Omega 3 fatty acids in the elderly

Population ageing affects the entire world population. Also at world level one can observe a sharp increase in the proportion of older people. The challenge posed by population ageing translates into ensuring that the extra years of life will be as good as possible, free from high-cost dependency. Omega-3 fatty acids are now generally recognized as potential key nutrients to prevent the pathological conditions associated to the aging process. Ageing physiological process, its association with quality of life and the impact of omega-3 fatty acids intake and/or status is the focus of the present review. This report deals with the effects of omega-3 fatty acids on normal aging of older adults ( ≥ 65 years) mainly on the effects such as nutritional status itself, cognition, bone health, muscle tonus, and general health status. The preliminary broad search of the literature on the effects of omega-3 fatty acids on normal aging yielded 685 citations. Forty two full text papers were checked for inclusion and thirty six studies were finally included in this review. It may be concluded that paradoxically even though the elderly population is the largest one, the number of studies and the methodology employed clearly lacks of sufficient evidence to establish definite conclusions on the effects of omega-3 fatty acids on aging metabolism without pathological conditions and on quality of life.     

Omega 3 fatty acids: biological activity and effects on human health

Polyunsaturated fatty acids (PUFAs) have an important role in human diet, both for the prevention and the therapy of different pathologies. In this review, a critical evaluation of PUFAs dietary sources and biological functions in human organism has been done. In particular, the efficacy of omega-3 fatty acids in the improvement of the lipidic pattern and in the excitability of myocardium has been analyzed, and, therefore, their usefulness in the prevention of cardiovascular diseases and postinfarction arrhythmias. As PUFAs are precursors of prostaglandins and leucotriens, which are involved in phlogosis and immune response, a diet rich in fish oil reduces the production of PGE2 involved in many phlogosis events. Moreover, an increase in the eicosapentaenoic acid (EPA) intake leads to a reduction in the production of inflammatory cytokines (interleukin 1, 2, 6 and tumor necrosis factor); so, it is important to use omega-3 in chronic inflammatory diseases, as the rheumatoid arthritis. It seems that omega-3 could prevent the onset of hormone-dependent tumours (i.e. breast and prostatic cancer); in vitro observations, in fact, have shown that the PG of the series 2, derived from omega-6, have a carcinogenic action; instead, the anticancer effect of omega-3 could derive from their effect in antagonizing the formation of such PG; it can be useful, therefore, to increase the dietary omega-3/omega-6 ratio. Moreover, the effects of omega-3 on the anatomic and functional central nervous system development and of their possible therapeutical use in some psychiatric pathologies were evaluated.     

Omega 3 polyunsaturated fatty acids and body weight

In animal studies, n-3 PUFA have been shown to influence body composition and to reduce the accumulation of body fat, thereby affecting body weight homeostasis. In addition, it has been suggested that an additional supply of n-3 PUFA during pregnancy or lactation, or both, would have a beneficial effect on birth weight and infant growth and development. The purpose of the present study was to systematically review interventional clinical trials on the effects of dietary n-3 PUFA supplementation on body weight in adult subjects and in infants whose mothers were supplemented with these fatty acids during pregnancy and/or lactation. A systematic search, focused on n-3 PUFA and body weight, and limited to controlled clinical trials, was performed in different databases. The quality of all included studies was assessed against set criteria, and results of eligible trials were compared. There were few studies targeting this topic. In adults, all of the five studies included, except for one, show no change in body weight by dietary supplementation with n-3 PUFA. Within those trials conducted in pregnant and/or lactating women in which a main outcome was birth weight or growth in infancy, two showed a modest increase in birth weight and the rest showed no effect. None of the trials showed an effect of maternal n-3 PUFA supplementation on infant's weight at the short term. However, it should be noted that a number of limitations, including a variety of experimental designs, type and doses of n-3 PUFA, and high attrition rates, among others, make impossible to draw robust conclusions from this review.     

Omega 3 fatty acids, gestation and pregnancy outcomes

Pregnancy is associated with a reduction in maternal serum docosahexaenoic acid (DHA, 22:6 n-3) percentage and its possible depletion in the maternal store. Since the synthesis of long chain polyunsaturated fatty acids (LCPUFA) in the fetus and placenta is low, both the maternal LCPUFA status and placental function are critical for their supply to the fetus. Maternal supplementation with DHA up to 1 g/d or 2·7 g n-3 LCPUFA did not have any harmful effect. DHA supplementation in large studies slightly the enhanced length of gestation (by about 2 days), which may increase the birth weight by about 50 g at delivery. However no advice can be given on their general using to avoid preterm deliveries in low or high risk pregnancies. Several studies, but not all, reported improvements of the offspring in some neurodevelopmental tests as a result of DHA supplementation during gestation, or, at least, positive relationships between maternal or cord serum DHA percentages and cognitive skills in young children. The effect seems more evident in children with low DHA proportions, which raises the question of how to identify those mothers who might have a poor DHA status and who could benefit from such supplementation. Most studies on the effects of n-3 LCPUFA supplementation during pregnancy on maternal depression were judged to be of low-to-moderate quality, mainly due to small sample sizes and failure to adhere to Consolidated Standards of Reporting Trials guidelines. In contrast, the effects of n-3 LCPUFA supplementation on reducing allergic diseases in offspring are promising.     

Levels of Omega 3 fatty acids in Australian seafood

The aim of this study was to determine the quantity of omega 3 (n-3) fatty acids in commonly consumed species of South Australian fish. Omega 3 fatty acids ranged from 17.7% to 53.7% of total fat with docosahexaenoic acid (DHA, 22:6n-3) as the major omega 3 fatty acid in all 26 species tested (range 9.5 % to 47.1% of total fat). The levels of total omega 6 (n-6) fatty acids ranged from 2.3% to 20.2% of total lipids, chiefly as arachidonic acid (AA, 20:4n-6). Fatty fish such as Gemfish, Atlantic Salmon and Swordfish were found to be good sources of omega-3 fatty acid (1360, 2252 and 2571 mg/100g fish respectively), while low fat fish such as Ling, Deep Sea Bream (Blue Warhou) and Blue Grenadier (0.5, 0.7 and 0.7% fat) had low levels of omega 3 fatty acid (222, 257 and 247 mg/100g). Because most white table fish consumed by Australians are so low in fat they are actually a limited source of omega 3 fats. The amount of fish required to be consumed to provide 1 g of omega 3 fatty acid per day ranged from 40 to 450 g.     

Omega 3 fatty acids and inborn errors of metabolism

A number of studies are investigating the role of n-3 polyunsaturated fatty acids in children with metabolic inborn errors, while the effects on visual and brain development in premature infants and neonates are well known. However, their function incertain chronic neurological, inflammatory and metabolic disorders is still under study. Standards should be established to help identify the need of docosahexaenoic acid supplementation in conditions requiring a restricted diet resulting in an altered metabolism system, and find scientific evidence on the effects of such supplementation. This study reviews relevant published literature to propose adequate n-3 intake or supplementation doses for different ages and pathologies. The aim of this review is to examine the effects of long chain polyunsaturated fatty acids supplementation in preventing cognitive impairment or in retarding its progress, and to identify nutritional deficiencies, in children with inborn errors of metabolism. Trials were identified from a search of the Cochrane and MEDLINE databases in 2011. These databases include all major completed and ongoing double-blind, placebo-controlled, randomized trials, as well as all studies in which omega-3 supplementation was administered to children with inborn errors, and studies assessing omega-3 fatty acids status in plasma in these pathologies. Although few randomized controlled trials met the inclusion criteria of this review, some evidenced that most of children with inborn errors are deficient in omega-3 fatty acids, and demonstrated that supplementation might improve their neural function, or prevent the progression of neurological impairment. Nontheless, further investigations are needed on this issue.     

Omega3 polyunsaturated fatty acids and maize flour diets.

OBJECTIVES: Nutrition disorders caused by a 6.5% maize protein diet (M), unbalanced in its indispensable amino acid pattern, provokes an arrest on cellular proliferation and maturation in the thymus of growing rats. We investigated the effect of diet supplementation with different amounts of omega3 polyunsaturated fatty acid (M = 0 mg/d, M1 = 12 mg/d, M2 = 24 mg/d, respectively) on thymus, plasma lipid concentrations, and hepatic tissue. METHODS: A well-nourished age-matched control group received stock diet from weaning. The animals (8 to 10 per group) received the diets for 9 d. At the end of the experimental period, they were killed, thymuses were removed, and cell number, absolute number of T cells labeled by the monoclonal antibody W3/13, plasma lipid profile (total cholesterol, triacylglycerols, high- and low-density lipoprotein cholesterols), and oxidative stress in hepatic tissue were determined. RESULTS: Only M2 reached the values of the control group when cell number and absolute number of T cells were compared. No statistical differences were observed among the M, M1, M2, and control group when high- and low-density lipoprotein cholesterols and hepatic lipid peroxidation were considered. CONCLUSIONS: The supplementation of a 6.5% maize protein diet with 24 mg/d of omega3 polyunsaturated fatty acid can recover the proliferation and absolute number of T cells labeled with W3/13 without affecting lipid profile and hepatic lipid peroxidation.     

Omega 3 fatty acids on child growth, visual acuity and neurodevelopment

The aim of this review is to evaluate the effects of omega-3 long chain polyunsaturated fatty acids (n-3 LCPUFA) supplementation in pregnant and lactating women and infants during postnatal life, on the visual acuity, psychomotor development, mental performance and growth of infants and children. Eighteen publications (11 sets of randomized control clinical trial [RCTs]) assessed the effects of the n-3 LCPUFA supplementation during pregnancy on neurodevelopment and growth, in the same subjects at different time points; 4 publications (2 data sets from RCTs) addressed physiological responses to n-3 LCPUFA supplementation during pregnancy & lactation and 5 publications (3 data sets from RCTs) exclusively during lactation. Some of these studies showed beneficial effects of docosahexaenoic acid (DHA) supplementation during pregnancy and/or lactation especially on visual acuity outcomes and some on long-term neurodevelopment; a few, showed positive effects on growth. There were also 15 RCTs involving term infants who received infant formula supplemented with DHA, which met our selection criteria. Many of these studies claimed a beneficial effect of such supplementation on visual, neural, or developmental outcomes and no effects on growth. Although new well designed and conducted studies are being published, evidence from RCTs does not demonstrate still a clear and consistent benefit of n-3 LCPUFA supplementation during pregnancy and/or lactation on term infants growth, neurodevelopment and visual acuity. These results should be interpreted with caution due to methodological limitations of the included studies.     

Omega 3 fatty acids and the brain: review of studies in depression

The brain is a lipid-rich organ containing mostly complex polar phospholipids, sphingolipids, gangliosides and cholesterol. These lipids are involved in the structure and function of cell membranes in the brain. The glycerophospholipids in the brain contain a high proportion of polyunsaturated fatty acids (PUFA) derived from the essential fatty acids, linoleic acid and alpha-linolenic acid. The main PUFA in the brain are docosahexaenoic acid (DHA, all cis 4,7,10,13,16,19-22:6) derived from the omega 3 fatty acid, alpha-linolenic acid, and arachidonic acid (AA, all cis 5,8,11,14-20:4) and docosatetraenoic acid (all cis 7,10,13,16-22:4), both derived from the omega 6 fatty acid, linoleic acid. Experimental studies in animals have shown that diets lacking omega 3 PUFA lead to substantial disturbances in neural function, which in most circumstances can be restored by the inclusion of omega 3 PUFA in the diet. In the past 10 years there has been an emerging interest in treating neuropsychological disorders (depression and schizophrenia) with omega 3 PUFA. This paper discusses the clinical studies conducted in the area of depression and omega 3 PUFA and the possible mechanisms of action of these PUFA. It is clear from the literature that DHA is involved in a variety of processes in neural cells and that its role is far more complex than simply influencing cell membrane properties.     

n 3 fatty acid proportions in plasma and cognitive performance in older adults

BACKGROUND: Very-long-chain n-3 polyunsaturated fatty acids (n-3 PUFAs) are suggested to be related to cognitive performance in older adults. However, limited data exist on the association between n-3 PUFAs and performance in specific cognitive domains. OBJECTIVE: We evaluated the association between plasma n-3 PUFA proportions and cognitive performance in 5 cognitive domains and determined whether plasma n-3 PUFA proportions predict cognitive change over 3 y. DESIGN: We used data from the FACIT trial, in which participants received folic acid or placebo capsules for 3 y. Fatty acid proportions in plasma cholesteryl esters at baseline were measured in 807 men and women aged 50-70 y. Cognitive performance for memory, sensorimotor speed, complex speed, information-processing speed, and word fluency was assessed at baseline and after 3 y. The cross-sectional analyses were based on all 807 participants; the longitudinal analyses were based only on 404 participants in the placebo group. RESULTS: Higher plasma n-3 PUFA proportions predicted less decline in sensorimotor speed (multiple linear regression coefficient, z score = 0.31; 95% CI: 0.06, 0.57) and complex speed (0.40; 95% CI: 0.10, 0.70) over 3 y. Plasma n-3 PUFA proportions did not predict 3-y changes in memory, information-processing speed, or word fluency. The cross-sectional analyses showed no association between plasma n-3 PUFA proportions and performance in any of the 5 cognitive domains. CONCLUSIONS: In this population, plasma n-3 PUFA proportions were associated with less decline in the speed-related cognitive domains over 3 y. These results need to be confirmed in randomized controlled trials.     

Plasma n-3 fatty acids and the risk of cognitive decline in older adults: the Atherosclerosis Risk in Communities Study

BACKGROUND: Plasma fatty acids may affect the risk of cognitive decline in older adults. OBJECTIVES: We prospectively studied the association between plasma fatty acids and cognitive decline in adults aged 50-65 y at baseline and conducted a subgroup analysis. DESIGN: From 1987 through 1989, the Atherosclerosis Risk in Communities (ARIC) Study analyzed plasma fatty acids in cholesteryl esters and phospholipids in whites residing in Minneapolis, MN. From 1990 through 1992 and from 1996 through 1998, 3 neuropsychological tests in the domains of delayed word recall, psychomotor speed, and verbal fluency were administered. We selected cutoffs for statistically reliable cognitive decline in each of these domains and a measure of global cognitive change computed by principal-components analysis. Multivariate logistic regression was conducted. Focusing on n-3 highly unsaturated fatty acids (HUFAs), a subgroup analysis assessed differential association across potential effect modifiers implicated in oxidative stress and increased risk of neurodegenerative disease. RESULTS: In the 2251 study subjects, the risk of global cognitive decline increased with elevated palmitic acid in both fractions and with high arachidonic acid and low linoleic acid in cholesteryl esters. Higher n-3 HUFAs reduced the risk of decline in verbal fluency, particularly in hypertensive and dyslipidemic subjects. No significant findings were shown for psychomotor speed or delayed word recall. CONCLUSIONS: Promoting higher intakes of n-3 HUFAs in the diet of hypertensive and dyslipidemic persons may have substantial benefits in reducing their risk of cognitive decline in the area of verbal fluency. However, clinical trials are needed to confirm this finding.     

天津市社区老年人MCI患病及影响因素分析

  目的  了解天津市社区老年人血脂水平与轻度认知障碍（MCI）发生的关系,为采取MCI相应的预防措施提供参考依据。  方法  采用以社区为基础1 : 1匹配的病例对照研究方法,于2016年3月在天津市王顶堤街道辖区内随机选取4个社区卫生服务中心,将体检时诊断为MCI的210例 ≥ 65岁老年人作为病例组,按病例组同性别、年龄（ ± 1岁）匹配210名认知正常老年人作为对照组,两组进行问卷调查和实验室检测,《精神障碍诊断和统计手册 – V》（DSM-V）用于诊断MCI,采用多因素条件logistic回归模型分析社区老年人血脂水平与MCI发生的关系。  结果  天津市病例组MCI社区老年人和对照组认知正常社区老年人的总胆固醇（TC）、低密度脂蛋白胆固醇（LDL-C）、高密度脂蛋白胆固醇（HDL-C）、LDL-C/HDL-C水平分别为186.50（160.75,215.00）mg/dL和195.50（168.00,217.25）mg/dL、101.00（77.75,121.00）mg/dL和100.00（79.75,123.00）mg/dL、58.50（46.75,71.25）mg/dL和58.00（47.00,70.00）mg/dL、1.71（1.30,2.35）和1.66（1.31,2.26）,2组老年人TC、LDL-C、HDL-C、LDL-C/HDL-C水平差异均无统计学意义（均P > 0.05）;在调整了文化程度及是否患高血压、糖尿病、心脏病、脑卒中等混杂因素后,多因素条件logistic回归分析结果显示,天津市TC为200 ~ 240 mg/dL社区老年人发生MCI的风险为 < 200 mg/dL社区老年人的0.52倍（OR = 0.52,95 % CI = 0.27 ~ 0.99）,HDL-C为 > 40 mg/dL社区老年人发生MCI的风险为 ≤ 40 mg/dL社区老年人的0.30倍（OR = 0.30,95 % CI = 0.14 ~ 0.67）,LDL-C为100 ~ 130 mg/dL、130 ~ 160 mg/dL和 > 160 mg/dL社区老年人发生MCI的风险分别为 < 100 mg/dL社区老年人的2.37倍（OR = 2.37,95 % CI = 1.21 ~ 4.65）、3.22倍（OR = 3.22,95 % CI = 1.09 ~ 9.49）和9.33倍（OR = 9.33,95 % CI = 1.59 ~ 54.61）,LDL-C/HDL-C为 > 2.30社区老年人发生MCI的风险为 < 1.31社区老年人的0.37倍（OR = 0.37,95 % CI = 0.16 ~ 0.88）。  结论  高水平的LDL-C为天津市社区老年人MCI发生的危险因素,而高水平的HDL-C和LDL-C/HDL-C比值及中等水平的TC则为天津市社区老年人MCI发生的保护因素。