Essential fatty acid measurements

In addition, many different psychiatric conditions such as schizophrenia, depression and post-traumatic stress syndrome have been associated with changes in the essential fatty acid levels that can easily be measured in erythrocytes or plasma [2, 3]. 

Long-chain fatty acids are hydrophobic substances in plasma they occur in the esterified state or bound to protein (mainly albumin). As a consequence, long-chain fatty acids are not excreted into the urine and are measured either in the plasma or in erythrocytes, where they are part of the membrane. Erythrocyte levels of polyunsaturated fatty acids (PUFA) are fairly constant and may reliably reflect the longterm availability or deficiency of the essential fatty acids. A list of fatty acids that can be separated and analysed by GC is shown in Table 3.3.1. 

Dietary fat is also important as a source of the fat-soluble vitamins, A, D, E, and K. Requirements for the fat-soluble vitamins are several orders of magnitude lower than that of the essential fatty acids, being measured in micrograms rather than grams per day. Since the fat-soluble vitamins are required for growth and development, much interest has been focused on the concentration and availability of these vitamins in human milk. 

Similar reversals of biochemical deficiencies of n-3 fatty acids or of total essential fatty acids have been studied in the rodent brain under somewhat different experimental conditions (Walker, 1967, Sanders etal., 1984, Youyou etal., 1986, Homo mayoun etal., 1988, Leyton et al., 1987). In the experiments by Youyou et al., complete recovery from the n-3 fatty acid deficiency, as measured by an increase of DHA and a decrease of 22 5n-6, required 13 wk as compared to 6-12 wk in our monkeys. There were major differences between this study and ours, which may be responsible for the different recovery rates observed. Most importantly, we fed monkeys fish oil, which is high in... 

A comprehensive nutrition assessment must include an evaluation of possible trace element, vitamin, and essential fatty acid deficiencies. Because of their key role in metabolic processes (as coenzymes and cofactors), a deficiency of any of these nutrients may result in altered metabolism and cell dysfunction, and may interfere with metabolic processes necessary for nutritional repletion. The evaluation of single-nutrient-deficiency states includes an accurate history to identify symptoms and risk factors that may indicate deficiency or predispose the patient to developing a deficiency state. A focused physical examination for signs of deficiencies and biochemical assessment to confirm a suspected diagnosis also should be done. Ideally, biochemical assessment would be based on the nutrient s function (e.g., metalloenzyme activity) rather than simply measuring the nutrient s serum concentration. Unfortunately, few practical methods to assess micronutrient function are available currently, and most assays measure serum concentrations of the individual nutrient. 

Lipids. Fasting plasma triglyceride levels provide some indication of fat metabolism, but arc again affected by a variety of metabolic priKcsscs. Essential fatty acid levels may be measured if specific deficiencies are suspected. Faecal fat may be measured both qualitatively and quantitatively in the assessment of malabsorption (pp. 104-105). 

The requirement of adequate amounts of endogenous prostaglandin precursors may explain why certain of these acids are essential to the diet [73, 87, 89]. The essential fatty acid (E.F.A.) activity of a series of acids, as measured by the ability of their methyl esters to produce a change in weight in E.F.A. deficient rats, has been shown to correlate approximately with their conversion rates into prostaglandins. Only those fatty adds which yielded biologically active prostaglandins showed considerable activity [89]. 

Ten Hoor and co-workers (1973) measured heart function In rats during maximum lipidosis, i.e., 3 days after feeding a HEAR oil containing diet. Heart function was measured two ways, one, in isolated left ventricular papillary muscle and the other with a heart-lung preparation in which the work load put on the heart could be adjusted as desired. With all measured parameters (i.e., maximal isometric contractile force, maximal developed tension and rate of tension development, and left ventricular stroke work), the hearts from rats that were put on a 50 calorie % HEAR oil diet had poorer contractile properties than did the hearts from the control group that received sunflower oil. Similarly, when rats were reared on an essential fatty acid deficient diet, the contractile force of isolated papillary muscle from heart was weaker than that from the control group that received linoleic acid, I.e., sunflower oil supplement. These authors suggest that in both instances the decreased contractile force of heart muscle may be related to an Impaired mitochondrial function and a decreased rate of ATP synthesis. 

Eggs provide a unique source of balanced nutrients, including protein, essential fatty acids, vitamins, and minerals. The protein is of such high value that it is used as a standard to measure the quality of other food proteins. 

In an attempt to examine some properties of cancer cells we have measured the ability of Novikoff hepatoma to take up the saturated and "essential fatty acids" from the host and the capacity of this tumoral tissue to distribute these acids between the different lipid fractions. pH -glycerol was also used as a marker for "de novo" glycerolipid biosynthesis. 

Hansen and his co-workers undertook a long term massive study of essential fatty acid phenomena in infants. In a clinical study of 428 infants, who were fed with five different dietary formulae, they found differences in the dienes, trienes, tetraenes, pentaenes and hexaenes measured by alkaline isomerization. They also found that the content of linoleic acid in the proprietary formulae varied... 

Diabetic animals develop signs of essential fatty acid deficiency earlier than normal ones on a diet deficient in essential fatty acids (Peifer and Holman, 1955). In the diabetic a reverse relation is present between the essential fatty acid content of the blood and the glucose level. Furthermore, it is well known that diabetics develop atherosclerosis easily, while diabetic women are known to suffer frequently from toxemia of pregnancy also. The prevalence of both diseases in diabetics might be related to the endocrine disorder itself but could equally well be due to the dietary measures. Especially the low carbohydrate-high fat diet, formerly so commonly described, must be considered as harmful in this respect. Even the resistance to radiation sickness is less in essential fatty acid deficiency states (Decker et al., 1950 Cheng et al., 1954, 1955, 1956 Deuel et al., 1953). 

The measurements of the total amount of various essential fatty acids as co-3 fatty acids in plasma, serum, or erythrocyte membrane phospholipids have been indicated as useful markers of essential polyunsaturated fatty adds. Essential fatty acid deficiency is a clinical condition that derives from inadequate status of co-3 and co-6 fatty acids however, the symptoms are nonspecific and may not present prior to marginal essential fatty acid status. Widely used biomarkers for bicx hemi( essai-tial fatty acid deficiency are mead acid and the triene/tetraene ratio. Howcvct, the total plasma triene/tetraene ratio has been considered the gold standard for essential fatty acid deficiency. Mead acid, or 5,8,11-eicosatrienoic acid (5,8,11-20 3 co-9) is synthesized from endogenous oleic acid and is increased when there is insufficient concentrations of linoleic and a-linolenic acid to meet the needs of polyunsaturated fatty acids. Under normal conditions only trace amounts of mead acid are found in plasma. EPA and DHA inhibit mead acid synthesis. Mead acid measurement is an indicator of essential fatty acid deficiency state, while essential fatty add depletion is associated with a decrease in plasma hnoleate and arachidonate percentages. Assessment of long-term essential fatty acid intake is measured in adipose tissue, and it is considered the best indicator because of its slow tumover. - Cutoff values for the assessment of essential fatty adds and to-3 fatty acid status in erythrocytes have been reported. Proposed cutoff values for children older than 0.2 years are 0.46 mol% 20 3 co-9 (mead acid) for early suspicion of essential fatty acid defidency, 0.068 mol/mol docosapentaenoic/arachidonic acid... 

Holman, R.T., The ratio of trienoic tetranoic acids in tissue lipids as a measure of essential fatty acid requirement, J. Nutr., 70, 405-410, 1960. 

It is well known that LA prevents abnormal water loss through the skin, which occurs in cases of essential fatty acid deficiency. However, ALA was not effective at reducing excessive water loss in rats (Hansen and Jensen, 1985). A case report on three elderly people revealed that a low ALA intake was associated with dry, scaly and atrophic skin (Bjerve, 1987), although there was no measurement of water loss in these subjects. In rhesus monkeys, ALA deficiency is associated with increased water intake, balanced by increased... 

Several aspects of eicosanoid metabolism and function, however, need urgent research. These include (a) the mechanism by which the relative proportions of the different eicosanoids are regulated (b) the significance of changes of dietary fatty acid composition for whole body eicosanoid production (c) the quantitative significance of the different pathways and sites of synthesis and (d) the quantitative relationships between the requirements for essential fatty acids, which are measured in grams and the daily production of eicosanoids, which is measured in micrograms. 

Human requirements for the essential fatty acids are measured in grams per day those for the fat soluble vitamins, in micrograms per day. It was realized early this century that minute amounts of substances other than proteins. 

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