Water is the basic substance of all the metabolic processes in the human body. It enables the transportation of metabolites (required for growth and energy-production) by means of the circulation and exchange of nutrients and end products of the metabolism between organs and the external medium. The water balance is regulated by hormones and the presence of electrolytes, especially sodium and chloride on the cell exterior, and magnesium and potassium on the cell interior.
Water alone is capable of freely crossing the cellular membranes. Osmosis is defined as the passing of water from an area with a low concentration of solute to an area with a higher level of concentration. The final objective of this exchange of water is to balance out both solute concentrations. In the human being, the transfer of body liquids takes place to normalize extra-cellular liquids at approximately 300 mOsm (isotonicity).
An Osmole is defined as the Avogadro number of particles. Thus, one mole of glucose is also one osmole. If one mole of NaCl is completely disassociated, 2 osmoles of particles are produced: 1 osmole of Na+ and 1 osmole of Cl−. One milliosmole (mOsm) is 10−3 osmoles. The most common concentration units are: osmolarity, osmoles of solute particles per liter of solution and osmolality, osmoles of solute particles per kilogram of pure solvent. Actually, most solutes are not completely disassociated, and osmolality should be defined as:Osmolality=osmole/kg H2O=φn C where:                φ: The osmotic coefficient that determines the degree of disassociation        n: The number of particles into which the molecule may disassociate        C: The molal concentration of the solution One mOsm/kg is one mmole/kg in S.I. units.        
Apart from the solute concentration, blood pressure also plays a significant role in the exchange of liquids. Together with the osmotic effects, blood pressure determines the proportion in which water leaves the circulation to enter the tissues, or enters the blood flow from the tissues.
The daily intake of food normally supplies quantities of sodium, chloride and potassium that are much higher than an adult's minimum needs. However, the plasmatic levels of electrolytes may be affected in cases of substantial losses, such as acute diarrhoea or intense and prolonged perspiration. In these cases, the inclusion of electrolytes is advisable in rehydration solutions.
Fat is an important energetic substrate, but its oral intake can cause problems, since it is one of the powerful inhibitors of gastric emptying and its absorption process is slow. However, the medium chain triglycerides, or MCT, do not appear to inhibit gastric emptying at the same level as fats. The intake of MCT leads to an increase in fatty acids in plasma, which could lead to an increase in the oxidation of fats and a reduction in the use of carbohydrates, with a saving in muscular glycogen. Recent research indicates that drinks containing both MCT and maltodextrins produce faster gastric emptying than drinks that contain only maltodextrins.
Supplementing a diet with minerals and vitamins in the cases of healthy individuals who follow a well-balanced diet containing sufficient amounts of meat, fruit, vegetables, cereals and wholemeal products will, in general, not be beneficial. However, due to various factors, the diet of athletes subject to intensive training is often unbalanced. The intake of minerals depends largely on the selection of food and the quantitative amount consumed, from what it gives rise to circumstances in which a supplement is desirable, such as in any situation in which athletes wish to abstain from a normal diet, or during periods when food intake is limited due to intensive training, especially in women, in those taking part in weight sports and in vegetarian athletes, where the consumption of diets with low micronutrient levels has been observed. It is also recommendable to add mineral substances to products and food that are prepared and designed to replace normal food during hyper-resistance competitions, such as the triathlon, resistance competitions which last several days, and high mountain climbing. However, the levels should not surpass those recommended as being safe for daily intake.
Healthy people (including athletes) often have a low intake of iron, zinc, copper and chrome. These low intake levels can lead to low levels of micro-elements, which can be exacerbated by the losses in perspiration and urine brought about by physical exercise, as well as by the low contributions and the increase in the losses caused by the high consumption of carbohydrates by athletes, especially during resistance competitions.
The effects of almonds on people's health are manifold. On the one hand, their high content in essential nutrients (minerals, vitamins, amino acids and fatty acids) covers part of the daily requirements for these nutrients. The high content of oleic acid, mostly a fatty acid which enables a favourable proportion of monounsaturated and saturated fatty acids, as well as a moderate and balanced content in polyunsaturated fatty acids and high levels of vitamin E means their consumption is beneficial to health. All these effects give almonds a high nutritional and biological value, together with the fact that they are a high quality source for dietetic lipids and fibre. The nutritional composition of the almond has been known for some time, and is the subject of many publications and databases. Normally, the different bibliographical sources coincide on the composition of the almond; however, there are variations regarding the effect on their nutritional value when they are roasted. Generally speaking, it is considered that the almond is a food with a high energy level, proteins, fats, minerals and vitamins. Its arginine content is outstanding, an amino acid that appears to play an important role in the processes associated with the dynamics of the cardiovascular system. Furthermore, it is a nut that is rich in calcium, iron, magnesium, phosphorus, zinc and copper, as well as in vitamins, in particular vitamins E, B2, niacin and biotin. It also has a high percentage of essential fatty acids and fibre.
Almonds have a significant content of vitamin E, which is noteworthy due to its antioxidant character, thus avoiding the formation of free radicals which provoke mutation, distort the membrane phospholipids and damage their structure. Intense physical activity produces a situation of oxidative stress which can be compensated with an increase in the consumption of vitamin E, as we have shown in intervention studies supplementing the diet with a complex of vitamin E, vitamin C and beta-carotene. Almonds have a high content of monounsaturated fatty acids, mostly oleic acid. Oleic acid is considered beneficial when it substitutes saturated fats, due to its depressor effect on plasmatic cholesterol. The preparation of products based on the almond is widespread and includes almost all types of food, from sauces, sweets, soups, desserts, starters, aperitifs, etc. The oxidation of fats is one of the main processes of the deterioration of food, causing changes in aroma, flavour, taste, nutritional value, consistency and appearance. The oxidation reaction of unsaturated fatty acids is a chain reaction, influenced by free radicals, and one that may be started in many ways. Among them, the action of lipoxygenase, an enzyme found in raw almonds, which catalyses the formation of hyperoxides from polyunsaturated fatty acids and oxygen. The activity of this enzyme is the cause of the deterioration of fatty food such as the Majorcan sausage (Pons, Palou, Oliver, 1998, The Use of antibodies against lipoxygenase (EC 1.13.11.12) in food or ingredients, Patent 009800615/0) and its deactivation leads to a delay in the start of the oxidation process of fats. Neither the dynamics of this enzyme during the ripening of the almond nor its deactivation possibilities are known.
Almond milk is a product with a very ancient origin, a drink that is very traditional in the Balearic culture. The basic ingredients of the recipe are almonds, sugar and water, together with various aromatising agents. The following is a recipe from a book which dates from the beginning of the century, Valsecchi, P. “The Modern Distiller-Liquor Dealer”, Barcelona 1928. The name of the product is “Almond syrup or almond milk, perfected by Henry y Guivourt”. The composition, broken down into the ingredients used, is of 16 parts sweet almonds, 5 parts bitter almonds, 96 parts sugar, 1 part gum arabic, 8 parts double orange-flower water and 52 parts pure water.
The preparation is given as follows: “Take already peeled, dried almonds; crush them in a marble mortar with 20 parts sugar, then separate this paste into 6 or 8 parts so that, when they are crushed separately, the result is a very fine powder, which is then dissolved in 52 parts pure water; then it is sieved under high pressure. Add the rest of the sugar and the gum to the liquid, heat the mixture bain-marie, shaking it so that it dilutes well; sieve with a cloth and add the orange-flower water to the liquid obtained, stirring well to prevent the formation of an oily film. The addition of the gum is to stop the syrup from separating as it settles. This syrup will be sweeter and more nourishing depending on the gum used”.