Protein Controversies In Diabetes
Diabetes SpectrumVolume 13 Number 3, 2000, Page 132 Marion J. Franz, MS, RD, LD, CDE In Brief People with diabetes are frequently given advice about protein that has no scientific basis. In addition, although weight is lost when individuals follow a low-carbohydrate, high-protein diet, there is no evidence that such diets are followed long-term or that there is less recidivism than with other low-calorie diets. People with type 1 or type 2 diabetes who are in poor metabolic control may have increased protein requirements. However, the usual amount of protein consumed by people with diabetes adequately compensates for the increased protein catabolism. People with diabetes need adequate and accurate information about protein on which to base their food decisions. In the United States, ~16% of the average adult consumption of calories is from protein, and this has varied little from 1909 to the present.1 Protein intake is also fairly consistent across all ages from infancy to older age. A daily intake of 2,500 calories contributes ~100 g of protein—about twice what is needed to replace protein lost on a daily basis. Excess amino acids must be converted into other storage products or oxidized as fuel. Therefore, in theory, the excess ingested protein could, through the process of gluconeogenesis, produce glucose. This would mean that 100 g of protein could produce ~50 g of glucose. This has been the basis of the statement that if about half of ingested protein is converted to glucose, protein will have one-half the effect of carbohydrate on blood glucose levels. However, this belief has been challenged.2-4 Protein controversies exist either because research has not provided conclusive answers or because professionals are not aware of the research. This article will review Continue reading >>
How Insulin Really Works: It Causes Fat Storage…but Doesn’t Make You Fat
Many people believe that insulin is to blame for the obesity epidemic. When you understand how it actually works, you’ll know why this is a lie. Insulin has been taking quite a beating these days. If we’re to listen to some “experts,” it’s an evil hormone whose sole goal is making us fat, type 2 diabetics. Furthermore, we’re told that carbohydrates also are in on the conspiracy. By eating carbs, we open the insulin floodgates and wreak havoc in our bodies. How true are these claims, though? Does it really make sense that our bodies would come with an insidious mechanism to punish carbohydrate intake? Let’s find out. What is Insulin, Anyway? Insulin is a hormone, which means it’s a substance the body produces to affect the functions of organs or tissues, and it’s made and released into the blood by the pancreas. Insulin’s job is a very important one: when you eat food, it’s broken down into basic nutrients (protein breaks down into amino acids; dietary fats into fatty acids; and carbohydrates into glucose), which make their way into the bloodstream. These nutrients must then be moved from the blood into muscle and fat cells for use or storage, and that’s where insulin comes into play: it helps shuttle the nutrients into cells by “telling” the cells to open up and absorb them. So, whenever you eat food, your pancreas releases insulin into the blood. As the nutrients are slowly absorbed into cells, insulin levels drop, until finally all the nutrients are absorbed, and insulin levels then remain steady at a low, “baseline” level. This cycle occurs every time you eat food: amino acids, fatty acids, and/or glucose find their way into your blood, and they’re joined by additional insulin, which ushers them into cells. Once the job is done, insu Continue reading >>
Increasing Insulin Availability Does Not Augment Postprandial Muscle Protein Synthesis Rates In Healthy Young And Older Men
Skeletal muscle protein synthesis is highly responsive to food intake. It has been suggested that the postprandial increase in circulating insulin modulates the muscle protein synthetic response to feeding. The objective of the study was to investigate whether a greater postprandial rise in circulating insulin level increases amino acid uptake in muscle and augments postprandial muscle protein synthesis rates. Forty-eight healthy young (age 22 1 y; body mass index 22.0 0.3 kg/m2) and older males (age 68 1 y; body mass index 26.3 0.4 kg/m2) ingested 20 g intrinsically L-[1-13C]-leucine- and L-[1-13C]-phenylalanine-labeled casein protein with or without local insulin infusion. Primed continuous infusions of L-[1-13C]-leucine and L-[ring-2H5]-phenylalanine were applied, with arterial and venous blood samples and muscle biopsies being collected during a 5-hour postprandial period. Insulin administration did not increase overall leg blood flow (P = .509) but increased amino acid uptake over the leg in both young and older subjects (P = .003). The greater amino acid uptake over the leg did not further increase postprandial muscle protein synthesis rates (0.050% 0.006% and 0.037% 0.004% per hour vs 0.044% 0.004% and 0.037% 0.002% per hour in the insulin-stimulated vs control condition in the young and older groups, respectively; P = .804) and did not affect postprandial deposition of dietary protein-derived amino acids in de novo muscle protein (P = .872). Greater postprandial plasma insulin availability stimulates amino acid uptake over the leg but does not further augment postprandial muscle protein synthesis rates or stimulate the postprandial deposition of protein derived amino acids into de novo muscle protein in healthy young and older men. Skeletal muscle protein turno Continue reading >>
- Advice to walk after meals is more effective for lowering postprandial glycaemia in type 2 diabetes mellitus than advice that does not specify timing: a randomised crossover study
- The Effect of Walking on Postprandial Glycemic Excursion in Patients With Type 1 Diabetes and Healthy People
- Why Isn't Postprandial Insulin Assay Being Used to Predict Diabetes Onset?
Contribution Of Amino Acids And Insulin To Protein Anabolism During Meal Absorption.
Abstract The contribution of dietary amino acids and endogenous hyperinsulinemia to prandial protein anabolism still has not been established. To this end, leucine estimates ([1-14C]leucine infusion, plasma alpha-ketoisocaproic acid [KIC] specific activity [SA] as precursor pool SA) of whole-body protein kinetics and fractional secretory rates (FSRs) of albumin, fibrinogen, antithrombin III, and immunoglobulin G (IgG) were measured in three groups of healthy volunteers during intragastric infusion of water (controls, n = 5), liquid glucose-lipid-amino acid (AA) meal (meal+AA, n = 7), or isocaloric glucose-lipid meal (meal-AA, n = 7) that induced the same insulin response as the meal+AA. The results of this study demonstrate that 1) by increasing (P < 0.01) whole-body protein synthesis and decreasing (P < 0.01) proteolysis, dietary amino acids account for the largest part (approximately 90%) of postprandial protein anabolism; 2) the ingestion of an isocaloric meal deprived of amino acids exerts a modest protein anabolic effect (10% of postprandial protein anabolism) by decreasing amino acid oxidation and increasing (P < 0.01) albumin synthesis; 3) albumin FSR is increased (approximately 20%) by postprandial hyperinsulinemia (meal-AA) and additionally increased (approximately 50%) by amino acid intake (meal+AA); 4) IgG FSR is stimulated (approximately 40%) by amino acids, not by insulin; and 5) fibrinogen and antithrombin III FSR are not regulated by amino acids or insulin. Continue reading >>
- Early-onset and classical forms of type 2 diabetes show impaired expression of genes involved in muscle branched-chain amino acids metabolism
- Relative contribution of type 1 and type 2 diabetes loci to the genetic etiology of adult-onset, non-insulin-requiring autoimmune diabetes
- Best insulin injection sites: Absorption time and rotation
The Muscle-building Messenger: Your Complete Guide To Insulin
Years ago, insulin was only discussed in reference to diabetes. Insulin is the hormone that drives glucose out of the bloodstream and into cells, and diabetes is the loss of the ability to control blood glucose levels. Yet insulin is so much more than a hormone that controls glucose. For one, it's highly anabolic, which means it's critical for building muscle. Insulin also has a dark side, because it can increase fat storage. The challenge is to learn how to spike insulin to optimally recover from workouts and grow, while also blunting it to stay lean. Do you know all the facts about insulin and how to use it to your advantage? Don't be so sure. If not, my insulin guide will teach you how. Insulin And Muscle Insulin is actually a protein, and it is produced and released by the pancreas whenever you eat carbs, protein, or both. (That is, if the pancreas is working properly). Yet unlike the proteins that are the physical building blocks of muscle, this is a functional protein, much like growth hormone. Like all other proteins, insulin is a chain of amino acids strung together. But the way this protein chain is folded makes it act more like a signaling mechanism than a building block. From the pancreas, insulin enters the blood stream and travels to various tissues, including muscle tissue. The muscle fibers (or cells) are lined with insulin receptors, similar to a docking station. Once the insulin molecule docks onto the receptor, it signals the muscle cell to open up gates. This allows allow glucose, amino acids, and creatine to enter the muscles. This process is a major reason why insulin is so important for building muscle. Another reason is that when insulin docks onto the muscle cells, it instigates biochemical reactions in the muscle that increase protein synthesis, Continue reading >>
Insulin Response: It Comes From Eating Protein Too
It’s pretty well known that eating carbs causes an insulin release. But what many people don’t realize is protein causes a similar response. What is an insulin response? When we eat a meal, our digestive system breaks down food into nutrients that are absorbed into the bloodstream. Carbohydrates are broken down into sugars, which lead to an increase in blood sugar after consuming them. It’s this rise in blood sugar that triggers the release of the blood-sugar-lowering hormone, insulin. This process is known as an insulin response. This process is crucial because of the delicate balancing act we call blood sugar. The body likes to keep a tight reign on blood sugar as too low or too high can have deleterious effects. We often hear insulin and think "bad" when in fact it is absolutely essential for optimal health and function. Proteins are broken down into amino acids, which also stimulate an insulin response. However, the type of insulin response varies depending on the protein food source. Benefits and dangers of an insulin response The rise in insulin after eating helps move sugar into body tissues, and therefore keeps your blood sugar from getting too high. Note from Luke: Think of insulin as a traffic cop. It tells the blood sugar(glucose) where to go. In normal and healthy individuals the glucose fuels your nervous system, red blood cells, brain and muscle tissue. With optimal amounts and good insulin sensitivity, glucose fuels your nervous system and is burned off as energy. With too much or poor insulin sensitivity your muscle don't readily grab the glucose and it goes to where it's always welcome: fat stores. But the release of insulin can have negative effects. Too much insulin, for instance, can stress the pancreatic cells that secrete insulin. And this ad Continue reading >>
How To Help Your Body Absorb Protein
By admin on September 25, 2013 in Nutrition & Diet In order for your body to build muscle, produce hormones, and fight off viruses and bacteria, you need to get enough protein in your diet. Proteins are large, complex molecules comprised of long amino acid chains. These make up the structure of your bodys tissues and organs. Without protein, your body could not function properly. Unfortunately, the bodys ability to break down and absorb protein decreases with age. Countering this is not as easy as simply drinking more milk or having an extra egg with breakfast. Adjustments are required to compensate for poor protein absorption. Here are some great ways to improve the process. Your body cant absorb proteins in their natural state. Certain proteases in your stomach and pancreas break the bonds that hold the amino acids in protein together so your body can absorb the composite amino acids individually. To help with this process, try eating and drinking more acidic foods like orange juice, vinegar and most types of fruit. These contain proteases that can make your stomach a more acidic environment for breaking down protein. Pyridoxine is another name for vitamin B-6. Its primary purposes are to help enzymes break down protein and carry the dismantled amino acids to the blood stream. Vitamin B-6 is essential to get the most from your protein intake. Fortunately, if youre already trying to eat more protein, that means youre probably getting more vitamin B-6. Thats because both types of nutrients are found in meat, fish, nuts, seeds, beans, legumes and whole grains. Even after the body has broken down proteins into its simplest amino acid form, the work isnt done yet. How well your body utilizes these amino acids dictates how you benefit from the protein-rich foods you eat. B Continue reading >>
Effect Of Insulin On Human Skeletal Muscle Protein Synthesis Is Modulated By Insulin-induced Changes In Muscle Blood Flow And Amino Acid Availability
Go to: Insulin promotes muscle anabolism, but it is still unclear whether it stimulates muscle protein synthesis in humans. We hypothesized that insulin can increase muscle protein synthesis only if it increases muscle amino acid availability. We measured muscle protein and amino acid metabolism using stable-isotope methodologies in 19 young healthy subjects at baseline and during insulin infusion in one leg at low (LD, 0.05), intermediate (ID, 0.15), or high (HD, 0.30 mU·min−1·100 ml−1) doses. Insulin was infused locally to induce muscle hyperinsulinemia within the physiological range while minimizing the systemic effects. Protein and amino acid kinetics across the leg were assessed using stable isotopes and muscle biopsies. The LD did not affect phenylalanine delivery to the muscle (−9 ± 18% change over baseline), muscle protein synthesis (16 ± 26%), breakdown, or net balance. The ID increased (P < 0.05) phenylalanine delivery (+63 ± 38%), muscle protein synthesis (+157 ± 54%), and net protein balance, with no change in breakdown. The HD did not change phenylalanine delivery (+12 ± 11%) or muscle protein synthesis (+9 ± 19%), and reduced muscle protein breakdown (−17 ± 15%), thus improving net muscle protein balance but to a lesser degree than the ID. Changes in muscle protein synthesis were strongly associated with changes in muscle blood flow and phenylalanine delivery and availability. In conclusion, physiological hyperinsulinemia promotes muscle protein synthesis as long as it concomitantly increases muscle blood flow, amino acid delivery and availability. Continue reading >>
What Factors Slow The Absorption Of Carbohydrates?
When carbohydrates are quickly digested and absorbed, they can cause spikes in your blood sugar levels. While there are some misconceptions about the effects of eating high-fat or high-protein foods along with carbohydrates, eating carbohydrates with fiber or foods containing certain other components can help slow carbohydrate absorption and minimize its effects on your blood sugar levels. Sugars are the most quickly absorbed type of carbohydrate, with starches a close second since it doesn’t take very long for your body to break the bonds between the many sugar molecules that form the starch. In contrast, the third type of carbohydrate, fiber, can slow down the emptying of your stomach and the absorption of sugars and starches. This is one of the reasons why foods made with whole grains are healthier than those made with refined grains, since refined grains have been stripped of much of their fiber. Fat and Carbohydrate Absorption Eating foods containing fat along with those containing carbohydrate isn’t a good way to slow down carbohydrate digestion. Although fat also slows down the emptying of the stomach and the absorption of sugar into your blood, it doesn’t seem to affect the amount of insulin released after consuming carbohydrates, according to a study published in “Diabetologia” in 1984. Because of this effect, diets high in fat may increase insulin resistance, which is a precursor to diabetes. Another study, published in the "European Journal of Clinical Nutrition" in 2005, found a similar effect, with added fat increasing insulin levels while slowing gastric emptying and decreasing blood sugar. Protein’s Potential Effects Although diabetics are sometimes advised to eat protein-rich foods along with those containing carbohydrates, protein doesn’t Continue reading >>
This article is about the insulin protein. For uses of insulin in treating diabetes, see insulin (medication). Not to be confused with Inulin. Insulin (from Latin insula, island) is a peptide hormone produced by beta cells of the pancreatic islets, and it is considered to be the main anabolic hormone of the body. It regulates the metabolism of carbohydrates, fats and protein by promoting the absorption of, especially, glucose from the blood into fat, liver and skeletal muscle cells. In these tissues the absorbed glucose is converted into either glycogen via glycogenesis or fats (triglycerides) via lipogenesis, or, in the case of the liver, into both. Glucose production and secretion by the liver is strongly inhibited by high concentrations of insulin in the blood. Circulating insulin also affects the synthesis of proteins in a wide variety of tissues. It is therefore an anabolic hormone, promoting the conversion of small molecules in the blood into large molecules inside the cells. Low insulin levels in the blood have the opposite effect by promoting widespread catabolism, especially of reserve body fat. Beta cells are sensitive to glucose concentrations, also known as blood sugar levels. When the glucose level is high, the beta cells secrete insulin into the blood; when glucose levels are low, secretion of insulin is inhibited. Their neighboring alpha cells, by taking their cues from the beta cells, secrete glucagon into the blood in the opposite manner: increased secretion when blood glucose is low, and decreased secretion when glucose concentrations are high. Glucagon, through stimulating the liver to release glucose by glycogenolysis and gluconeogenesis, has the opposite effect of insulin. The secretion of insulin and glucagon into the Continue reading >>
Physiologic Effects Of Insulin
Stand on a streetcorner and ask people if they know what insulin is, and many will reply, "Doesn't it have something to do with blood sugar?" Indeed, that is correct, but such a response is a bit like saying "Mozart? Wasn't he some kind of a musician?" Insulin is a key player in the control of intermediary metabolism, and the big picture is that it organizes the use of fuels for either storage or oxidation. Through these activities, insulin has profound effects on both carbohydrate and lipid metabolism, and significant influences on protein and mineral metabolism. Consequently, derangements in insulin signalling have widespread and devastating effects on many organs and tissues. The Insulin Receptor and Mechanism of Action Like the receptors for other protein hormones, the receptor for insulin is embedded in the plasma membrane. The insulin receptor is composed of two alpha subunits and two beta subunits linked by disulfide bonds. The alpha chains are entirely extracellular and house insulin binding domains, while the linked beta chains penetrate through the plasma membrane. The insulin receptor is a tyrosine kinase. In other words, it functions as an enzyme that transfers phosphate groups from ATP to tyrosine residues on intracellular target proteins. Binding of insulin to the alpha subunits causes the beta subunits to phosphorylate themselves (autophosphorylation), thus activating the catalytic activity of the receptor. The activated receptor then phosphorylates a number of intracellular proteins, which in turn alters their activity, thereby generating a biological response. Several intracellular proteins have been identified as phosphorylation substrates for the insulin receptor, the best-studied of which is insulin receptor substrate 1 or IRS-1. When IRS-1 is activa Continue reading >>
Does Mixing Proteins With Carbs Reduce Insulin Response?
After eating a meal, the digestive system breaks foods down into nutrients that are absorbed into the bloodstream. Carbohydrates, broken down into sugars, cause an increase in blood sugar after meals. Rising blood sugar triggers secretion of the blood-sugar-lowering hormone insulin. This is called insulin response. Dietary proteins, broken down into amino acids, also stimulate the insulin response. However, the insulin response triggered by protein varies, depending on the food source. Additionally, the insulin response differs depending on whether the person has diabetes or not. While mixing protein with carbohydrate triggers an additive effect on insulin release, it is not clear whether this is helpful for people with diabetes. Video of the Day A rise in insulin after eating helps move sugar into body tissues, thereby keeping blood sugar from getting too high. However, excessive insulin secretion can have negative effects. Along with other factors, too much insulin may stress the pancreatic cells that secrete insulin. The exhausted cells can stop releasing insulin normally or die, which is detrimental because the body needs insulin to maintain normal blood sugar levels. Therefore, achieving a desirable level of insulin response that lowers blood sugar without exerting any adverse effects is essential. Classifying Foods by Insulin Response Foods have different effects on the insulin response, largely based on the relative concentration of carbohydrate, protein and, to a lesser extent, fat. The food insulin index (FII) classifies foods according to their after-meal insulin response. An August 2009 article published in the "American Journal of Clinical Nutrition" showed that refined cereals, sweets and potatoes have the highest FII, whereas nuts, beans and proteins have Continue reading >>
Manipulating Insulin Levels To Build More Muscle And Burn Fat!
Some diets even have you cutting out carbohydrates altogether to control insulin levels. Thus, the question is, when and how is insulin responsible for both? The hormone insulin has been heavily discussed in the bodybuilding and health communities. Many people speak of controlling blood sugar and insulin levels to build the most muscle naturally and to prevent fat storage. Insulin is a peptide hormone that is released from the beta cells of the pancreas. Some diets even have you cutting out carbohydrates altogether to control insulin levels. Thus, the question is, when and how is insulin responsible for both? When Insulin Is Released Insulin is released due to a rise in the body's blood sugar level that is induced mainly by your eating carbohydrates and protein. Insulin is primarily responsible for the direction of energy metabolism after eating. Insulin helps regulate blood sugar levels and helps keep them in the proper range. Insulin binds to specific receptors in cell membranes and diffuses glucose into the cell. Insulin also helps activate glycogen synthase, a process in which glycogen is stored in muscle tissue. In this process, two-thirds of glycogen is stored in muscle tissue while one-third is stored in the liver. Liver glycogen is used primarily to help keep blood sugar levels at a stable level. Insulin causes glucose transport proteins to increase their activity, which allows for increased glucose uptake by muscle cells. Although insulin helps dispose of blood glucose by storing it as glycogen in muscle tissue and the liver, it can also convert the excess to fat. But then again, insulin can also shut off the fat-burning process. That makes insulin truly a double-edge sword. Many people don't know that insulin causes amino acid uptake into muscle tissue, giving Continue reading >>
Protein turnover is the balance between protein synthesis and protein degradation. Proteins are naturally occurring polymers made up of repeating units of 20 different amino acids and range from small peptide hormones of 8 to 10 residues to very large multi-chain complexes of several thousand amino acids. Protein synthesis occurs on ribosomes - large intracellular structures consisting of a small subunit (33 proteins, 1900 nucleotides of ribosomal RNA) and a large subunit (46 proteins, 4980 nucleotides of rRNA) - that move along the messenger RNA (mRNA) copy of the gene (DNA) that was transcribed. The process of protein synthesis is called translation where the mRNA is read in triplets (codons), each triplet directing the addition of an amino acid (via its specific transfer RNA (tRNA)) to the growing polypeptide chain. The assembly of new proteins requires a source of amino acids which come from either the proteolytic breakdown (digestion) of proteins in the gastrointestinal tract or the degradation of proteins within the cell. Intracellular protein degradation is done by proteolytic enzymes called proteases and occurs generally in two cellular locations - lysosomes and proteosomes. Lysosomal proteases digest proteins of extracellular origin that have been taken up by the process of endocytosis. Proteosomes, which are large, barrel-shaped, ATP-dependent protein complexes, digest damaged or unneeded intracellular proteins that have been marked for destruction by the covalent attachment of chains of a small protein, ubiquitin. In contrast to the situation with glucose and fatty acids, amino acids in excess of those needed for biosynthesis cannot be stored and are not excreted. Rather, surplus amino acids are used as metabolic fuel. Most of the amino groups of surplus amin Continue reading >>
Is Insulin Required To Digest Proteins & Fats?
Insulin is a peptide harmone, which does not directly involve in digestion of any macromolecules. insteed it act indirectly as peptide signalling harmone, what it does is it goes and binds the receptors on the cell surface and stimulates them to uptake glucose from the bloodstream into the inside of cell to undergo oxidative brakdown of glucose in to carbon dioxide and water and energy. apart from this it doesn't stimulate uptake of any other biomolecules from blood stream except glucose. in diabetic absence of insulin, results in not activation of cells to uptake glucose from blood, hence glucose remains more and undigested in blood itself, hence this condition is called glucosemia (increased blood glucose) above the normal, which is detrimental. Insulin is an anabolic hormone mainly affecting the carbohydrate metabolism. As such insulin is not involved in digestion process but yes it is involved in the metabolism of fat and proteins also. Insulin has several actions: 1. It causes the cells in the liver, muscle, and fat tissue to take up glucose from blood and convert it to glycogen that can be stored in the liver and muscles 2. Insulin also prevents the utilization of fat as an energy source. In absence of insulin or in conditions where insulin is low glucose is not taken up by body cells, and the body begins to use fat as an energy source 3. Insulin regulates the amino acid uptake by body cells. Continue reading >>