Carbohydrate upper level

For adults, based on the Acceptable Macronutrient Distribution Range, the lOM recommmds a range of 20 to 35% of total calorie intake to be ingested as fat. Low intake of fats may increase the risk of inadequate intakes of essential fatty acids such as linoleic add and a-linolenic acid, and vitamin E. In addition, low-dietary-fat intake may have a potmtial adverse affect on lipid profiles due to increased carbohydrate intake often assodated with low-fat diets. Therefore, the NCEP reconunends a lower limit of 25% for individuals with elevated plasma cholesterol concentrations, established cardiovascular disease, and more than one major risk factor. On the other hand, an upper level intake of total fat, i.e., approximately 35% of total calories, is assodated with increased calorie and saturated fat intake. In individuals with lipid or metabofic disorders, total fat intakes should not be extreme... 

Biotin forms part of several enzyme systems and is necessary for normal growth and body function. Biotin functions as a cofactor for enzymes involved in carbon dioxide fixation and transfer. These reactions are important in the metaboHsm of carbohydrates, fats, and proteins, as well as promotion of the synthesis and formation of nicotinic acid, fatty acids, glycogen, and amino acids (5—7). Biotin is absorbed unchanged in the upper part of the small intestine and distributed to all tissues. Highest concentrations are found in the Hver and kidneys. Little information is available on the transport and storage of biotin in humans or animals. A biotin level in urine of approximately 160 nmol/24 h or 70 nmol/L, and a circulating level in blood, plasma, or serum of approximately 1500 pmol/L seems to indicate an adequate supply of biotin for humans. However, reported levels for biotin in the blood and urine vary widely and are not a reHable indicator of nutritional status. 

The type of root system developed by a plant depends not only on soil tilth but also on the level of nutrients present. The root system tends to be more branched and more concentrated in a fertile soil than in a poor one. If a poor soil is fertilized with well-rotted manure, for example, each pocket of manure will be filled with a mass of much-branched roots, whereas the remainder of the soil will have few roots other than the larger primary and secondary ones. Undoubtedly this extreme development of fine roots in manure is a response to chelated minor elements as well as to the major nutrients. If a poor soil is not fertilized with either chemical fertilizers of manure the top—root ratio is likely to be unusually narrow, and the roots may extend to deeper depths (Oswalt et al., 1959). We sometimes say that such roots are long because they are searching for nutrients, but the real explanation is that the carbohydrate level in the root increases as the available nutrient supply decreases. When the nutrients are inadequate for a luxuriant top growth there is a bigger excess of carbohydrates that are transported downward and used for root growth. Inadequate soil moisture in the upper part of the soil profile may also result in a deeper root system. 

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