Patent Description:
It is currently believed that improved sports performance can be attained by the intake of so-called sport drinks. These are usually non-carbonated and frequently contain fructose or other sugars, and complex carbohydrates, which are easily absorbed by the body, and are designed to promote the availability of energy and/or prevent or treat mild dehydration. Sport drinks also contain electrolytes (mainly sodium and potassium salts) and nutrients (proteins and amino acids). Sport drinks, energy drinks and other liquid, semi-solid and solid products, while marketed for athletes, are also consumed by non-athletes, as a snack, in situations where extra energy and endurance is desired.

Sometimes a distinction is made between sport drinks and energy drinks, the former tending to be more isotonic, and the latter containing more sugar and frequently also caffeine. In this context, no such distinction is intended, and the term "performance enhancing food or food supplement" includes sport drinks and energy drinks, as well as other liquid, semi-solid or solid forms, such as energy bars, tablets etc. as described in further detail below.

Physiological adaptation to exercise however involves major cardiovascular and metabolic changes. Oxygen consumption increases dramatically in the active muscles with a parallel increase in muscle blood flow. In these processes the endogenous gas nitric oxide (NO) plays an important regulatory role. NO increases blood flow to the muscles and modulates muscular contraction and glucose uptake (for review see <NPL>).

In addition, NO is involved in control of cellular respiration through interaction with enzymes of the mitochondrial respiratory chain (for review see <NPL>).

In vitro studies published in the <NUM> show that NO is a modulator of mitochondrial respiration via reversible inhibition of cytochrome c oxidase (<NPL>. ; <NPL>; <NPL>; <NPL>; and <NPL>).

NO may also interact at other sites of the mitochondrial respiratory chain and in the Krebs cycle (for review see Moncada, supra). While this important action of NO has been very well characterised in cell cultures, less is known about its physiological relevance in vivo and the effects of NO on cellular respiration during physical exercise. Shen and colleagues showed that administration of NOS-inhibitors in vivo during submaximal exercise leads to increased oxygen consumption in dogs (<NPL>) and Lacerda and colleagues showed similar results in rats (<NPL>). The majority of studies have been done using NOS-inhibitors while the effects of administering exogenous NO on exercise are largely unknown. In addition, studies in healthy humans are scarce.

The classical means by which NO production occurs is the L-arginine pathway, where NO is synthesized by specific enzymes, the NO-synthases. A fundamentally different alternative way of generating NO has been described more recently (<NPL>; <NPL>; <NPL>; and <NPL>). In this NOS-independent pathway the inorganic anions nitrate (NO<NUM>-) and nitrite (NO<NUM>-) are reduced in vivo to form NO. Dietary nitrate (found mainly in green leafy vegetables) (<NPL>; and Weitzberg, <NUM>, supra) is absorbed from the circulation by the salivary glands, secreted in saliva and partly converted to nitrite in the oral cavity by nitrate reducing bacteria. Swallowed nitrite can then enter the systemic circulation. Indeed, a recent study shows that ingestion of nitrate results in a sustained increase in circulating nitrite levels (<NPL>). Further reduction of nitrite into bioactive NO can occur spontaneously in acidic or reducing environments (Benjamin et al. <NUM>, supra, Lundberg et al. <NUM>, supra) but is also greatly enhanced by various proteins and enzymes including deoxyhemoglobin in blood (<NPL>), deoxymyoglobin (<NPL>), xanthine oxidase (<NPL>) and possibly by enzymes of the mitochondrial respiratory chain (for review see <NPL>; <NPL>; and <NPL>). NOS-independent NO production seems to complement the endogenous NO production especially during ischemia and acidosis when oxygen availability is low and the NO synthases operate poorly (Zweier et al. <NUM>, supra; Weitzberg et al, <NUM>, supra; <NPL>; Lundberg et al, <NUM>, supra). Tissue acidosis and relative hypoxia is present also during physical exercise and in this metabolic state, bioactivation of nitrite is likely enhanced.

The available information on the role of NO in healthy subjects and in particular in athletes during work or exercise is both insufficient and contradictory. Interestingly, the marketing of some currently available food supplements for athletes and bodybuilders refer to the vasodilatory effect of NO. One example is "NoX2™" (Bodyonics, Ltd. , USA), a product said to contain arginine alpha-ketoglutarate (A-AKG) and arginine-ketoisocaproate (A-KIC) and allegedly capable of boosting short term nitric oxide levels. Other products contain L-arginine, from which NO is synthesized by the NOS enzymes, and the beneficial effects of NO are often referred to, however without offering more detailed explanations.

The relation between peak work rate and resting levels of nitrate in plasma and urine from subjects with different levels of physical fitness has been studied (<NPL>). A positive relationship between physical fitness and formation of NO at rest was found and it was hypothesised that this positive relationship helps to explain the beneficial effects of physical exercise on cardiovascular health. In the JUNGERSTEN study nitrate was used solely as a marker of NO production and the authors state several times that nitrate is a stable and inert end product of NO and that it is biologically inactive.

The present inventors set out to test if administration of dietary nitrate would lead to increased systemic storage pools of nitrite and if this dietary strategy would have an impact on various physiological and biochemical parameters during exercise.

<NPL>) investigated myocardial oxygen demand following the administration of isosorbide dinitrate, an organic nitrate.

<CIT> aims inter alia at reducing mortality associated with heart failure; and has investigated the effects of isosorbide dinitrate and/or isosorbide mononitrate. Like the above Crawford et al. article, also this reference is focused on the heart, and while using terms like "improving exercise tolerance" and "improving oxygen consumption" it is clear that increased oxygen consumption is desired. <CIT> defines improved oxygen consumption as follows: " An increase in a patient's oxygen consumption typically results in the patient's increased exercise tolerance and would imply that the patient would have an improved quality of life".

<CIT> concerns the production of health food based multivitamins using vegetables.

<NPL>) concerns a comparison between enelapril and isosorbide dinitrate in the treatment of chronic congestive heart failure, as evident from the title. Using these orgnic nitrates, COHN et al. observed a vasodilatory effect and increased oxygen consumption.

<CIT> and <CIT> disclose a comparison between enelapril and isosorbide dinitrate, an organic nitrate, and teach "improving oxygen consumption" which is manifested as increased oxygen consumption These documents are also concerned with isosorbide dinitrate, an organic nitrate. It is also noteworthy that in <CIT> and <CIT> isosorbide dinitrate is combined with hydralazine and not tested alone which makes comparison with inorganic nitrate even less relevant.

PERI et al. studied the effects of apple extracts on the NO release by human saliva at pH <NUM> (<NPL>.

DENG et al. investigated whether ethyl nitrite could be detected in vitro from the reaction of ethanol with peroxynitrite, as well as after administration of ethanol to mice.

In two scientific articles, SHIBATA et al. investigated the oxygen consumption by arteriolar walls in rat skeletal muscle (<NPL> and <NPL>).

The inventors surprisingly found that the performance of a mammal manifested as a reduced oxygen uptake (VO<NUM>) during exercise was enhanced by administering to said mammal a non-toxic amount of nitrate and/or nitrite. Based on this finding, the inventors present the use of inorganic nitrate and/or nitrite in an edible composition comprising a source of inorganic nitrate and/or nitrite for non-therapeutically enhancing exercise performance of a human, said enhanced performance manifested as reduced oxygen consumption (VO2) for the same amount of work, as defined in attached claim <NUM>. The following description is subject to this limitation.

The invention will be described in closer detail in the following description, examples, and non-limiting claims, with reference to the attached drawings in which:.

Before the present invention is described, it is to be understood that the terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims and equivalents thereof.

It must be noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

Also, the term "about" is used to indicate a deviation of +/- <NUM> % of the given value, preferably +/- <NUM> %, and most preferably +/- <NUM> % of the numeric values, where applicable.

The term "edible" in this context means non-toxic and possible to ingest, however not limited to particular modes of ingesting, such as drinking, chewing, applying to the oral cavity in various forms, such as, for example a spray or aerosol.

The term "functional food" relates to any fresh or processed food claimed to have a health-promoting and/or disease-preventing property beyond the basic nutritional function of supplying nutrients. Functional foods are sometimes called nutraceuticals. The general category includes processed food made from functional food ingredients, or fortified with health-promoting additives, like "vitamin-enriched" products, and also, fresh foods (e g vegetables) that have specific claims attached. Fermented foods with live cultures are often also considered to be functional foods with probiotic benefits.

The present inventors showed that dietary supplementation with inorganic nitrate results in a reduced VO<NUM> during physical exercise and a significant increase in muscular efficiency. These effects occurred without any increase in plasma lactate.

Based on their findings, the inventors present a novel use of inorganic nitrate and/or nitrite in an edible composition comprising a source of inorganic nitrate and/or nitrite for non-therapeutically enhancing exercise performance of a human, said enhanced performance manifested as reduced oxygen consumption (VO<NUM>) for the same amount of work, characterized by intake of the edible composition delivering a dose of <NUM> - <NUM> mmol inorganic nitrate/kg body weight of the human and/or <NUM>-<NUM>µmol inorganic nitrite/kg body weight of the human per <NUM>.

In an embodiment of the present invention non-pathogenic bacteria are added to the nitrate and/or nitrite-comprising composition or the composition containing a blend of nitrate/nitrite-rich and polyphenol-rich compounds as described below. The purpose is to further enhance the generation of bioactive compounds such as NO, nitroso adducts or chemically related compounds. This enhancement will also occur locally in the GI (gastrointestinal) tract via bacteria-dependent reduction of nitrate and nitrite to NO and other bioactive nitrogen oxides. The composition with added bacteria can be in the form of a drink such as a juice, a yoghurt, a milk-based drink or any other fermented food product. The composition with added bacteria can also be included in different types of functional food. Suitable bacteria are the so called probiotic bacteria, included but not limited to Lactobacilli (for example L. acidophilus, L. delbrueckii, L. helveticus, L. salivarius, L. curvatus, L. plantarum, L. buchneri, L. fermentum, L. reuteri) and Bifidobacteria species, for example, but not limited to, B. bifidum, B. lactis) and probiotic yeasts such a Saccharomyces boulardii. Suitable non-pathogenic bacteria are for example, but not limited to, Staphylococcus species, Actinomyces species and Rothia species. These microorganisms may also be included in "dry form" for example in tablets, capsules, bars an alike.

According to an embodiment of the invention, the source of inorganic nitrate and nitrite is chosen among a concentrate or an extract of nitrate or nitrite containing plants, vegetables, or fruits or an inorganic nitrate salt. Examples of nitrate and nitrite salts include but are not limited to sodium, potassium, calcium, zinc, arginine, and ammonium. Sodium and potassium salts are presently most preferred. The nitrite and nitrate salts may be of synthetic origin but may also be isolated from natural sources. Examples of vegetables rich in nitrates are green leafy vegetables, spinach, beetroot, fennel, lettuce, cabbage, Chinese cabbage and the like. Juices, pastes, concentrates etc of such vegetables are contemplated as suitable sources of nitrate. In one embodiment the nitrate in the inventive composition originates from beetroot.

Many vegetables and fruits are rich in polyphenols. Polyphenols are a group of chemical substances found in plants, characterized by the presence of more than one phenol group per molecule. Polyphenols are generally further subdivided into hydrolyzable tannins, which are gallic acid esters of glucose and other sugars; and phenylpropanoids, such as lignins, flavonoids, and condensed tannins. Thus, in one embodiment of the present invention the nitrate and/or nitrite comprising composition is mixed with a compound that contains high levels of polyphenols. The ratio nitrate comprising composition:polyphenol-rich compound should be chosen to obtain enough supply of nitrate. The nitrate and/or nitrite comprising composition should therefore be at least about <NUM>%, preferably at least about <NUM> %, more preferably at least about <NUM>%, even more preferably at least about <NUM> % and most preferably at least about <NUM>% or even more. It is contemplated that this combined product will have synergistic health promoting effects via potentiation of NO bioavailability. Polyphenols will enhance NO generation by several separate mechanisms highlighted in <FIG>. First, such agents can directly stimulate endogenous NO formation from NO synthase enzymes (<NUM> in <FIG>). Second, it is contemplated that these compounds will enhance the reduction of nitrite to bioactive NO due to the presence of reductive -OH groups on the phenol ring (<NUM> in <FIG>). Third, by acting as scavengers of free radicals such as superoxide, they prevent these radicals from interacting with (and destroying) NO and thereby NO becomes more long-lived (<NUM> in <FIG>). In addition to this, nitrite or its reaction products can interact with the polyphenol itself and modify it chemically via nitration or nitrosation reactions (4a in <FIG>). The resulting compound can act as a long-lived NO donor (4b in <FIG>). An additional effect is that the presence of polyphenols will divert the chemical reactions away from formation of potentially carcinogenic nitrosamines (<NUM> in <FIG>). Nitrates reaction product nitrite can react with amines to form nitrosamines but polyphenols will inhibit this reaction by a dual mechanism. First they help to rapidly reduce HNO<NUM> directly to NO thereby minimizing the formation of nitrosating species (N<NUM>O<NUM>, HNO<NUM>). Second, they can directly compete for nitrosation with the amines by being nitrosated themselves.

Examples of fruit and fruit juices rich in polyphenols include, but are not limited to, apple, pear, grapes, lemon, orange, lime, peach, pomegranate, grapefruit, kiwi, ginger, and pineapple. Berries and juice from berries are also usable including, but not limited to, blackberries, black raspberries, blueberries, cranberries, red raspberries, cherries, bog wortleberry, lingonberries, black elderberry, black chokeberry, black currant, blueberry, cloudberries, and strawberries. Other natural sources of polyphenols include, but are not limited to, vegetables such as carrots, chili, rhubarb, onions. In addition, cacao products (rich in flavanols), green or black tea, nuts, Yerba mate and coffee are all rich in polyphenols. It is contemplated that the combination of nitrate and a polyphenol rich product as described above will act synergistically to enhance NO formation in the body at the expense of detrimental compounds such as nitrosamines. The beneficial effects of this include i. a reduction in blood pressure. In one preferred embodiment the nitrate in the inventive composition originates from beetroot (such as beetroot juice) which is blended with one or several polyphenol-rich products. The ratio beetroot juice : polyphenol-rich compound should be chosen to obtain enough supply of nitrate and therefore the beetroot juice part should be at least about <NUM>%, preferably at least about <NUM> %, more preferably at least about <NUM>%, even more preferably at least about <NUM> % and most preferably at least about <NUM>%.

In another embodiment a low concentration of ethanol is added to the inventive composition, wherein the ethanol content is below about <NUM>% (v/v). It has surprisingly been found that ethanol even in very low concentrations can generate the potent vasodilator ethyl nitrite following reaction with physiological amounts of nitrite. The reaction is enhanced at acidic conditions such as in the gastric lumen. It is contemplated that ingestion of nitrate will lead to accumulation of nitrite in the saliva and the nitrite will react with ethanol in the stomach thereby forming ethyl nitrite. For example, if the inventive composition is in the form of a liquid the ethanol content should be below about <NUM> % (v/v), more preferably below about <NUM>% (v/v), and most preferable between about <NUM>-<NUM>% (v/v).

In an exemplary embodiment,a nitrate or nitrite salt (for example potassium nitrate or ammonium nitrate) or a natural nitrate source including a dried vegetable powder, is combined with liquorice for example in liquorice candies such as salty liquorice (ammonium chloride). The addition of polyphenols to this combination is also preferred. Liquorice is well known for its blood pressure elevating effects, and it is contemplated that the addition of nitrate/nitrite alone or in combination with a polyphenol will counteract this via the NO-mediated blood pressure lowering effect of these compounds. In particular a salt such as potassium nitrate, sodium nitrate or ammonium nitrate may be used to replace in part or in whole the salt content (such as sodium chloride or ammonium chloride) of the liquorice product.

The inventive composition preferably has the form of a liquid, a paste, a bar, a cake, a powder, a granulate, an effervescent tablet, a chewing gum, a tablet, a capsule, a lozenge, a fast-melting tablet or wafer, a sublingual tablet or a spray. Another composition is a nicotine-free smokeless tobacco and/or wet snuff. Such products can be manufactured using conventional methods practised in the food and beverage industry, or in pharmaceutical industry.

More preferably said composition is in the form of, or constitutes a part of, a food product, such as a liquid, a paste, a bar, a cake, a powder, or a granulate.

According to an exemplary embodiment, the composition according to the invention is prepared as a fermented food product, such as a yogurt or similar dairy or non-dairy product, comprising a source of nitrate and/or nitrite in addition to live bacteria capable of enhancing nitrate or nitrite reduction.

The present inventors consider presenting the composition to the market in the form of a sport drink, an energy drink, a sport bar, or an energy bar.

The energy bar may take on a variety of forms. For convenience, it is preferred that the energy food product be shaped like a box, square, cylinder, string, pie, sphere, triangle, or other format suitable for packaging, transportation, handling and eating.

According to an exemplary embodiment, the composition is presented to the market as a functional food product.

Products comprising the inorganic nitrate, nitrite or a combination thereof can easily be manufactured by persons skilled in the food, sweets and beverage industry or the pharmaceutical industry, and existing compositions supplemented with nitrate, nitrite and other combinations described herein in amounts according to this invention.

For example an energy bar according to the present invention may include, in addition to nitrate and optionally nitrite, also a variety of other components such as, for example, nuts, crisps, fruit pieces, chocolate, seeds, and the like. Preferred nuts are almonds, peanuts, hazelnuts, cashews, walnuts, pecans, brazil nuts, and the like. Crisp components include rice crisps, corn crisps, oats, wheat flakes, and the like. The chocolate can be any type of chocolate or chocolate like edible component in various forms, such as, for example, chocolate chips, chunks, flakes and the like. Non-limiting examples of seeds include sesame, sunflower, poppy, caraway, fennel and the like.

In one embodiment of the present invention a cacao product such as dark chocolate that is rich in flavanols is combined with a nitrate/nitrite-rich natural compound in a drink or a chocolate bar. One preferred nitrate-rich compound in this embodiment is rhubarb. Again, the nitrate will potentiate the effect of the flavanols via enhancement of NO formation as described above and in <FIG>.

Additionally, traditional food ingredients such as flavours and the like may be included. For example, additional ingredients may include natural and artificial flavours, sweeteners, salt, flavour enhancers, colour additives, emulsifiers, stabilizers, fats, preservatives, and the like.

Contamination of a nitrate/nitrite-containing food or drink with unwanted bacteria may result in a large accumulation of nitrite, due to nitrate reducing bacterial enzymes. Ingestion of high levels of nitrite may cause potentially serious methemoglobinemia. In one embodiment a nitrate-rich composition is mixed with a compound that inhibits unwanted bacterial growth. Such compound should be chosen so as not to affect the taste of the product negatively. Ideally, it should enhance the taste and at the same time increase the bioactivity of the product. One option is to acidify the inventive composition so that final pH is below about <NUM>, and most preferably between about pH <NUM>-<NUM>. This will inhibit and/or abolish bacterial growth. Suitable acidifying agents can be any agent that reduces pH and include artificial compounds as well as natural juices from e.g., but not limited to, lemon or lime, ascorbic acid, acetic acid, or vinegar (from apple, grapes or other fruits). It is contemplated that with the use of natural products a dual effect is achieved. Besides having an antibacterial effect, they are rich in polyphenols, which enhance the generation of bioactive NO from nitrate/nitrite in the vegetable drink. In one particular embodiment a nitrate-rich vegetable juice (e.g. beetroot juice) is mixed with a compound that inhibits bacterial growth.

According to an exemplary embodiment of the above use, nitrate and nitrite is used in a dose ratio interval of about <NUM>:<NUM> to about <NUM>:<NUM> (nitrate:nitrite), such as <NUM>:<NUM>, <NUM>:<NUM>, <NUM>:<NUM>, <NUM>:<NUM>, <NUM>:<NUM> and <NUM>:<NUM>. Preferably the dose ratio is about <NUM>:<NUM>.

According to an exemplary embodiment, said inorganic nitrite is used alone, without the presence of nitrate.

The composition of the present invention may be manufactured into liquids, pastes, bars, cakes, powders, granulates, effervescent tablets, tablets, capsules, lozenges, chewing gum, fast melting tablets or wafers, sublingual tablets, a spray or the like, using conventional methods practiced in the food, sweets and pharmaceutical industry.

The inventors also present a novel method for non-therapeutically enhancing the performance of a mammal, wherein inorganic nitrate and/or nitrite is administered to said mammal. Said mammal is chosen among a human, a horse, or a dog, preferably a human. The dose of nitrate is about <NUM> - <NUM> mmol sodium nitrate/kg bodyweight/day. Correspondingly, the dose of nitrite is about <NUM>-<NUM>µmol/kg bodyweight/day.

There is reason to believe that the observed effects of nitrate on physical performance involve initial reduction of nitrate to nitrite. Nitrate itself is believed to be biologically inert and cannot be metabolised by mammalian cells. However, after ingestion nitrate re-enters into the mouth via the salivary glands and is effectively reduced by commensal bacteria thereby forming nitrite. In contrast to nitrate the nitrite ion has recently been shown to possess a wide range of bioactivities.

The inventors noted an increase in plasma nitrite after the nitrate treatment period thereby confirming in vivo reduction of nitrate as described previously (LUNDBERG & GOVONI <NUM>, <NPL>). Another finding in support of nitrite being bioactive was its effective consumption during exercise in contrast to the unchanged levels of plasma nitrate. Ultimately the bioactivity of nitrite is likely related to its further reduction to NO and possibly other closely related nitrogen intermediates.

In addition, it has been recently suggested that nitrite itself may directly affect cellular signalling pathways (<NPL>). Although probably unlikely, at this early stage, effects of the nitrate ion itself cannot be excluded. There are several principal ways by which biological effects of nitrogen oxides may be propagated including alteration of protein function by nitrosylation, nitration or direct binding to protein heme-moieties as in the prototypic activation of guanylyl cyclase by NO.

Earlier studies using NOS inhibitors to block endogenous NO production give some indications. NOS-inhibition has been shown to increase submaximal VO<NUM> in dogs during exercise, independently of the reduction in blood flow (<NPL>. ; SHEN et al. <NUM>, supra). The increase in VO<NUM> during NOS-blockade has been explained by the fact that NO affects tissue respiration by reversible inhibition of the respiratory enzyme cytochrome c oxidase (CARR & FERGUSON <NUM>, supra; BOLANOS et al. <NUM>, supra; BROWN & COOPER <NUM>, CLEETER et al. <NUM>, SCHWEIZER & RICHTER <NUM>). Others have related the increased VO<NUM> during NOS-blockade to an inhibiting effect of NO on proton leakage over the inner mitochondrial membrane (<NPL>; <NPL>; <NPL>). If the effects of nitrate were solely due to inhibition of cytochrome c oxidase one would expect an increase in anaerobic metabolism during physical exercise and a larger accumulation of lactate. However, judging from the results this was not the case, as the plasma lactate concentration was near identical after nitrate supplementation compared to placebo. The inventors consider this to be very surprising.

The studies using NOS inhibitors cited above all imply that endogenous NO is involved in regulation of oxygen consumption but there have been few attempts to study the effect of exogenous NO delivery. Studies with NO-donors such as nitroprusside and nitroglycerine have shown somewhat diverging results, with decreases in VO<NUM> in some cases (<NPL>; <NPL>), no effect in one study (<NPL>) and increases in other settings (<NPL>).

Several of the proposed mechanisms for nitrite reduction to NO described above could theoretically come into play during physical exercise. Thus, all these pathways are greatly enhanced during hypoxia and when pH decreases such as in a working muscle. Shiva and colleagues very recently demonstrated deoxymyoglobin-dependent nitrite reduction to NO in rat heart homogenates with a concomitant inhibition of mitochondrial respiration (SHIVA et al <NUM>, supra). Another possible pathway includes NO formation by the mitochondria themselves (<NPL>) or even simple acidic reduction of nitrite in the working muscle (Zweier et al. <NUM>, supra, <NPL>). Cosby and colleagues described NO formation and vasodilation from the reaction of circulating nitrite ions with deoxyhemoglobin in blood (<NPL>). While this latter pathway, and possibly also tissue nitrite reduction, very well might explain the recently described nitrate-induced reduction in resting blood pressure (Larsen et al. <NUM>), it is still not obvious how this NO also would decrease oxygen consumption in the working muscle. Thus, an effective inhibition of mitochondrial respiration e.g. by deoxymyoglobin-derived NO, would again be expected to result in accumulation of plasma lactate which was not the case.

The efficiency of the muscles to produce work has been related to the percentage of type I muscle fibres (<NPL>) and uncoupling protein-<NUM> (UCP3) content of muscle fibres (<NPL>). Other factors that might contribute to the efficiency of movement are anatomical, biochemical and biomechanical features (<NPL>). Thus, simply measuring differences in VO<NUM> at different work rates is not an optimal estimate of muscular efficiency because the energy output for a certain VO<NUM> is dependent upon substrate utilization. Gross efficiency (GE) calculations include possible changes in respiratory exchange ratio and thereby take substrate utilization into account. The improved GE after nitrate supplementation indicates better efficiency, but even so, it cannot be excluded that this improved efficiency originates from reduced baseline energy expenditure (EE). The Delta efficiency (DE) calculations are not dependent on the baseline EE and are also based on all work rates taken together instead of a single work rate at a time as in the GE-calculations. It is therefore plausible to expect DE to be the most valid estimate of muscular efficiency in this case. Indeed, even DE was significantly improved after nitrate supplementation. It is unlikely that the improved efficiency by nitrate comes from mechanical factors. The subjects of this study were all cyclists with many years of experience of training and competing. It is improbable that a few visits to the laboratory would change their efficiency during cycling to any noteworthy extent. Especially since the subjects used the same cycling shoes, clip-on pedals, and the same seat position as they where used to during training makes this even more unlikely. More important, the randomization procedure used in this study rules out any such differences. Marcheal and Gailly (<NPL>) demonstrated a faster relaxing velocity of muscle fibres in in situ experiments during administration of an NO-donor, thereby implicating a neuromuscular modulatory effect of NO. It remains to be proven if this can improve the muscular efficiency during cycling.

The finding that the oxygen pulse at a given work rate decreases by nitrate supplementation is a direct effect of the lower oxygen demand at that work rate. However, there is no difference in oxygen pulse at a given absolute oxygen uptake. The lack of effect of nitrate on VE/VO<NUM> or oxygen pulse indicates that the improved efficiency originates from muscular or mitochondrial adaptations rather than from central adaptations in the heart or the lungs.

In summary, the present findings demonstrate a lower oxygen cost during submaximal work after dietary supplementation with nitrate, in amounts achievable through the intake of a non-toxic amount of nitrite. This occurred without an accompanying increase in plasma lactate, indicating that the energy production had become more efficient. The mechanism of action and main targets need to be clarified but the process likely involves in vivo reduction of nitrate into bioactive nitrogen oxides including nitrite and NO.

Nine healthy, well-trained (VO2peak <NUM> +/-<NUM> x kg-<NUM> x min-<NUM>), males (<NUM> +/-<NUM> years) volunteered for the study. All subjects were trained cyclists or triathletes and well accustomed to the testing procedure. The inventors in this study chose to use well-trained subjects to avoid training effects from the tests such as enhanced VO2peak or better mechanical efficiency during submaximal exercise. The protocol was approved by the regional ethics committee in Stockholm and all subjects gave their written consent prior to participation.

The aim with the present study was to investigate the effects of two distinct dietary patterns, one with higher, and one with lower- than-normal nitrate intake. The study had a double-blind placebo-controlled cross-over design. During two three-day periods, separated by a washout interval of ten days, the subjects were instructed to avoid all foods with moderate or high nitrate content (all vegetables, all cured meats, strawberries, grapes, and tea). In addition, they were told to restrain from alcohol and tobacco products. Otherwise they were free to eat any food they liked during the three days of restricted diet. The subjects were randomized to start with either ingestion of <NUM> mmol sodium nitrate/kg bodyweight/day dissolved in water or an equal amount of sodium chloride (placebo). The daily dose was divided and ingested three times daily. The different solutions could not be distinguished by taste or appearance. The daily nitrate dose corresponded to the amount normally found in <NUM>-<NUM> gram of a nitrate-rich vegetable such as spinach, lettuce, or beetroot (Lundberg et al. , <NUM>, supra). The last dose of nitrate or placebo was ingested in the morning on the day of measurement (see the main tests below). The order between the nitrate supplementation period (NIT) and the placebo period (CON) was balanced. During the washout period the subjects did not adhere to any specific dietary regime.

Measurements were carried out on an electrically braked cycle ergometer (Monark 839E™, MONARK EXERCISE AB, Vansbro, Sweden) that was modified with a racing saddle and the pedal system the subjects were familiar with from training. The bicycle ergometer was computer-controlled, permitting a constant work rate regardless of the cadence the subject chose to pedal with. The pedalling cadence was individually chosen in the range of <NUM>-<NUM> rpm but kept constant during the test to minimize differences in work output due to changes in muscle recruitment patterns.

Pulmonary ventilation (VE), oxygen uptake (VO<NUM>), CO<NUM> output (VCO<NUM>) and respiratory exchange ratio (RER) were measured at <NUM> second intervals by a computerised gas analyser (AMIS <NUM>, INNOVISION AS, Odense, Denmark) connected to a flow meter which the subjects breathed through via a mouthpiece and a plastic tube. Heart rate (HR) was continuously recorded during the tests with a portable heart rate monitor (Polar S610™, POLAR OY, Kempele, Finland). Capillary blood samples (20ul) were collected from the fingertip and were analyzed for lactate ([Hla]) using a Biosen C-Line Sport Analyser (EKF-diagnostic GmbH, Magdeburg, Germany). Haemoglobin concentration ([Hb]) at rest was determined with capillary blood taken from the fingertip and analyzed with an Hb-measuring device (HEMOCUE AB, Ängelholm, Sweden). Hematocrit (Hct) was determined by centrifuging capillary blood at <NUM> rpm for three minutes.

Each subject attended the laboratory twice within a two-week period before the first main tests. The first pre-test was carried out to familiarize the subject with the bicycle ergometer and the testing procedure. The subjects did a preliminary test at five submaximal levels with every level lasting for five minutes. There was no rest between the different submaximal levels. VO<NUM> was continuously measured with the AMIS <NUM> analyzer. At the end of each submaximal level capillary blood was taken from the fingertip and later analysed for [Hla]. At every work rate the subjects rated their perceived exertion on the Borg's RPE-scale (<NPL>), both central and muscular exertion were rated. After eight minutes of recovery, the subject was instructed to cycle for as long as possible at a work rate corresponding to his calculated maximal oxygen uptake (<NPL>). During this test the subjects actual VO2peak was measured and if the subject was able to cycle for longer than seven minutes extra power of <NUM>-<NUM> watts was added every minute until exhaustion. One and three minutes after the maximal test capillary blood were sampled from the fingertip for analysis of [Hla].

Before the second pre-test, the submaximal levels were adjusted so that they corresponded to <NUM>, <NUM>, <NUM>, <NUM> and <NUM>% of VO2peak. The maximal work rate was also adjusted, if necessary, so that the time to exhaustion was kept between four and seven minutes.

The subjects refrained from heavy exercise three days prior to the main tests and avoided all exercise the day before the tests. They were also told to eat their last light meal at least <NUM> hours before the start of the tests. When the subjects came to the laboratory they received their last dose of either placebo or nitrate and were allowed to rest in the supine position for <NUM> minutes before the test commenced.

All subjects used a standardised warm up procedure of five min of cycling at <NUM> watts followed by five minutes of rest. The submaximal and maximal tests were performed in the same way as the second pre-test with five submaximal work rates lasting five minutes each, without rest between the different levels. Identical work rates were used during the two main tests. Venous blood (<NUM>) was drawn at rest <NUM> minutes after the last nitrate/placebo-dose was ingested and again immediately after the VO2peak-test. The blood was placed in an ice bath and centrifuged within five minutes at <NUM> rpm and <NUM>. The plasma was separated and kept at -<NUM> until it was analysed for its nitrate and nitrite concentrations by a chemiluminescence assay as described previously (Lundberg <NUM>, supra).

Results are expressed as means +/- standard deviation (mean +/-SD). Paired t-tests were used to evaluate the difference between the nitrate and the placebo trials. The significance level was set as p=<<NUM>.

Gross efficiency (GE) was defined as the work rate divided by the actual energy expenditure (EE). The EE was in turn calculated with the Brouwer equation (BROUWER, E. On simple formulae for calculating the heat expenditure and the quantities of carbohydrate and fat oxidized in metabolism of men and animals, from gaseous exchange (<NPL>). Delta efficiency (DE) was defined as the increase in work rate divided by the increase in EE (<NPL>). The DE was based on the four lowest work rates and was analyzed with linear regression. The oxygen pulse is defined as VO<NUM>/HR.

Average resting systolic blood pressure was lower after nitrate supplementation (<NUM> +/- <NUM> mmHg) compared to placebo (<NUM> +/- <NUM>, p<<NUM>). The diastolic blood pressure was also lower after nitrate (<NUM> +/-<NUM> mmHg) compared to placebo (<NUM> +/- <NUM> mmHg, p<<NUM>). Parts of these findings have been published as a separate communication (Larsen et al.

No change was observed in [Hb] at rest (NIT <NUM> +/-<NUM>, CON <NUM> +/-<NUM> x l-<NUM>, p=<NUM>) or immediately after the VO2peak-test (NIT <NUM> +/- <NUM>, CON <NUM> +/-<NUM> x l-<NUM>, p=<NUM>). Nor were there any change in the hematocrit value at rest (NIT <NUM> +/-<NUM>, CON <NUM> +/-<NUM>%, p=<NUM>) or after the VO2peak-test (NIT <NUM> +/-<NUM>, CON <NUM> +/-<NUM>%, p=<NUM>).

Plasma levels of nitrate at rest were <NUM> +/- <NUM> in CON and <NUM> +/- <NUM> in NIT (p=<<NUM>). Nitrate levels immediately after the maximal work test were <NUM> +/-<NUM> in CON and <NUM> +/- <NUM> in NIT (p=<<NUM>). Plasma nitrate did not change during exercise either in NIT or in CON (p=<NUM>). Nitrite levels at rest were <NUM> +/- <NUM> in CON and <NUM> +/- <NUM> in NIT (p=<<NUM>). Immediately after the maximal work test the nitrite levels were <NUM> +/- <NUM> in CON and <NUM> +/- <NUM> in NIT (p=<NUM>). The decrease in nitrite concentrations during exercise was more pronounced in NIT than in CON (See <FIG>).

After nitrate administration VO<NUM> was significantly lower during the five work rates corresponding to <NUM>-<NUM>% VO2peak compared to the placebo period (<FIG>). The most significant difference was seen at <NUM>% of VO2peak (NIT <NUM> +/-<NUM> x min-<NUM> vs CON <NUM> +/-<NUM> x min-<NUM>, p=<NUM>, <FIG>). On average VO<NUM> was <NUM> x min-<NUM> lower in the NIT-trials over the five submaximal work rates. There was no difference in heart rate (HR) between the NIT and CON-trials (see <FIG>). The oxygen pulse tended to decrease from <NUM> +/- <NUM> during CON to <NUM> +/- <NUM> x beat -<NUM> (p=<NUM>). No differences were found between NIT and CON in [Hla] (<FIG>), VE, VE/VO2 or respiratory exchange ratio (RER) during any of the submaximal work rates. The average gross efficiency improved from <NUM>% during CON to <NUM>% during NIT (p=<NUM>). Delta efficiency (DE) increased significantly from <NUM> +/- <NUM> % during CON compared to <NUM> +/- <NUM> % during NIT, (p=<NUM>).

Claim 1:
The use of inorganic nitrate and/or nitrite in an edible composition comprising a source of inorganic nitrate and/or nitrite for non-therapeutically enhancing exercise performance of a human, said enhanced performance manifested as reduced oxygen consumption (VO<NUM>) for the same amount of work, wherein intake of the edible composition delivering a dose of <NUM> - <NUM> mmol inorganic nitrate/kg body weight of the human and/or <NUM>-<NUM>µmol inorganic nitrite/kg body weight of the human per <NUM>.