Important electrolytes in the body, such as sodium, potassium, chloride and bicarbonate are essential for maintaining normal water distribution throughout the body, and are essential for heart, nerve and muscle function. Sweating causes the body to lose electrolytes, primarily sodium and chloride; i.e., salt. It is generally well accepted that the provision of electrolytes along with water is important in rehydration following exercise.There is also some concern that excess water consumption without electrolytes during prolonged exercise can be detrimental to some people by increasing the risk of developing a condition called hyponatremia (low blood sodium). The main ingredients of popular sports drinks are water, electrolytes and simple carbohydrates and they are designed to promote rehydration.
The B vitamins are important facilitators of cell metabolism and energy production. Maintaining adequate intakes of these essential nutrients is important to ward off deficiency and help maintain optimal energy production. B vitamins such as thiamin (B1), riboflavin (B2) and niacin (B3) are critical for operation of metabolic cycles in the body that generate ATP, the body’s energy currency. Other important B vitamins include folate and cobalamin (vitamin B12), which are involved with red blood cell production and cell division, as well as pyridoxine (vitamin B6), which is needed for protein synthesis.
L-carnitine is an amino acid that is synthesized from the amino acids lysine and methionine. Because it can be synthesized in the body, L-carnitine is usually not considered to be an essential nutrient and is used with exercise programs to reduce muscle soreness.
D ribose is a five-carbon sugar (pentose) found primarily in ribonucleic acid. It encourages ATP production, maintains energy levels and promotes recovery. Most of the body’s tissues, including the heart, are unable to produce ribose quickly enough to restore energy levels once they have fallen significantly. Intense exercise, muscle ischaemia or localised hypoxia can all overwhelm the renewal mechanisms of cellular energy. As a result, an imbalance occurs between energy supply and demand which leads to muscle stiffness, pain and weakness. D ribose helps maintain optimal levels of cellular energy and reduces the physiological consequences of a deficiency of cellular energy.
Branched Chain Amino Acids (BCAAs)
The branched chain amino acids (BCAAs) are leucine, isoleucine, and valine. BCAAs are considered essential amino acids because human beings cannot produce these amino acids and must be present in the diet. Some athletes say that branched chain amino acids help improve strength training results, as well as help to improve endurance and recovery.
Coenzyme Q10 (CoQ10) is an important nutrient in the human body. It is a fat-soluble vitamin-like compound that is also known as ubiquinone from the word ubiquitous, which means “everywhere.” CoQ10 plays a role in the production of energy within the mitochondria, and it is the enzymes that are involved in the production of adenosine triphosphate (ATP), which is the high-energy fuel for all living cells.
Magnesium is a co-factor in over 300 enzymatic reactions in the body, and is necessary for the transmission of nerve impulses, muscular activity, temperature regulation and detoxification reactions. It is required for the metabolism of carbohydrates, proteins and fats, as well as activity related to calcium, phosphorus, and vitamin C. It is vital for the health of nervous and muscular tissues throughout the body and is necessary for the synthesis of ATP and it facilitates the transport of potassium into cells. A deficiency of magnesium or potassium can result in fatigue.
N-acetyl-cysteine is the acetylated form of the amino acid cysteine and serves as a precursor for the synthesis of glutathione, a detoxifying agent in the body. Intensive exercise can generate large amounts of free radicals, which places increased stress on the body, which can degrade the immune system. NAC quenches free radicals, strengthens the immune system, which can lead to enhanced performance.
There are many trace elements, such as iron, copper, zinc and selenium that are important essential mineral nutrients. Maintaining proper trace mineral status is important to maximize oxygen transport capacity (iron), ATP generation (iron), and defense against the damaging effects of free radical production (zinc, copper and selenium). Women are particularly in need of iron and are at high risk of developing iron deficiency, which impairs hemoglobin synthesis in red blood cells, leading to reduced oxygen transport to tissues and the development of easy fatigability on exertion.
Potassium is one of the body’s three major electrolytes (the other two being sodium and chloride). They exist as fully dissociated ions and are the main particles responsible for osmotic pressure in body fluids. Potassium is the primary electrolyte functioning inside cells throughout the body and needs to be replaced after strenuous exercise for the proper functioning of muscle and energy recovery.
Beta-alanine is found in the normal diet in meat, especially poultry. This amino acid, along with the amino acid L-histidine, forms the dipeptide carnosine in muscle. Oral supplementation of beta-alanine can increase muscle carnosine concentration. Exercise normally produces acid in the body and can lead to a drop in pH. Carnosine acts as a buffer in muscle and can offset the exercise-associated drop in muscle pH and has been shown to improve physical performance.
Gamma-Aminobutyric Acid (GABA)
GABA is synthesized in the body from an amino acid called glutamate. GABA acts as an inhibitory neurotransmitter in the brain, which may help to prolong time to fatigue and increase glycogen content of muscle. GABA has also generated interest in the sports community because it may also influence secretion of growth hormones and thereby influence muscle growth.
Botanicals and Natural Products
The endurance and performance-related ingredients discussed above represent compounds that are either essential dietary nutrients needed for metabolism or are naturally produced substances in the body. Consumption of fortified food products or dietary supplements with added amounts of these compounds may augment normal production or levels of these molecules in the body leading to a positive energy and endurance benefit. There is also another important category of compounds that are not essential nutrients but are found in plants and can have a positive health or performance benefit. These phytochemicals can be incorporated into fortified products or supplements to help promote greater endurance and stamina. Some of the more common botanicals and phytochemicals that can be used for this purpose are discussed below.
Caffeine is the most commonly consumed dietary stimulant and is found as an ingredient in coffee, tea and cola drinks. In nature, caffeine is actually a natural insecticide and is found in over 60 different plants. Research suggests that caffeine does have important effects on exercise capacity and alertness. Caffeine is also found in many products specifically designed to produce energy and alertness, such as energy shots, energy drinks and various energy-promoting supplements.
Guarana is an increasingly popular ingredient from a South American plant found in the Amazon basin region, with a high concentration of caffeine in the seeds. This property has led to its inclusion in many energy shots or other energy-promoting beverage products. Due to its caffeine content, drinks containing guarana will help reduce fatigue and improve alertness. Beware, however, that energy drinks often contain additional caffeine as an ingredient and some caution should be used concerning excessive use. Adverse effects of excess caffeine, from any source, can increase heart rate, and cause irritability and tremors.
Ginseng has a long history of use for its health-promoting properties. Ginseng is used in energy drinks, along with other potential energy-boosting ingredients such as caffeine, glucose and guarana. However, there is little clear support for ginseng as an ergogenic aid in the scientific literature.
Flavonoids represent a large class of phytochemicals produced by plants, with the typical dietary intake of flavonoids in the United States being 200 mg/day. Sources of flavonoids include fruits and vegetables and tea. Flavonoids can have antioxidant effects, as well as other health benefits including anti-inflammatory effects that are likely to be beneficial, especially to the highly active individual or athlete.
Green Tea Catechins
Green tea is particularly popular as an ingredient in a variety of novel food products. It contains flavonoid compounds called catechins, especially EGCG (epigallocatechin 3-gallate), that have antioxidant properties and may lessen the deleterious effects of exercise. Some evidence suggests EGCG may also promote fat burning and improve VO2max during exercise.
Challenges in Formulating Functional Foods and Beverages for Endurance Nutrition
Just as we have many products on grocers’ shelves that promote a myriad of benefits for a multitude of health conditions, global, on-the-go lifestyles are creating an increased demand for nutritional products that strategically promotes endurance.
There are a host of considerations for food developers looking to incorporate specific nutrients into these products, a few of which include responsible examination of interactions as well as synergies between various ingredients. Certain ingredients, when used together may enhance their endurance-boosting effects more than would be expected when used individually.
Another important consideration is the delivery channel for these nutrients, as different demographics vary in food and beverage preferences. Nutrients perform and interact differently depending on how they are integrated and in what application. Various market forms may need to be explored, depending upon the end-use. Good practice calls for high quality nutritional blends that address these issues, which in turn will gain consumer confidence in the product and repeat purchase.
Additionally, sensory changes caused by functional food ingredients or any nutrient should be minimized at the beginning of the premix and finished product development phase, rather than later in the process.