Conditionally essential fatty acids

Fatty acids, such as linoleic, hnolenic, and arachidonic acids, contain two or more cis carbon-carbon double bonds and are referred to as polyunsaturated fatty acids. Several of these fatty acids, including linoleic and linolenic acids, are required nutrients for humans and must be part of a healthy diet. They are termed essential fatty acids, of which there are eight. These fatty acids cannot be synthesized by human beings but are essential to human health. Therefore, they must be consumed in adequate amounts in a healthy diet, specifically in the form of ingested plant-derived foods. A diet devoid of the essential fatty acids eventually results in a fatal condition characterized by inflammation of the skin (dermatitis), failure of wounds to heal, and poor growth. The essential fatty acids serve as precursors for complex molecules termed eicosanoids, to which we return below. 

A functional method for detection depends upon competition for the activity of the and desaturases between a non-essential fatty acid (e.g. oleic acid) and an essential fatty acid (see above). If the latter is deficient, oleic acid is readily converted, via the desaturases, to Mead acid, since there is little competition (Figure 11.14). Hence the amount of the latter can be used as a marker for deficiency of essential fatty acids, although it is better to use the ratio of double bonds only three are present in Mead acid (i.e. a triene) but four are present in arachidonic acid (i.e. a tetraene). A ratio in plasma, triene/tetraene >4.0 is an indication of a deficiency of essential fatty acids. This method has shown that a deficiency can occur in a number of conditions which can lead to disease (Table 11.5). 

Table 11.5 Conditions in which a deficiency of essential fatty acids can occur...

The diversity of size and form of babies bom even after normal pregnancy is remarkable. However, this is not only due to genetic variation but to the behaviour and nutrition of the mother adequate nutrition, macro- plus micronutrients, plus the essential fatty acids, essential amino acids and the conditionally essential amino acids. Too high an intake of alcohol and smoking tobacco are known to affect the size of the baby with, in some cases, a reduction in the nnmber of cells in particular tissues/organs. 

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]. 

Fish oil has been one of the hottest topics in general nutrition and health care over the past few years, mainly because it is primarily composed of - fatty acids. The benefits of fish oil have a strong foundation in well-documented scientific studies, the most important ones dealing with the treatment of heart disease. Treatment of any condition associated with essential fatty acid changes inevitably involves the use of fish oil or more specific mixtures of the primary important essential fatty acids [14]. 

Skin diseases including essential fatty acid deficiency and ichthyosis may also affect the transdermal delivery of a compound. Studies have shown that the epidermal barrier function is altered by abnormal lipid composition in noneczematous atopic dry skin. Numerous other dermatologic conditions affect the anatomical structure and function of skin, which may impact on the nature of the toxic responses seen. 

Edible fats and oils (lipids) are derived from plant, animal, and marine sources. Fats and oils differ in that fats are solids at normal room temperature whereas oils are liquids under similar conditions. Lipids are recognized as essential nutrients in both human and animal diets. They provide the most concentrated source of energy of any foods. The caloric value of lipids (9 kcal/g) exceeds twice that of proteins and carbohydrates (4 kcal/g). Lipids not only contribute to flavor, color, odor, and texture of foods, but also confer a feeling of satiety after eating. Lipids also act as carriers of fat-soluble vitamins, supply essential fatty acids, and increase the palatability of foods. Dietary fats are often categorized as visible or invisible ... 

Today, the oil is used medicinally to treat a myriad of conditions related to essential fatty acid (EFA) deficiencies, low dietary intake of linoleic acid, and a variety of reproductive, cardiovascular, inflammatory, and neurological disorders. It is added to foods as a source of essential fatty acids and used in topical products such as soaps and cosmetics (5-7). 

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... 

Symptoms of essential fatty acid deficiency may include fatigue, skin problems, immune weakness, gastrointestinal disorders, heart and circulatory problems, growth retardation, and sterility (Belzung et al., 1998). In addition to these symptom conditions, a lack of dietary essential fatty acids has been implicated in the development or aggravation of breast cancer, prostate cancer, rheumatoid arthritis, asthma, preeclampsia, depression, schizophrenia, and ADHD (attention-deficit/hyperactivity disorder). The list is neither exhaustive nor conclusive. 

CAA crystalline amino acid CEAA conditionally essential amino acid CPN central parenteral nutrition CSP compounded sterile preparations EFAD essential fatty acid deficiency... 

In addition to supplying us with fuel and with general-purpose building blocks for biosynthesis, our diet also provides us with specific nutrients that we need to remain healthy. We must have a regular supply of vitamins and minerals and of the essential fatty acids and essential amino acids. Essential means that they are essential in the diet the body cannot synthesize these compounds from other molecules and therefore must obtain them from the diet. Nutrients that the body requires in the diet only under certain conditions are called conditionally essential. ... 

Cunnane, S.C. (2000) The Conditional Nature of the Dietary Needs for Polyunsaturates a Proposal to Reclassify Essential Fatty Acids as Conditionally-Indispensable or Condition-ally-Dispensable Fatty Acids, Br. J. Nutr. 84,803-812. 

Cunnane, S.C. (19%) Recent Studies on the Synthesis, Beta-Oxidation and Deficiency of Linoleate and y-Linolenate Are Essential Fatty Acids More Aptly Named Indispensable or Conditionally Dispensable Fatty Acids Can. J. Physiol. Pharmacol. 74, 629%39. 

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