methoxyflavone
    Also called 5-methyl-7-methoxyisoflavone. A synthetic isoflavone that is highly anabolic, yet free of any androgenic effects. It halts the muscle wasting, and increases lean tissue growth. It increases calcium phosphorous, potassium and nutrogen retition to a significant degree.

  • Milk Thistle
    A herbal formula. Popular with bodybuilders because certain steroids are known to negatively impact the liver. Silymarin (the active ingredient of milk thistle) has been found to play a role in human regeneration of liver cells after damaged from alcohol, or liver disease, as a means for promoting would healing, and as a strong antoixidant. It also has been known to decrease elevated liver enzymes induced by certain type of drugs.

  • Mineral
    Inorganic substances necessary for good health as an ingrediant or a catalyst.

  • Mineral (Chelated)
    A chelated mineral is generally attached to a protein transporter molecule with the intent of improved transport across the gut to the blood stream. Although some of the minerals are well absorbed in this manner it does not necessarily always indicative of the best form for absorption.

  • Monounsaturated Fats
    An essential fatty acid (EFA) that seems to reduce the risk of cardiovascular disease. This is considered a type of 'good' fat. Olive oil, and canola oil have this in them. You need approxiamately 2% of your daily calories as EFA's.

  • N-Acetyl Cysteine
    A stable form of the essential amino acid L-cysteine. Cysteine is a precursor for glutathione, an important antioxidant in the body. Cysteine also serves as a major sulfur source for many body components.

  • NADH (Nicotinamide Adenine Dinucleotide)
    Also known as coenzyme 1, is the coenzymatic form of vitamin B3. NADH is involved in the production of energy in every cell. It supports healthly neurotransmitter functions.

  • Niacin (Vitamn B-3)
    A vitamin Important in carbohydrate metabolism, formation of testosterone and other hormones, formation of red blood cells and maintaining the integrity of all cells. Helps body utilize protein, fats, and carbohydrates. Necessary for a healthy nervous system and digestive system. It also lowers elevated blood cholesterol levels when taken in large amounts of more than 1,000 milligrams a day.

  • Norandrostenedione
    Naturally occuring prohormone that works in a manner similar to Androstenedione, however, results can be much better, and side effects less.

  • Norepinephrine
    A hormone produced by your adrenal glands. Important for many bodily activities, including brain function.

  • Nubain
    Bodybuilding steroid. Real name is Nalbuphine Hydrochloride. A lot of bodybuilders get addicted to Nubain, as it helps them relax or sleep better. It makes them feel like they can really relax, especially during the times when you are stressed before a contest preperation. You inject it.

  • Oil (Canola)
    Canola Oil is a good choice for bodybuilders seeking an oil low in saturated far. It has a fat profile of eight grams monounsaturated, four grams polysaturated, and only one gram of saturated fat per tablespoon. Monounsaturated fat contains Omega-3 fatty acids. At high temperatures, canola oil releases free radicals and loses its Omega-3 benefits.

  • Olestra
    A fake fat substitute. This will save you calories, but may also deplete your body of nutrients. If you use this product, or products containing this, make sure you good your 2% dose of essential fatty acids (EFA).

  • Omega-3 Fatty Acids
    An essential fatty acid (EFA) that seems to reduce the risk of cardiovascular disease. This is considered a type of 'good' fat. Sources include fish, salmon, mackerel, sardines. You need approxiamately 2% of your daily calories as EFA's.

  • Ornithine
    A non-essential, non-structural amino acid made from Arginine shown to influence growth hormone release: most anabolic when combined with alpha-ketoglutarate (OKG).

  • Paba (Para Aminobenzoic Acid)
    Important for the formation of red blood cells. Aids in the conversion of protein into energy. Necessary for healthy skin, and hair pigmentation.

  • Pantothenic Acid (Vitamin B-5)
    A vitamin which supports carbohydrate, protein and fat metabolism; hemoglobin synthesis. Helps release energy from protein, carbohydrates, and fat. Needed to support a variety of body functions, including the maintenance of a healthy digestive system.

  • Pectin
    A soluble fiber found in the skins of fruits (apples and peaches) and vegetables. One study found that eating Pectin will make you feel full longer. Researchers speculate that Pectin may slow digestin and keep food in your stomach longer.

  • Phaseolus Vulgaris
    An ingredient which has been shown to effectively prevent the body from absorbing up to 35 grams of unwanted starch per meal. It is found in white kidney beans.

  • Phenylalanine
    An amino acid, one of the main ingredients to enhance brain function. It has also been used to relieve stress.

  • Phosphatidylserine (PS)
    A phospholid. An ingredient which may block cortisol (a hormone which breaks down muscle cells into fuel). Alsom reported to increase levels of glucose, the brain's energy source.

  • Phosphorus
    Mineral that is structural component of all cells (including muscle); necessary for energy metabolism, protein synthesis, and growth / mainteneance of al tissues.

  • Polyphenols
    Polyphenols are potent and wide ranging in their physiological prperties. They are antioxidants, cancer preventatives, cavity and gingivitis preventatives, prebiotics and even internal deodorizers.

  • Potassium
    Mineral that helps maintain cellular integrity and water balance, nerve transmission and energy metabolism; necessary for muscle contraction. Potassium helps to lower blood pressure, lower risk of stroke, maintain muscle balance and prevent muscle cramping. Potassium helps to reduce the amount of sodium in the body.

  • Pregnenolone
    The "mother" steroid hormone from which most other steroid (sex) hormones are made, including DHEA. Has beneficial neurotransmitter effects.

  • Proanthocyanadins
    Potent antioxidant phytonutrient found in some pine needles (pycnogenol) and grape seeds and skins (grape seed extract), it is especially synergistic with vitamin C making them more powerful antioxidants together than by themselves.

  • Protein
    Primary macronutrient for growth and maintenance of our body's structural parts (including muscle). Cannot be stored, so must be replenished through diet. (1 gram=4 calories).

  • Protein (Egg)
    Source of protein with high Protein Efficiency Ratio, usually in egg white form (albumin) when used in protein powder to avoid cholesterol in egg yolk. Egg protein is the standard by which all other proteins are measured because of its very high ration of indispensable amino acids (also called essential amino acids because they must be supplied to the body from food or supplements) to dispensable amino acids.

  • Protein (Soy)
    Soy protein does not offer much benefits to a bodybuilder. Soy protein does not form a good curd in the stomach, thus making it a fast protein. The amino acid pattern in soy is inferior to that of milk proteins, and not as favorable toward promoting growth. However, it is a unique vegetarian protein that contains all of the Essential Amino Acids you need.

  • Protein (Whey)
    Dairy source of protein (other than cassein), known for high levels of BCAA's and high nitrogen retention. Made from milk curd, whey protein is the Rolls Royce of proteins because it has a superior amino acid composition (including high levels of leucine, arguably the most important branched chain amino acid), superior biological value (meaning that more of what you eat gets digested and into your system), is very low in lactose (a milk sugar that most adults have difficulty digesting).

  • Protein (Whey Hydrolyzed)
    When you hydrolyze whey protein, you permanently modify the native protein structure, meaning that the protein has been denatured. A denatured whey protein has little or no biological activity. The hydrolysis process breaks apart peptide bonds, which destroys the protein structure and the bital whey protein biological activity. However, you still get the amino acids of whey proteins from the hydrolyzed whey protein. Half the reason bodybuilders eat protein is to obtain these healthful smaller protein chains.

  • Protein (Whey Ion-Exchange)
    This special process revolved around the positive and negative charges or ion properties of whey protein. It featured the use of a resin to isolate the protein material from the whey. This is followed by ultrafiltration methods to furthur concentrate the protein. This contains 90% protein, and less than 1% lactose. True ion exchange whey protein is clear in a solution.

  • Protein (Whey Microfiltration)
    Microfiltration Whey Protein features filtering membranes with microscopic holes. This is also sometimes called Cross-Flow filtration, or Nanofiltration, depending on the size of the holes of the filtering membranes.

  • Protein (Whey Protein Concentrate)
    This type of protein contains 80% protein. The remaining 20% include moisture, lactose, fat and minerals. They have more 'fractions' and biologically active proteins than whey protein isolates. There is no difference between whey protein isolates and concentrates in the ability to spport muscle growth and recovery.

  • Protein (Whey Protein Isolate)
    This type of protein contains 90% protein, and about 10% moisture. There is almost no lactose and fat in this type of protein. They normally taste better, are easier to digest, and is much more expensive than Whey Protein Concentrate. There is no difference between whey protein isolates and concentrates in the ability to spport muscle growth and recovery.

  • Purslane
    It is a weed that is edible, and sometimes put on salads, mostly in Europe. It is loaded with linolenic acid, and omega-3 fatty acid that may help reduce the risk of heart attack, and improve the health of cell membranes in the eyes and brain. It is also an excellent source of Vitamin E, providing 6 times as much as spinach.

  • Pycnogenol
    Source of proanthocyanadins.

  • Pyridoxine (Vitamin B-6)
    A vitamin which supports glycogen and nitrogen metabolism; production and transport of amino acids; production and maintenance of red blood cells (hemoglobin) Essential for the body's utilization of protein. Needed for the production of red blood cells, nerve tissues, and antibodies. Women taking oral contraceptives have lower levels of B-6.

  • Pyruvate
    A key energy metabolite for the breakdown of fuel (glucose, fatty acids, amino acids, etc.) to energy in our bodies, pyruvate can give us increased energy, assist in burning fat as fuel, and have anticatabolic effects (such as producing alanine). Pyruvate acid is alpha - ketopropionic acid. Studies have shown that pyruvate can help decrease fatigue, and increase vigor with only six grams per day.

    The human body breaks down carbohydrates for energy though a process called glycolysis. As these sugars and starches are metabolized, pyruvate (pyruvic acid) is produced, which readily enters the mitochondria of cells to create energy fueling the muscles and other parts of the body.

  • Quercetin
    This bioflavonoid occurs in many plant foods. Quercitin has a synergistic effect with ephedrine and caffeine, increasing and prolonging their properties.

  • Retinol (Vitamin A)
    A vitamin with antioxidant properties, important for eye protection and bone growth; protein and hormone synthesis (including GH and testosterone); supports tissue maintenance. Helps reduce susceptibility to infection. Essential for healthy skin, good blood, strong bones and teeth, kidneys, bladder, lungs and membranes.

  • Riboflavin (Vitamin B-2)
    A vitamin which helps with energy production and amino acid production. Helps body obtain energy from protein, carbohydrates, and fats. Helps maintain good vision and healthy skin.

  • Ribose
    Ribose is a simple sugar that is extremely important in many processes in the body. Ribose is found in all living cells. It is the backbone of genetic material, and it is the starting point for production of ATP. Ribose effectively increases ATP and TAN (Total Adenine Nucleotide) recovery, while impriving performance in heart and muscle cells. Ribose also fortifies muscle ATP but through a different pathway than creatine. Ribose also bolsters muscle recovery after your train. Ribose promotes more effcient salvage pathway, thus allowing better ATP recycling and consequent increased muscular recovery after training. If the body does not use the salvage pathway, when ribose is insufficient, it must make ATP from scratch.