Raising the Sports Bar

May 2003

While a runner and his nutritionist wife conceived the first sports bar simply as a means to provide convenient energy during competition (a small market at the time), the demands of both the serious athlete and the weekend warrior have created a huge industry for these products based on functionality and taste. Long gone are the days of barely palatable, plastic-like pieces softened by body heat during competition to become something scarcely chewable. The trend now is toward a chocolate-enrobed, caramel-center-candy-like sports-nutrition bar, designed to deliver protein, carbohydrate, vitamins and amino acids to a wide-ranging consumer base.

The term “sports bar” can cover a variety of different areas, including the role of different supplements; the importance of carbohydrates, fats, flavor or protein; and the best bar for energy, muscle development or endurance. It’s hard to find bars targeted solely at sports, and determining if a benefit is fact from fiction is often difficult — if one individual decides on the benefits of a certain concept or mixture, it often becomes fact. Actual clinical trials, hard to find in the past, are now becoming the more responsible way to market a product. Collegiate, professional and Olympic athletic organizations have also become more active, providing better advice to athletes and discouraging the use of supplements that have not undergone thorough testing.

Bars have specialized and differentiated into mainstream specific nutritional delivery, weight-loss, specific athletic focus or general lifestyle. Consumer awareness has peaked, so tastes and/or textures are in the forefront, and competition has spurred innovation.

More than sports
Since most bars on the market are not sold strictly for the sports enthusiast, product divisions have started to overlap and blur. Many bars actually fit in more than one category, however these four can serve as a broad reference:

Carbohydrate/energy and endurance. Carbohydrates are key here — either as high glycemic delivery for immediate energy, or in a slow delivery form for consistent energy delivery over a span of time.
Low carbohydrate/high protein. The current market-leading nutritional bar is the Atkins Diet Advantage Bar™, which advocates controlling of carbohydrates to control weight. Bodybuilders also use high-protein bars to build muscle mass.

40:30:30. In everyday terms, it means 40% of calories as carbohydrates, 30% as protein and 30% as fat. Several versions of this approach are now on the market, from the Zone™ approach, to use of this approximate distribution for weight maintenance under other plans. However, a recent study released by The Ohio State University, Columbus, disputes the assertion that energy bars with low or moderate levels of carbohydrates help dieters lose weight. The investigators, led by Steven Hertzler, Ph.D., R.D., assistant professor of medical dietetics in the school of allied medical professions, found these bars don’t reduce insulin levels in the blood as much as manufacturers might claim. A lower insulin spike reportedly helps dieters burn fat more effectively to help lose weight. The complete study can be found in the Medical Science Monitor, vol. 9, issue 2, pp. 84-90. When examining a bar’s nutrition label, keep in mind that the percentages of carbohydrates, protein and fat are stated as a percentage of calories, an important concept.

Nutraceutical/gender- and disease-specific products. These may have some of the characteristics of the other groupings, but are targeted directly at certain markets, such as diabetics, women, supplement users, those who use organics and natural products, and kids.

Quick energy
Most bars in the carbohydrate/energy and endurance market are high-glycemic, quick and easy to digest. They are designed for runners, mountain bikers, triathletes, swimmers — anyone who might find themselves involved in competition where energy in a convenient form is key. The Australian Institute of Sport (AIS) defines them as “a tailor-made, purpose-built energy bar designed to cater to the added demands of athletes on the run.” The AIS, located in Canberra, Australia, goes on to stipulate that, in general, these bars contain 30 to 50 grams of carbohydrate per bar, 2 to 3 grams of fat, less than 5 to 15 grams of protein, plus about half the daily requirements of vitamins and minerals.

This category generally uses carbohydrate sources that deliver fast energy, such as corn syrups, rice syrups, fruit juices, dextrose and maltodextrins. High fructose corn syrup (HFCS), which combines a relatively low-glycemic fructose with glucose as energy sources, is also commonly used.

According to Jeff Billig, vice president, marketing, SPI Polyols, Inc., New Castle, DE: “Maltose is an energy source often over-looked. However, maltose, which is a disaccharide containing two glucose molecules, delivers an extremely high-glycemic response, providing a quick source of energy to the muscle. Maltose, since it is relatively low in molecular weight, can be easily used with higher-molecular-weight proteins to enhance the shelf life of the bar. Since maltose is only one-third the sweetness of sucrose, it can be used at any level without upsetting the flavor of the bar. Its low melt point makes it an ideal glaze and adherent for the outside of a bar or baked product.”

Another way to deliver fast energy is through medium-chain triglycerides (MCT). MCTs, with a chain length of C6 - C12, are metabolized differently than long-chain triglycerides (LCTs), which have a C14 - C24 chain. The body hydrolyzes LCTs, then re-esterifies them to triglycerides, and finally imports the triglycerides into chylomicrons that enter the lymphatic system. MCTs bypass the lymphatic system. They are hydrolyzed to medium-chain fatty acids, which are transported via the portal vein directly to the liver, where they are oxidized for energy. It’s unlikely that adipose tissue will store them as energy. For enteral and parenteral feeding, their advantage is already known. MCTs provide patients with an energy source similar to glucose, but with twice the caloric value.

Priming the muscle engine
Energy is stored in the body as glycogen, primarily in the muscle and the liver. Exercise rapidly depletes ATP-producers, such as creatine and stored glycogen, so the muscles need a steady supply of glucose to continue contraction at an optimum level. One of the goals of a training program is to increase the muscles’ capabilities to store glycogen, sometimes referred to as carbo-loading. This increases immediate energy reserves and also helps to increase recovery after exercise.

The muscles are fueled by adenosine triphosphate (ATP), which they can receive several ways. When exercise begins, the muscles quickly use up the available ATP they have stored, followed by what is available from creatine through the phosphocreatine pathway. The body can access glycogen stored in the liver through anaerobic glycolysis, but a byproduct of this pathway is lactic acid. Buildup of lactic acid can rapidly lead to muscle pain and exhaustion.

These pathways are critical to short-duration athletes, such as weightlifters, bodybuilders, sprinters and swimmers, because they provide maximum power output for a short span of time. Runners, triathletes and mountain bikers need to shift into aerobic glycolysis and lipolysis for the long haul. These pathways of ATP production are less efficient in terms of power, but they have no detrimental byproducts, and more calories are available through them. They require additional fuel during the exercise, but they keep up glycogen stores and keep supplying energy to the muscles.

The important thing to remember in extended competition is that external fuel is critical to aerobic glycolysis — cut off the fuel supply, and the body shifts back into anaerobic glycolysis, depleting glycogen stores and building up lactic acid. Most athletes have experienced the result of this build-up — the pain, exhaustion and dizziness associated with “hitting the wall.”

Part of an athlete’s training includes carbo-loading, but the carbohydrates stored in the muscle will not sustain an endurance athlete. According to the Indianapolis-based American College of Sports Medicine (ACSM), “for exercise lasting longer than one hour, consume 20 to 40 ounces per hour of cool fluids containing 30 to 60 grams (or 120 to 240 calories) of a 4% to 8% solution of carbohydrate and 300 to 600 mg of sodium.” Naturally, if people use sports bars to provide energy, they require hydration to replenish body fluids as well.

Pack in the protein
The low carbohydrate/high protein group is important to high-endurance sports, to sports based on muscle mass, and to the weight-reduction and weight-maintenance markets.
First, what about protein? Protein is one of the most essential nutrients in our body. It has a wide range of physiological functions necessary for achieving optimal physical performance. Protein forms the structural basis of muscle tissue, is a major source of energy for muscle contraction, and is also the major component of enzymes and blood in the muscle.

According to ACSM, “protein is the basic building material for muscle tissue, and it is required in higher amounts in the diets of individuals performing strength-training exercise.” The ACSM guidelines regarding protein intake state the following:
• to maintain muscle — 1.2 to 1.3 grams/kg/day;
• to build muscle — 1.5 to 1.6 grams/kg/day; and
• to gain muscle — 1.8 to 2.0 grams/kg/day.

Nutritional or sports bars most often contain protein derived from whey. Many bar manufacturers have developed their own unique blends of proteins based on whey protein concentrates (WPC) and whey protein isolates (WPI), plus soy proteins. WPCs contain 34% to 80% protein, depending on the concentrate chosen, while WPIs contribute more than 80%; typically greater than 90%.

According to K.J. Burrington, coordinator, whey applications program, Wisconsin Center for Dairy Research, Madison, WI: “Whey proteins are naturally high in the branched-chain amino acids (BCCA) leucine, isoleucine and valine. BCCAs are more readily absorbed by the body, and available for muscle building and muscle repair. Whey proteins contain all the essential amino acids the body requires. Whey proteins have a PDCAAS (Protein Digestibility Corrected Amino Acid Score) of 1.15, the highest of all the major food proteins, which includes egg, soy, beef and casein.” The PDCAAS is a measure of the protein quality of food proteins for humans and is recognized for labeling purposes by the FDA and the Food and Agricultural Organization/ World Health Organization (FAO/WHO). It is based on the protein’s amino-acid content, its digestibility and the requirements of a 2- to 5-year-old child.

During exercise, skeletal muscles utilize BCCAs from the blood to produce energy. Post-exercise protein consumption is also important — proteins, peptides and amino acids aid in both the repair and the growth of muscle tissue. Beyond this, whey proteins have been identified in recent studies as positive contributors in reduction of hypertension and suppression of appetite.

Soy protein is included in blends— and often as the sole protein source — because of soy isoflavones’ reported benefits, and because studies show that soy protein helps build and maintain muscle mass and lean body tissue. Although soy is lower in the essential amino acid methionine, it has a high concentration of the other essential amino acids — particularly arginine and glutamine — and so is considered a complete protein. The PDCAAS of soy protein is similar to dietary meat or fish, and slightly lower than egg, milk, casein, whey and bovine colostrum.

Gelatin hydrolysate has received press attention in consumer journals and the athletic press. This collagenous protein contains the essential amino acids glycine and proline in a concentration 20 times greater than other proteins. Both amino acids are important components of connective tissue, and ensure its firmness and elasticity. Studies show that gelatin hydrolysate has a regenerating and strengthening effect on bones and joints; therefore, product designers include it in the protein portion of a number of products.

Counting carbs
The focus on the role of carbohydrate in the human diet has resulted in more attention for low-carbohydrate sports bars. Generations of nutritionists have been trained to recognize “carbohydrate” as a relatively homogenous group. Historically, nutritionists have tested for fat, protein, moisture and ash, and then use the remaining “difference” to determine the carbohydrate percentage. Until the last several years, it became customary to express this “by difference” component as, simply, “total carbohydrates.”

The body, however, metabolizes this component in many different ways. “Total carbohydrates” contains all of the starches, sugars, gums, polyols, fibers, pectins, etc. — all carbohydrates, but all metabolized differently by the body. They have different glycemic and insulinemic impact, different caloric values, and different effects and benefits. How do these factors affect sports bars?

The bar industry is interested in the control of glycemic and insulinemic effects of different carbohydrates, and has promoted carbohydrate reduction as a positive. Some nutritionists have recognized that certain carbohydrates are metabolized differently (or not at all), meaning less glycogen is stored in the body. As a result, fat is used to produce energy.

A few manufacturers began labeling bars as “no-carb” or “zero-carb,” even though they were using low-glycemic polyols and glycerin. The FDA intervened, and the National Nutritional Foods Association (NNFA), Newport Beach, CA, issued a recommendation to report all carbohydrates under “total carbohydrates” on the nutritional panel, accompanied by the usual subheading for sugars, dietary fiber and sugar alcohols. The NNFA mentioned that manufacturers could use terms such as “effective carbohydrates,” “e carbohydrates,” “active carbohydrates” or “net carbohydrates” outside the nutritional panel to educate the consumer. These values are usually calculated by subtracting dietary fiber and sugar alcohols from total carbohydrates. Atkins Nutritionals, Inc., Ronkonkoma, NY, has instituted a NetCarb seal containing this number that, according to sources at Atkins, has been clinically verified.

So what are these low-glycemic carbohydrates, and why the sudden proliferation of their use? In short, the list includes sugar alcohols and dietary fibers (soluble and insoluble). The sudden proliferation might have resulted from an increase in available ingredients and a better understanding of their metabolism. In the last 10 to 15 years, the industry has seen an influx and increase in availability of more sugar alcohols and fibers, and the recognition of certain insoluble fibers (resistant starches) and soluble fibers (polydextrose; soluble dietary fibers derived from fruit, vegetable and grain).

Positive resistance
Past Food Product Design articles on fiber have covered resistant starches (RS) in greater depth. But to recap: Resistant starches escape digestion in the small intestine, but are fermented in the large intestine (most starches are easily digested in the digestive tract). These starches are classified as RS1, RS2 and RS3. RS1 starches are physically entrapped in partially milled seeds, grains or legumes. RS2 starches are intact, ungelatinized granules that are not easily gelatinized, and cannot be attacked by amylases until they have been gelatinized. Processing retrogrades RS3 starches, so that they are not easily gelatinized or attacked by enzymes.

Resistant starches do analyze as total dietary fiber by the AOAC methods 985.29 and 991.43. Although technically these starches are not fiber, they act as a “functional” fiber. While they could be viewed as insoluble fiber as analyzed by the methodology, RS have many physiological similarities to soluble fiber. They increase transit time in the GI tract, increase fecal bulk, and are fermented in the colon, releasing short-chain fatty acids.

According to Rhonda Witmer, business development manager of nutrition, National Starch and Chemical Co., Bridgewater, NJ: “Choices of carbohydrate foods with lower glycemic responses should be encouraged. We can help consumers make these healthy choices by developing foods with resistant starch. These foods minimize the increase in the glucose response in the blood stream, compared to similar foods made with white flour. In other words, we can essentially have our carbs and eat them too.

“Eleven human clinical trials have been published testing resistant starch from high-amylose corn starch and glycemic response,” notes Witmer, “and the results consistently show reduced glycemic index and reduced insulinemic index.” Commercial resistant starches contain 33% to 67% total dietary fiber (TDF) and are very low in water-binding capacity (WBC) versus other fibers, so they are very easily incorporated into most formulations. “Another important benefit,” she states, “is the production of short-chain fatty acids (SCFAs), principally butyrate, in the large intestine. Butyrate is essential for the integrity of colonic mucosa, and also induces the programmed cell death, or apoptosis, of tumor cells.”

Sugar-free solutions
Another class of low-glycemic carbohydrates is sugar alcohols, or polyols. These include maltitol, sorbitol, mannitol, hydrogenated starch hydrolysates (HSH), maltitol syrups, isomalt, lactitol, xylitol, erythritol and glycerin. Based on routes of metabolism and solubility, polyols are assimilated in different ways. All are suitable for use in sugar-free applications, and all produce lowered glycemic and insulinemic responses.

“Maltitol is a disaccharide derived from maltose,” states Edward Kuenzle, applications scientist, SPI Polyols “and it has many of the same physical and chemical characteristics of sucrose. Maltitol is an excellent sugar-free replacement for sucrose in chocolate compound coatings used in enrobing sports bars. Maltitol is very soluble, is not hygroscopic, has a low cooling effect similar to sucrose, and its caloric value is 2.1 kcal/gram, compared to 4.0 kcal/gram for sucrose.”

Many of the original protein bars faced a common problem — as moisture migration occurs within the product during shelf life, the protein quickly absorbs what little moisture is present, and the bar hardens over time. Many bar manufacturers use glycerin as a plasticiser, but glycerin does little to control this shelf-life problem.

Peter Jamieson, applications scientist, SPI Polyols, has studied the shelf-life differences of high-protein bars made with varying percentages of glycerin, HSH and maltitol syrups. “The problem,” he notes, “is that high-molecular-weight HSHs in many of these bars contribute to the structural density, and glycerin does not contribute moisture to help solve the problem. We have found that it is important to minimize glycerin and properly balance the MW (molecular weight) of the maltitol syrup with the protein to maintain the texture of the bar. It is important to control water activity, but is just as important to provide a certain amount of free moisture. This is also a problem in sugar-free caramel fillings — over time, moisture migrates, and the hardness and elasticity of the caramel increases. Selection of the right maltitol syrup will ensure minimal changes in texture over time.” Caramel has become one of the most popular layers in the more-candy-like sports-nutrition bars entering the market.

The 40:30:30 bars, depending on the bar, are designed for a variety of end purposes, and a number of different types can fit into this category. Carbohydrate sources can include corn syrup, fructose, glycerin, HFCS, polyols, maltodextrin, rice syrups and honey. Whey proteins and soy proteins are used alone or in proprietary blends.

Many of the bars in this category supply a balance of protein, carbohydrate, fat, B vitamins, and C and E vitamins supplied as antioxidants. Philip Katz, president, Schuster Laboratories, Canton, MA, notes: “Many of the meal-replacement bars have transitioned toward the tastes and textures of candy bars to appeal to the mass markets. Where most of the early products were found only in drug or sports stores, they can now be purchased in Wal-Marts, convenience stores and supermarkets. Nutritional bars are a huge market supplying many niches but, at some point, we will start to see consolidation in this market.”

Surveying supplements
The area of supplementation always sparks controversy, and most organizations do not encourage young athletes to take supplements. However, researchers are delving into the safety and efficiency of some of the “new” ingredients.

Creatine, previously mentioned in production of ATP for short-duration workouts, has received general acceptance and has shown positive effects in studies. Creatine is found in amino acids (glycine, arginine, and methionine) and is synthesized from these amino acids in the liver, pancreas and kidneys. In the muscle, creatine is converted to phosphocreatine, which is necessary for ATP production. Research shows that taking creatine supplements can increase muscle creatine by 20 to 30%. Increasing the amount of creatine found in the muscle also increases the amount of phosphocreatine, which aids in producing greater amounts of energy.

Conjugated linoleic acid (CLA) occurs naturally in beef and dairy products, and is also marketed as a powdered supplement. “Conjugated linoleic acid has been shown in animal and human studies to stimulate the breakdown of fat and to increase lean muscle mass. Especially in exercising individuals, this increases loss of weight coupled with increase of muscle mass,” says Patrick Luchsinger, marketing manager, Loders Croklaan Lipid Nutrition, Channahon, IL.

CLA has also been found to aid diabetics by lowering body mass as well as lowering blood sugar levels. Recent reports have indicated that higher amounts of CLA in the bloodstream lead to lower amounts of leptin, a hormone thought to regulate fat levels. This may be a positive in that high leptin levels may have a role in obesity.

The long-time debate over supplementation with carnitine still offers no clear-cut resolution. L-carnitine is believed to increase long-chain-fatty-acid oxidation in skeletal muscle during exercise. Advocates claim that it increases aerobic and anaerobic capacity, and promotes fat loss. Dietary sources of carnitine are meat and dairy products.

A controversial supplement increasingly in the news in recent years is the ergogenic ephedra. It contains several stimulants, including ephedrine and pseudoephedrine, and almost all the supplements combine ephedra with at least one other stimulant, usually caffeine or guarana (an herb-containing caffeine). Weight-loss supplements as well as energizing products often contain ephedra (also found in the herb ma huang), but increasing numbers of cases that show adverse effects indicate extreme caution is needed when considering its use. The side effects associated with these products are primarily cardiovascular-related. A review of FDA data on reported events linked to ephedra use indicates high blood pressure, stroke, heart attacks and death.

The Dallas-based American Heart Association (AHA) recently submitted comments to FDA supporting FDA’s proposal to limit the manufacturing and marketing of ephedra-based dietary supplements. AHA, referring only to over-the-counter dietary supplements — not prescription drugs containing ephedrine or over-the-counter “drugs” containing pseudo-ephedrine (such as many non-prescription cough and cold medicines) — further stated that FDA should ban dietary supplements containing ephedra. While FDA regulates over-the-counter drugs, relatively few standards or guidelines exist for the manufacture and marketing of dietary supplements.