DHA

 

 

A comprehensive review of recent advances in nutrition LONDON, ENGLAND. 
The article covers a wide area from infant mortality to obesity. 
Among the highlights: A 1986 Consensus Conference concluded that the intake of calcium supplements by women does not prevent or cure osteoporosis; however, the Conference did report beneficial effects of 1.5 g/day of calcium combined with small doses of estrogens. 
There is evidence that olive oil is beneficial in preventing cardiovascular heart disease (CHD). An inverse relationship has also been found between the level of essential fatty acids, particularly linoleic acid, in adipose tissue and CHD; the level of saturated fatty acids, on the other hand, has been found to be directly proportional to the occurrence of CHD. 
There is now also good evidence that EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) found in fish oils may protect against CHD. In Japan, the incidence of CHD and cerebral thrombosis have been found to be inversely proportional to blood levels of EPA. 
These levels are generally ten times as high among Japanese as among Americans. Both West and East Germany and Czechoslovakia now include linoleic acid or essential fatty acids in their tables of RDA; the recommended daily intake is about 10 grams. - - A non-volatile anti-platelet factor has recently been isolated from garlic and synthesised. The compound is derived from allicin and has been named ajoene. Ajoene is an effective substitute for heparin during surgery. - - There is no convincing evidence that moderate consumption of alcohol reduces the risk of CHD. - - Food intolerances and allergies are receiving increased attention from medical researchers. A case of a child suffering from juvenile rheumatoid arthritis is described in detail. All symptoms disappeared when cow's milk was eliminated from the child's diet. Dairy foods and beef were found to cause depression, headaches, skin eruptions, and pain on urination in some patients. Symptoms disappeared when intake of milk products and beef was discontinued. Reintroduction of milk produced adverse effects within three hours and it took 24 hours for them to disappear.
Bender, A.E. Some recent advances in nutrition. Journal of the Royal Society of Health, Vol. 108, No. 6, December 1988, pp. 191-197

 

Docosahexaenoic acid (DHA) fights depression ROCKVILLE, MARYLAND.

Researchers at the National Institute of Alcohol Abuse and Alcoholism believe that the increasing rates of depression seen in North America over the last 100 years are due to a significant shift in the ratio of n-6 (arachidonic acid, linoleic acid) to n-3 (docosahexaenoic acid, linolenic acid) fatty acids in the diet.

The human race evolved on a diet having a ratio of about 1:1 of these acids; it is now estimated to be between 10:1 and 25:1.

Docosahexaenoic acid (DHA) is a main component of the synaptic membranes and a lack of it has been linked to depression.

Fish oils are a rich source of DHA and it can also be biosynthesized in the body from linolenic acid. The researchers speculate that the depressions which often accompany alcoholism, multiple sclerosis, and childbirth (postpartum depression) are all due to a lack of DHA and can be corrected by increasing the dietary intake of DHA or linolenic acid (flax seed oil). They also point out that depression and coronary heart disease are strongly associated and that a low intake of n-3 fatty acids has been linked to both. Hibbeln, Joseph R. and Salem, Norman. Dietary polyunsaturated fatty acids and depression: when cholesterol does not satisfy.

American Journal of Clinical Nutrition, Vol. 62, July 1995, pp. 1-9

 

Oils and fats in human nutrition ROME, ITALY.

An international group of experts sponsored by the Food and Agriculture Organization (FAO) and the World Health Organization (WHO) has released a comprehensive report covering the latest scientific findings regarding the role of fats and oils in human nutrition.

The report "Joint FAO/WHO Expert Consultation on Fats and Oils in Human Nutrition" provides recommendations regarding the type and amounts of fats and oils required in the daily diet. Among the recommendations are:

Dietary fats should supply between 15 and 35 per cent of total energy intake. Women of reproductive age should consume at least 20 per cent of their energy from fat. Sedentary individuals should limit their fat intake to 30 per cent of energy.

Infants should be fed breast milk. If that is not possible, then they should be fed a formula which contains the same amount and proportion of fatty acids found in breast milk. Essential fatty acids such as DHA are particularly important to ensure adequate brain development.

Saturated fatty acids should constitute less than 10 per cent of total energy intake and linoleic acid should provide between four and ten per cent of energy intake. The daily cholesterol intake should not exceed 300 mg.

A high intake of trans fatty acids is undesirable. Governments should not allow foods which contain appreciable amounts of trans fatty acids to be labelled as being low in saturated fat.

Foods which are high in unsaturated fatty acids should be adequately stabilized with tocopherol (vitamin E).

The ratio of linoleic to alpha-linolenic acid in the diet should be between 5:1 and 10:1.

The experts conclude that an adequate and appropriate intake of dietary fat is essential for health.

WHO and FAO joint consultation: fats and oils in human nutrition.

Nutrition Reviews, Vol. 53, No. 7, July 1995, pp. 202-05

 

Docosahexanoic acid helps brain development MILAN, ITALY.

Researchers at the University of Milan report that infants whose formula contains long-chain polyunsaturated fatty acids [especially docosahexanoic acid (DHA)] have better brain development than children who do not receive DHA in their formula.

The observation supports earlier findings that there is a direct correlation between the DHA concentration in the red blood cells of infants and their visual accuity. The researchers recommend that infants who are not breastfed be fed on a DHA-enriched formula. Breast milk already contains the fatty acids necessary for good brain development. Agostoni, Carlo, et al. Docosahexaenoic acid status and developmental quotient of healthy term infants.

The Lancet, Vol. 346, September 2, 1995, p. 638

 

Omega-3 fatty acids help protect against heart disease SAN FRANCISCO, CALIFORNIA.

Researchers at the Veterans Affairs Medical Center report that docosapentaenoic acid and docosahexaenoic acid (a main component of fish oil) provide significant protection against the development of coronary heart disease (CHD). Their study involved over 6,000 middle-aged men who had samples of their blood taken between 1973 and 1976. During the next seven years, 94 of these men had a heart attack or died suddenly due to heart disease. The 94 men were matched with 94 healthy men and the fatty acid profile of their blood samples compared.

The researchers found that the 94 men with heart disease tended to have a higher serum level of the saturated fatty acid palmitic acid and conclude that a high level of this acid increases the risk of CHD by 68 per cent. Palmitic acid is the main saturated fatty acid in most diets. This acid is known to cause an increase in both total cholesterol and low-density cholesterol levels; the researchers, however, found that the detrimental effect of a high intake of palmitic acid persisted even after allowing for its cholesterol-increasing effect.

The researchers also determined that men with a higher blood level of the omega-3 unsaturated fatty acids, docosapentaenoic acid and docosahexaenoic acid had an almost 50 per cent lower risk of developing heart disease than did men with lower levels. The researchers also found that men with CHD tended to have a higher serum level of omega-6 fatty acids derived from linoleic acid, but were unable to confirm previous reports that these acids are linked to an increased risk of CHD.

Simon, Joel A., et al. Serum fatty acids and the risk of coronary heart disease. American Journal of Epidemiology, Vol. 142, No. 5, September 1, 1995, pp. 469-76

 

Hyperactive children lack essential fatty acids WEST LAFAYETTE, INDIANA.

Children suffering from attention-deficit hyperactivity disorder (ADHD) are inattentive, impulsive, and hyperactive. Researchers at Purdue University now report that hyperactive children have lower levels of key fatty acids in their blood than do normal children.

Their experiment involved 53 boys aged 6 to 12 years of age who suffered from ADHD, but were otherwise healthy and 43 matched controls. Analyses showed that the boys with ADHD had significantly lower levels of arachidonic, eicosapentaenoic, and docosahexaenoic acids in their blood. The hyperactive children suffered more from symptoms associated with essential fatty acid deficiency (thirst, frequent urination, and dry hair and skin) and were also much more likely to have asthma and to have had many ear infections.

The researchers conclude that ADHD may be linked to a low intake of omega-3 fatty acids (linolenic, eicosapentaenoic, and docosahexaenoic acids) or a poorer ability to convert 18-carbon fatty acids to longer more highly unsaturated acids.

The researchers conclude that supplementation with the missing fatty acids may be a useful treatment for hyperactivity.

Stevens, Laura J., et al. Essential fatty acid metabolism in boys with attention-deficit hyperactivity disorder.

American Journal of Clinical Nutrition, Vol. 62, No. 4, October 1995, pp. 761-68

 

DHA (Docosahexaenoic acid), which is one of the most prevalent fats in the brain and eye.

 

Association of dietary factors and selected plasma variables with sex hormone--binding globulin in rural Chinese women

Jeffrey R Gates, Banoo Parpia, T Colin Campbell, and Chen Junshi

Sex hormone--binding globulin (SHBG) is an important regulator of plasma sex steroids as well as a sensitive indicator of insulin resistance. SHBG may be an important diagnostic measure of risk for pathologies associated with insulin resistance syndrome (IRS) such as non-insulin-dependent diabetes mellitus (NIDDM), obesity, hypertension, dyslipidemia, and atherosclerotic cardiovascular disease.

In women, SHBG is also implicated in diverse pathologies such as cancers of steroid-sensitive tissues and hirsutism. Data from an ongoing ecological study linking diet and health in rural China were analyzed to determine the relation of selected plasma variables and diet to plasma concentrations of SHBG. All data represent county mean values, pooled by age and sex, to assess the relation between biochemical and lifestyle characteristics and disease-specific mortality rates at the county level. The study sample consisted of 3250 Chinese women between the ages of 35 and 64 y living in 65 widely dispersed rural counties. Consumption patterns for 21 different food groups were derived from a food-frequency questionnaire and a 3-d dietary survey and subsequently compared. Correlation analyses of county mean values demonstrated a significant association between SHBG and insulin, testosterone, triacylglycerols, body mass index, age at menarche, and several foods. In regression analyses, after adjustments, the strongest predictors of SHBG concentrations were the dietary intakes of rice ( = 0.42, P < 0.01), fish ( = 0.34, P < 0.05), millet ( = -0.27, P < 0.01), and wheat ( = -0.34, P < 0.01). When insulin, testosterone, and triacylglycerols were added to the model only triacylglycerols ( = -0.26, P < 0.05) remained a significant independent predictor of SHBG. Additional analyses suggested that the consumption of green vegetables was modestly positively correlated with SHBG and negatively with insulin values.

Consumption of rice and fish in particular appeared to favorably influence the principle plasma variables associated with a reduction in the risk for IRS pathologies. Am J Clin Nutr 1996;63:22-31.

Keywords: Sex hormone--binding globulin, insulin, diet, China, fish, rice, wheat

 

Essential nutrients and immunologic functions

Darshan S Kelley and Adrianne Bendich

US Department of Agriculture

Agricultural Research Service

Pacific West Area

Western Human Nutrition Research Center

Presidio of San Francisco

Hoffmann-La Roche Inc

Paramus, NJ

Several indexes of immune response, including responses on delayed-type hypersensitivity skin tests, antibody production, lymphocyte proliferation, cytokine production, and numbers of the specific subgroups of white blood cells, are influenced by essential nutrient intake and may serve as functional tests for evaluating nutritional status. In certain segments of the population, such as elderly persons and smokers, activity of the immune indexes can be increased through dietary supplementation with micronutrients, and there may be a rationale to increase selected recommended dietary allowances for the general population. The activity of the immune system may also be enhanced with decreases in total fat intake or lessened with increase in total fat intake, particularly of the n-3 type. Research to date,

therefore, suggests that several dietary componenets, both essential and nonessential, can affect human immune response. The intake of these nutrients can be modulated to regulate the activity of the immune system.

Am J Clin Nutr 1996;63:994S-6S.

Key words: Vitamin C, vitamin E, -carotene, dietary fat, n-3 fatty acids, n-6 fatty acids, cell-mediated immunity

 

Fish oil supplementation inhibits the expression of major histocompatibility complex class II molecules and adhesion molecules on human monocytes

David A Hughes, Andrew C Pinder, Zoe Piper, Ian T Johnson, and Elizabeth K Lund

To test the hypothesis that fish oil supplementation can inhibit the expression of functionally associated molecules on the surface of human blood monocytes, we randomly assigned 12 healthy adults to receive either an n-3 polyunsaturated fatty acid--rich fish oil supplement for 21 d or to receive no supplement.

The percentage of monocytes expressing major histocompatibility complex (MHC) class II molecules (HLA-DR, -DP, and -DQ), intercellular adhesion molecule-1, and leukocyte-function-associated antigen-1, and the intensity of expression of each molecule were quantified before and after the study period. Monocytes were examined immediately after blood sampling and again after incubation in serum-free culture medium for 24 h in the presence of interferon- to up-regulate expression of MHC class II molecules by the monocytes. The intensity of expression of all the monocyte surface molecules examined was significantly reduced after fish oil supplementation (P < 0.025), although there was no change in the percentage of monocytes expressing each molecule.

After incubation with interferon-, there was a similar inhibition of surface molecule expression (with the exception of HLA-DQ) by monocytes from the fish oil--supplemented group, and there was a reduction in the percentage of monocytes expressing both HLA-DR and -DP molecules (P < 0.025). No significant changes were observed in the reference group. Dietary supplementation with fish oil can inhibit the expression of surface molecules involved in the function of human antigen-presenting cells, a potential mechanism by which n-3 fatty acids may suppress cell-mediated immune responses. Am J Clin Nutr 1996;63:267-72.

Keywords: Fish oil, n-3 fatty acids, humans, monocytes, MHC class II molecules, adhesion molecules

 

Effect of long-chain n-3 fatty acid supplementation on visual acuity and growth of preterm infants with and without bronchopulmonary dysplasia

Susan E Carlson, Susan H Werkman, and Elizabeth A Tolley

Departments of Pediatrics, Obstetrics and Gynecology, Biochemistry,

and Biostatistics and Epidemiology

The University of Tennessee

Memphis

Healthy preterm infants fed formula with long-chain n-3 fatty acids (n-3 LCFAs) from marine oil have better early visual acuity but lower plasma phosphatidylcholine (PC) arachidonic acid (AA) and growth than infants fed formula containing linolenic acid (LLA) as the sole n-3 fatty acid.

This randomized, double-blind trial was designed to study the effects of a different source of n-3 LCFAs and a shorter feeding interval on visual acuity (by Teller Acuity Card) and growth of preterm infants (n = 59; 747--1275 g birth wt), some of whom required long periods of supplemental oxygen and developed bronchopulmonary dysplasia (BPD). Infants were studied at 0, 2, 4, 6, 9, and 12 mo past term. Plasma PC AA, and normalized weight, length, and head circumference were not influenced by BPD or n-3 LCFAs except that n-3 LCFA-supplemented infants weighed less at 6 (P < 0.05) and 9 (P < 0.01) mo and had smaller head circumferences at 9 mo (P < 0.05). Compared with control infants, however, those fed n-3 LCFAs had lower weight-for-length at 2, 6, 9, and 12 mo (P < 0.0003, P < 0.0114, P < 0.0008, and P < 0.006, respectively). n-3 LCFAs improved early (2-mo) but not later acuity among infants without BPD (P < 0.02). Regardless of diet, infants with BPD had poorer grating acuity at 2 (P < 0.0002) and 4 (P < 0.04) mo but not thereafter Am J Clin Nutr 1996;63:687-97.

Key words: Linolenic acid, docosahexaenoic acid, eicosapentaenoic acid, arachidonic acid, preterm infants, visual acuity, growth, bronchopulmonary dysplasia

 

Effect of n-3 polyunsaturated fatty acid intake on phospholipid fatty acid composition in plasma and erythrocytes

Domenico Prisco, Monica Filippini, Isa Francalanci, Rita Paniccia, Gian Franco Gensini, Rosanna Abbate, and Gian Gastone Neri Serneri

Istituto di Clinica Medica Generale e Cardiologia

University of Florence

Italy

To characterize the time course of plasma and red blood cell (RBC) changes after n-3 polyunsaturated fatty acid (PUFA) supplementation, 20 healthy male volunteers were randomly assigned to receive either four 1-g capsules of n-3 PUFA ethyl esters or four 1-g capsules of olive oil (as placebo) for a period of 4 mo, followed by a 3-mo washout period. Fatty acids of plasma and RBC phospholipid fractions were analyzed at 0, 2, and 4 mo of treatment and at 1, 2, and 3 mo of washout. During n-3 PUFA supplementation, accumulations of eicosapentaenoic (EPA), docosapentaenoic (DPA), and docosahexaenoic (DHA) acids were marked after 2 mo with differences among different fractions of plasma and RBCs in further accumulation up to 4 mo.

During the first and second months of the washout, slight differences were observed in changes of various fatty acids among different phospholipid fractions, but after 3 mo of washout, only minor alterations were still detectable with respect to pretreatment values.

These data confirm the complex relations among different fatty acid pools after n-3 PUFA supplementation.

Am J Clin Nutr 1996;63:925-32.

Key words: n-3 Polyunsaturated fatty acids, eicosapentaenoic acid, docosahexaenoic acid, plasma, red blood cells

 

Immunologic effects of marine- and plant-derived n-3 polyunsaturated fatty acids in nonhuman primates

Dayong Wu, Simin Nikbin Meydani, Mohsen Meydani, Michael G Hayek, Peter Huth, and Robert J Nicolosi

The effect of marine- and plant-derived n-3 polyunsaturated fatty acids (PUFAs) on T cell--mediated immune response was studied in cynomolgus monkeys. Animals were first fed a 14-wk baseline diet; 10 animals were then fed diets containing 1.3% or 3.3% of energy as eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA) while the other 10 were fed diets containing 3.5% or 5.3% of energy as -linolenic acid (ALA) for two consecutive 14-wk periods.

Both diets significantly decreased the percentage of T cells (except 1.3% EPA + DHA), T helper cells (except 1.3% EPA + DHA and 3.5% ALA), and T suppressor cells. Proliferative response of lymphocytes to T cell mitogens significantly increased after the diet containing 3.3% EPA + DHA. Interleukin 2 production significantly increased after the diets containing 1.3% and 3.3% EPA + DHA. No significant changes in mitogenic response or interleukin 2 production were found after ALA diets. Feeding 1.3% or 3.3% EPA + DHA or 5.3% ALA significantly suppressed prostaglandin E2 production in response to T cell mitogens. Plasma tocopherol concentrations were decreased significantly only in monkeys fed ALA diets.

We conclude that after adjustment for the tocopherol concentration, marine-derived n-3 PUFAs but not plant-derived n-3 PUFAs increased T cell--mediated mitogenic response and interleukin 2 production. This is most likely due to diet-induced quantitative differences in cellular fatty acid composition and, thus, in prostaglandin E2 production and tocopherol status.

Am J Clin Nutr 1996;63:273-80.

Key words: Nonhuman primates, n-3 polyunsaturated fatty acids, PUFAs, eicosapentaenoic acid, EPA, docosahexaenoic acid, DHA, -linolenic acid, ALA, immune response