Minimum nutrient requirements

Estimation of the linoleate requirement from the shapes of the individual curves has been accomplished (Caster et aJ., 1962). The value for half maximum change, I,, can be derived and the minimum nutrient requirement (MNR) calculated. MNR is equivalent to 70% of maximum change. These values are indicated for the three curves in Figure 6. The values deduced for trienes and tetraenes relate closely to metabolic parameters and lie below 2% of calories. The value deduced from dienes probably is related to deposition of linoleate and is a much higher value. 

RDA values are overestimates of nutrient requirements minimum quantities of nutrients required to maintain normal function and health in humans are either unknown or incompletely known. 

The most satisfactory way of determining the daily requirement of a particular nutrient is to devise a diet which is complete except for the nutrient being studied and to feed it to healthy volunteers together with graded supplements of the nutrient in question. The supplement which just finis to produce clinical change when fed over a period of some weeks represents the minimum daily requirement, lliis is easily done with animals, provided a suitable diet can be devised, but there are problems when using humans for this type of study because it may be necessary to take the diet for many weeks or months before clinical signs of a deficiency occur. 

At one time, a system of MDR (minimum daily requirement) values for nutrients was used. Why do you think Daily Values (DV) might be more informative and useful than MDRs ... 

Other approaches have been used to estimate nutrient requirements, such as metabolic balance studies and nutrient analysis of human milk. However, both of these approaches adopt an arbitrary target value to assess response to various nutrient intakes. For the premature infant, whose actual existence outside the womb is unnatural , it is impossible, other than by arbitrary definition, to define and justify goals. Therefore, although the intrauterine accretion data are based on relatively few observations and may be an underestimate of true intrauterine accretion, they presently represent the most appropriate guideline for establishing minimum growth and nutrient accretion goals in the newborn premature infant. 

The minimum manganese requirement of birds for the prevention of any of the above symptoms of deficiency depends upon three principal factors. These are (1) the breed, or even strain, of bird, (2) the quantity of calcium, phosphorus, and iron in the diet, and (3) the source, i.e., the form, of manganese supplied. The incidence of perosis may also be influenced by the level in the diet of several organic nutrients, of which choline and inositoU appear the most important. This aspect of perosis has been well reviewed by Jukes to 1941. 

Requirements—Nutrient requirements are the amount of nutrients necessary to meet an individual s minimum needs, without margins of safety, for maintenance, growth, pregnancy, and lactation. To meet nutrient requirements, individuals must receive sufficient food to furnish the necessary quantity of energy, protein, minerals, and vitamins. However, good nutrition is more than just meeting minimal needs. 

For the routine cultivation of bacteria, a cheap source of all likely nutrients is desirable, and it should also be remembered that even bacteria whose minimum requirements are veiy simple grow far better on more highly nutritious media. 

For limiting nutrients, cellular concentrations are constant under conditions of steady-state growth. To ensure that the limiting nutrient is not diluted in the microbial population, kmt must be greater than the maximal growth rate, /imax. This limiting condition sets a minimum for the value of the Monod constant, Kmd = / max /[7]- Note that while Monod kinetics are more applicable than first-order kinetics for many ecological uptake processes, solutions of the above equations require considerably more a priori information [48]. 

Soy Protein Concentrates. Both non-functional (low or no solubility) and functional (good solubility, emulsification capacity, and dispersibility) soy protein concentrates (70% protein, dry basis) are commercially available for use in meat products (2-4, 6, j), 15) Normally, a highly functional product with no harsh or bitter flavors is desirable. When used to replace lean meat, non-hydrated concentrate can be used at levels up to 6-7% in finished nonspecific emulsion meats Higher replacement levels or formulas with specific cost/nutrition requirements may use soy protein concentrate with a judicious amount of textured soy protein (6). Excellent yields, cost savings, texture, flavor and nutrient profiles are possible. However, most soy protein concentrates lack sufficient solubility or sufficiently low viscosities to be used in brines for absorption or injection into whole muscle tissue. When legal standards for protein content exist (13), more concentrate must be used to achieve legal minimums. Brine viscosities increase and uniform distribution of brine components throughout the specific whole muscle piece is restricted. Finished product appearance and flavor are easily compromised. Thus, use of soy protein concentrates in whole muscle applications is limited. 

Subjects who are maintained for prolonged periods by total parenteral nutrition are obviously wholly dependent on what is provided in the nutrient mixture, normally with no contribution from intestinal bacteria. A great deal has been learned from such patients, including the essentiality of the amino acid histidine, and evidence that endogenous synthesis of taurine (Section 14.5.3) and carnitine (Section 14.1.2) may not be adequate to meet requirements without some dietary provision. However, for obvious ethical reasons, such patients have not been subjected to trials of graded intakes of vitamins, but are generally provided with amounts calculated to be adequate and in excess of minimum requirements. 

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