Food sources and health benefits of ω-3 fatty acids – DHA and EPA

N-3 fatty acids are essential for normal growth and development and may play an important role in the prevention and treatment of coronary artery disease, hypertension, diabetes, arthritis, other inflammatory and autoimmune disorders, and cancer. The multiple actions of n-3 fatty acids appear to involve multiple mechanisms that connect the cell membrane, the cytosol, and the nucleus.

α-linolenic acid (ALA) is the major n-3 fatty acid. α-linolenic acid cannot be synthesized in humans and is an essential dietary fatty acid. In the body, α-linolenic acid is metabolized to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

Linseeds (flaxseeds) and their oil typically contain 45–55% of fatty acids as a-linolenic acid, whereas soybean oil, rapeseed oil, and walnuts all typically contain ~10% of fatty acids as a-linolenic acid.

The omega-3 (n-3) fatty acids, eicosapentaenoic acid (EPA; 20:5 n-3) and docosahexaenoic acid (DHA; 22:6 n-3), are found in seafood (especially fatty fish), supplements and concentrated pharmaceutical preparations.

The blubber and tissues of sea mammals, such as whales and seals, also contain EPA and DHA in significant amounts.

In addition to providing people with high-quality proteins, fish consumption satisfies nutritional requirements for essential n-3 fatty acids, primarily eicosapentaenoic (EPA; 20:5 n-3) and docosahexaenoic (DHA; 22:6 n-3) acids, which are two long chain polyunsaturated fatty acids (LC-PUFAs) mainly present in fish.

Docosapentaenoic acid (DPA) (22:5n-3), a long-chain n-3 PUFA metabolite of EPA, is also present in smaller amounts in fish.

Fish oil is obtained from oily fish flesh or lean fish livers (e.g., cod liver). Fish oil is rich in very long-chain (n-3) fatty acids and in a typical fish oil, EPA and DHA comprise ;30% of the fatty acids present.

EPA and DHA are essential for proper fetal development and healthy aging. EPA emerging as a new potential agent in the treatment of depression. EPA can reduce symptoms of depression and help fight inflammation in human body.

DHA is essential for normal fetal brain and cognitive development as the formation of neuron synapses in the brain depends strongly on the integration of this fatty acid into growing neurons. DHA is a key component of all cell membranes and is found in abundance in the brain and retina.

Increasing n-3 fatty acids intake significantly reduces the incidence of cardiovascular disease. They reduce total cholesterol, and thus minimize significantly the risk of myocardial infarction.

The potential for EPA and DHA to have a role in reducing the risk of cardiovascular disease was first identified by studies in the Greenland Inuit, where the low rate of mortality from myocardial infarction and ischaemic heart disease.

Food sources and health benefits of ω-3 fatty acids – DHA and EPA

Catabolism of fatty acids

Catabolic pathways ware characteristically energy yielding, whereas anabolic pathways are energy requiring. Catabolism involves the oxidative degradation of complex nutrient molecules obtained either from the environment or from cellular reserves.

 Fatty acids are released from triglycerides stories in adipose tissue, transported in plasma in association with albumin and delivered to cells for metabolism. The fatty acids are catabolised by β-oxidation. The products of catabolism of phenyl derivatives of benzoic acid or phenylacetic acid, or their higher homologs, are excreted in urine. These products are always the derivatives of benzoic acid or phenylacetic acid.

In the fatty acid catabolism, two carbon units are sequentially removed, beginning from the carboxyl-terminal end. The major end products are acetyl co enzymes A and the reduced forms of the nucleotides FADH2 an NADH.
Catabolism of fatty acids

Monounsaturated fatty acids

Monounsaturated fatty acids are a fatty acid containing one point of unsaturation.

Plant sources that are rich in monounsaturated fatty acids include vegetables oils that are liquid at room temperature (eg, canola oil, olive oil, high oleic safflower and sunflower oil) and nuts.

When monounsaturated fat such as olive replaces started and trans fats in the diet, the risk of heart disease may be lessened.

Monounsaturated fat as in seafood, nuts, olive oil, canola and coconut oil, are considered the healthiest fats.

They are rich with fatty acids and important for normalizing prostaglandin levels. Studies suggest that deist rich in monounsaturated fats might be of benefits, especially for diabetes with insulin resistant.

A diet higher in monounsaturated fatty acid appeared to provide an advantage over a fiber-rich, high carbohydrates, low-fat diet on body fat distribution among diabetics.
Monounsaturated fatty acids

Classification of Lipids

Classification of Lipids
Lipids include all substances that are extractable from biological materials with the usual fat solvents (ether, chloroform, benzene, carbon tetrachloride, acetone, etc). Certain lipids are an energy source for the cell, others are structural compounds (particularly important are the lipid constituents of cell and organelle membranes), and still other function as hormones. This diversity of function recalls the not too remote past when lipids were considered to be inert constituents of adipose cells.

Of the many compounds classified as lipids, only fraction is significant in the diet, or in the structure and function of the human cell. The following classification is limited to lipids of importance in animal nutrition and excludes the fat soluble vitamins that, although properly classified as lipids, following the classic practice of nutritionist.

A. Simple Lipids
Fatty acids
Neutral fats (mono-, di- and triacyl glycerols)
Wax
*Sterol ester
*Nonsterol ester

B. Compound Lipids
Phospholipids
*Phosphatidic acids, lecithin, cephalins, etc
*Plasmalogens
*Sphinghomyelins
Glycolipid (carbohydrate containing)
Lipoproteins (lipids in combination with protein)

C. Derived Lipids, alcohol (including sterols and hydrocarbons)
Classification of Lipids