Fish oils and plasma lipid and lipoprotein metabolism in humans: a critical review.

Essential fatty acids in growth and development

The seed of Cannabis sativa L. has been an important source of nutrition for thousands of years in Old World cultures. Non-drug varieties of Cannabis, commonly referred to as hemp, have not been studied extensively for their nutritional potential in recent years, nor has hempseed been utilized to any great extent by the industrial processes and food markets that have developed during the 20th century. Technically a nut, hempseed typically contains over 30% oil and about 25% protein, with considerable amounts of dietary fiber, vitamins and minerals. Hempseed oil is over 80% in polyunsaturated fatty acids (PUFAs), and is an exceptionally rich source of the two essential fatty acids (EFAs) linoleic acid (18:2 omega-6) and alpha-linolenic acid (18:3 omega-3). The omega-6 to omega-3 ratio (n6/n3) in hempseed oil is normally between 2:1 and 3:1, which is considered to be optimal for human health. In addition, the biological metabolites of the two EFAs, gamma-linolenic acid (18:3 omega-6; ‘GLA’) and stearidonic acid (18:4 omega-3; ‘SDA’), are also present in hempseed oil. The two main proteins in hempseed are edestin and albumin. Both of these high-quality storage proteins are easily digested and contain nutritionally significant amounts of all essential amino acids. In addition, hempseed has exceptionally high levels of the amino acid arginine. Hempseed has been used to treat various disorders for thousands of years in traditional oriental medicine. Recent clinical trials have identified hempseed oil as a functional food, and animal feeding studies demonstrate the long-standing utility of hempseed as an important food resource.

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Hempseed as a nutritional resource: an overview

Depletion of Omega-3 Fatty Acid Levels in Red Blood Cell Membranes of Depressive Patients

Omega-3 polyunsaturated fatty acid levels in the diet and in red blood cell membranes of depressed patients

A detailed study was made of the fatty acid composition of plasma triglycerides, free fatty acids, phospholipids, red cell total phospholipids, phosphatidylcholine and phosphatidylethanolamine in 32 normal males and 18 normal females. No sex differences could be detected. There were substantial differences in the compositions of the various fractions and long-chain polyunsaturated fatty acids were particularly important in the red cells.

Fatty acids in plasma and red cell membranes in normal humans

We have measured all the essential fatty acids (EFA) in plasma phospholipids in forty-one adults with atopic eczema and fifty normal controls. The major dietary n-6 EFA, linoleic acid, was significantly elevated, but all its metabolites, 18:3n-6, 20:3n-6, 20:4n-6, 22:4n-6, and 22:5n-6 were significantly reduced. The major dietary n-3 EFA, alpha-linolenic acid, was also elevated, though not significantly, while all its metabolites were also significantly reduced. These observations suggest that atopic eczema is associated not with any defect of EFA intake, but with abnormal metabolism, possibly involving the enzyme delta-6-desaturase. Treatment with oral evening primrose oil produced partial correction of the n-6 EFA abnormality, but had no effect on the n-3 EFAs.

Essential fatty acids in the plasma phospholipids of patients with atopic eczema.

The interrelations between linoleic acid (LA) metabolites and fish oil fatty acids were studied. Sprague-Dawley rats (200-220 g) were fed a fat-free semisynthetic diet supplemented with 10% (by weight) of different combinations of evening primrose oil (EPO), a rich source of LA and gamma-linolenic acid, and polepa (POL), a marine oil rich in eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. The combinations of supplement were as follows: 9% EPO-1% POL, 8% EPO-2% POL, 7% EPO-3% POL, 6% EPO-4% POL and 5% EPO-5% POL. After two weeks on the respective diets, the animals were killed, and the fatty acid compositions of liver and plasma phospholipids were examined. The results showed that animals fed higher proportions of POL consistently contained higher levels of dihomo-gamma-linolenic acid (DGLA) (p less than 0.05), a metabolite of LA and GLA, and lower levels of arachidonic acid (AA) (p less than 0.01), a metabolite of DGLA through delta-5-desaturation. Thus, an inverse relationship between AA/DGLA ratio and EPA levels was found to exist (r = -0.765 in plasma and -0.792 in liver). However, there was no such relationship between AA/DGLA ratio and DHA levels. This result suggested that EPA but not DHA in fish oil exerts an inhibitory effect on the conversion of DGLA to AA.

N. Morse

Papers

Fatty acids in plasma and red cell membranes in normal humans

Essential fatty acids in the plasma phospholipids of patients with atopic eczema.

The influence of dietary manipulation with n−3 and n−6 fatty acids on liver and plasma phospholipid fatty acids in rats

Plasma essential fatty acids in pure and mixed race American Indians on and off a diet exceptionally rich in salmon.