Dietary fish oil and olive oil supplementation in patients with rheumatoid arthritis. Clinical and immunologic effects

Antiproliferative effect of docosahexaenoic acid on adult human keratinocytes in vitro / Antiproliferativni efekat dokosaheksanoične kiseline na adultne humane keratinocite in vitro

Numerous clinical studies demonstrate benefits of dietary supplementation with fish oils in autoimmune diseases and other inflammatory diseases such as psoriasis, multiple sclerosis, systemic lupus erythematodes and so on. Docosahexaenoic acid (DHA) is an omega-3 fatty acid which is abundantly found in fish oil. In the present study we investigated effects of DHA on proliferation of human keratinocytes established from skin of seven adult donors, cultivated in growth medium that allows optimal cell proliferation. We found a dose-dependent inhibition of cell proliferation when keratinocytes were incubated with 6.25, 12.5 and 25 -μM of DHA. Inhibition of proliferative capacity considerably varied in keratinocyte cultures derived from different donors, particularly when incubated with the lowest concentration of the assessed substance. Lactate dehydrogenase-release assay excluded necrosis of cultivated keratinocytes as a cause of decreased proliferation. Our results suggest that DHA may potentially be used as a routine adjuvant therapy, with classical therapy of inflammatory hyperproliferative skin diseases.

Long-term moderate intervention with n-3 long-chain PUFA-supplemented dairy products: effects on pathophysiological biomarkers in patients with rheumatoid arthritis

n-3 long-chain PUFA (n-3 LC-PUFA) may improve cardiovascular and inflammatory diseases. The effects of n-3 LC-PUFA-supplemented dairy products on inflammation and immunological parameters, biomarkers of oxidative stress, serum lipids, and on disease activity were determined in patients with rheumatoid arthritis (RA). Forty-five subjects (forty-three females and two males) were randomly divided into two groups in a double-blind, placebo-controlled cross-over study. Both groups received placebo or verum products consecutively for 3 months with a 2-month washout phase between the two periods. Blood samples were taken at the beginning and at the end of each period. The dairy products generally improved serum lipids by increasing HDL and lowering lipoprotein a. The n-3 LC-PUFA supplements act to lower TAG. Additionally, a decreased lipopolysaccharide-stimulated cylo-oxygenase-2 expression was found in patients who had consumed the enriched dairy products. The majority of the CD analysed were not influenced, although n-3 LC-PUFA did suppress the immune response as lymphocytes and monocytes were found to be significantly decreased. The n-3 LC-PUFA did not increase the biomarkers of oxidative stress such as 8-iso-PGF(2alpha) and 15-keto-dihydro PGF(2alpha), and DNA damage like 7,8-dihydro-8-oxo-2'-deoxyguanosine. The long-term consumption of dairy products (2 x 12 weeks) diminished the excretion of hydroxypyridinium crosslinks, and favoured the diastolic blood pressure. The consumption of moderate doses of n-3 LC-PUFA in combination with dairy products did not improve the disease activity. However, there is evidence of cardioprotective effects. Furthermore, the long-term consumption of dairy products acts against the cartilage and bone destruction in RA.

Effects of feeding fish oil on mesenteric lymph node cytokine responses in obese leptin receptor-deficient JCR:LA-cp rats

OBJECTIVE

berrant immune responses have been identified in obesity; however, immune cells of lymph nodes residing in the inflammatory environment of visceral adipose tissue have been largely overlooked. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) can reduce inflammation and modify T-cell function and therefore may improve immune function in obesity. Thus, we determined the effects of feeding fish oil (FO) containing EPA and DHA on mesenteric lymph node (MLN) immune cell function.

METHODS

In this study, 14-week-old obese, leptin receptor-deficient JCR:LA-cp rats (cp/cp) (n=10 per group) were randomized to one of three nutritionally adequate diets for 3 weeks: control (ctl, 0% EPA+DHA), low FO (LFO, 0.8% w/w EPA+DHA) or high FO (HFO, 1.4% w/w EPA+DHA). Lean JCR:LA-cp (Cp/cp or Cp/Cp) rats (n=5) were fed ctl diet. MLN cell phospholipid (PL) fatty acid composition, phenotypes and cytokine production were measured.

RESULTS

Obese ctl rats produced more IL-1beta, IL-4 and IL-10, despite a higher proportion of (n-3) polyunsaturated fatty acids (PUFAs) and a lower (n-6):(n-3) PUFA ratio in MLN PL compared with lean ctl rats (P<0.05). Concanavalin A-stimulated IL-2 production did not differ from lean rats even though obese ctl rats had a lower proportion of CD4(+)CD25(+) cells (P<0.05). Feeding FO to obese rats increased the incorporation of (n-3) PUFA into MLN PL and normalized production of IL-1beta (HFO only), IL-4 and IL-10 to the levels similar to lean ctl rats (P<0.05).

CONCLUSION

We demonstrate for the first time that obese JCR:LA-cp rats have impaired responses of MLN immune cells to mitogen stimulation and altered PL fatty acid composition. Feeding FO lowered the ex vivo inflammatory response (HFO only) and production of Th2 cytokines, without changing IL-2 production from ConA-stimulated splenocytes, which may occur independent of leptin signalling.

Dietary omega-3 fats for treatment of inflammatory joint disease: efficacy and utility

There is high level evidence (meta-analysis of randomized, controlled trials) for symptomatic benefits from fish oil use in rheumatoid arthritis, and there is biologic plausibility for its clinical effects. Fish oil also has safety advantages in reducing cardiovascular risk via direct cardiovascular effects and via nonsteroidal anti-inflammatory drug-sparing. This is an important aspect of fish oil use, given the increased cardiovascular risk in rheumatoid arthritis. Perceived barriers to clinical use are readily addressed.

Session 3: Joint Nutrition Society and Irish Nutrition and Dietetic Institute Symposium on ‘Nutrition and autoimmune disease’ PUFA, inflammatory processes and rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease manifested by swollen and painful joints, bone erosion and functional impairment. The joint lesions are characterised by infiltration of T lymphocytes, macrophages and B lymphocytes into the synovium and by synovial inflammation involving eicosanoids, cytokines and matrix metalloproteinases. In relation to inflammatory processes, the main fatty acids of interest are the n-6 PUFA arachidonic acid, which is the precursor of inflammatory eicosanoids such as PGE2 and leukotriene B4, and the n-3 PUFA EPA and DHA, which are found in oily fish and fish oils. Eicosanoids derived from the n-6 PUFA arachidonic acid play a role in RA, and the efficacy of non-steroidal anti-inflammatory drugs in RA indicates the importance of pro-inflammatory cyclooxygenase pathway products of arachidonic acid in the pathophysiology of the disease. EPA and DHA inhibit arachidonic acid metabolism to inflammatory eicosanoids. EPA also gives rise to eicosanoid mediators that are less inflammatory than those produced from arachidonic acid and both EPA and DHA give rise to resolvins that are anti-inflammatory and inflammation resolving. In addition to modifying the lipid mediator profile, n-3 PUFA exert effects on other aspects of immunity relevant to RA such as antigen presentation, T-cell reactivity and inflammatory cytokine production. Fish oil has been shown to slow the development of arthritis in an animal model and to reduce disease severity. Randomised clinical trials have demonstrated a range of clinical benefits in patients with RA that include reducing pain, duration of morning stiffness and use of non-steroidal anti-inflammatory drugs.

Eicosapentaenoic acid inhibits interleukin-6 production in interleukin-1beta-stimulated C6 glioma cells through peroxisome proliferator-activated receptor-gamma

Epidemiological studies suggest that intake of omega-3 polyunsaturated fatty acids improves neurological disorders such as Alzheimer's disease which exhibit inflammatory pathology. We therefore investigated the anti-inflammatory effects of eicosapentaenoic acid (EPA) on interleukin (IL)-1beta-stimulated C6 glioma cells. In the present study, EPA inhibited pro-inflammatory cytokine IL-6 production, a characteristic of certain neurodegenerative disorders, in IL-1beta-stimulated C6 glioma cells in dose-dependent fashion. EPA down-regulated the expression of IL-6 at mRNA level, indicating that the effect of EPA occurs at the transcriptional level. In addition, peroxisome proliferator-activated receptor (PPAR) gamma antagonists abolished the inhibitory effect of EPA on IL-1beta-induced IL-6 production, whereas PPARalpha antagonist did not block the inhibitory effect of EPA. EPA might thus contribute to the regulation of pro-inflammatory cytokine production in astrocytes through interaction with PPARgamma. Among the PPARgamma ligands tested in this study, ciglitazone, a synthetic agonist of PPARgamma, effectively inhibited IL-6 production, but while neither rosiglitazone nor 15-deoxy-Delta(12,14)-prostaglandin J2 did. These findings indicate that the coordination of PPAR gamma ligands is important in inhibiting the production of IL-6 in C6 glioma cells.

Towards a nutritional approach for prevention of Alzheimer's disease: Biochemical and cellular aspects

Alzheimer's disease (AD) is a major public health concern in all countries. Although the precise cause of AD is still unknown, a growing body of evidence supports the notion that soluble amyloid beta-peptide (Abeta) may be the proximate cause of synaptic injuries and neuronal death early in the disease. AD patients display lower levels of docosahexaenoic acid (DHA, C22:6 ; n-3) in plasma and brain tissues as compared to age-matched controls. Furthermore, epidemiological studies suggest that high DHA intake might have protective properties against neurodegenerative diseases. These observations are supported by in vivo studies showing that DHA-rich diets limits the synaptic loss and cognitive defects induced by Abeta peptide. Although the molecular basis of these neuroprotective effects remains unknown, several mechanisms have been proposed such as (i) regulation of the expression of potentially protective genes, (ii) activation of anti-inflammatory pathways, (iii) modulation of functional properties of the synaptic membranes along with changes in their physicochemical and structural features.

Significance of olive oil in the host immune resistance to infection

The effects exerted by polyunsaturated fatty acids (PUFA) on immune system functions have been investigated in recent years. These studies have reported the important role thatn-3 PUFA play in the diminution of incidence and severity of inflammatory disorders. Nevertheless, less attention has been paid to the action of monounsaturated fatty acids (MUFA) upon the immune system. The administration of a diet containing a high amount of olive oil in experimental animals produces a suppression of lymphocyte proliferation, an inhibition of cytokine production and a reduction in natural killer (NK) cell activity. Despite these alterations in immune functions, it has been reported that olive oil-rich diets are not as immunosuppressive as fish oil diets. An important aspect in immunonutrition is focused on the relationship between fats, the immune system and host resistance to infection, particularly when these nutrients are supplied to patients at risk of sepsis. Different studies have determined that olive oil-rich diets do not impair the host resistance to infection. Therefore, olive oil constitutes a suitable fat that may be applied in clinical nutrition and administered to critically ill patients. In the present review, we summarize the current knowledge on olive oil and immune system functions, the biological consequences derived from the administration of diets containing olive oil and the impact of olive oil on immune defence.

1-Tetradecanol complex reduces progression of Porphyromonas gingivalis-induced experimental periodontitis in rabbits

BACKGROUND

It has been recently shown that monounsaturated fatty acids inhibit endothelial activation and reduce tissue responsiveness to cytokines. The present study has been planned to investigate topical application of a novel monounsaturated fatty acid complex (1-tetradecanol complex) for prevention of Porphyromonas gingivalis-induced periodontitis in rabbits.

METHODS

Experimental periodontitis was induced in New Zealand white rabbits with silk sutures tied around the mandibular second premolars bilaterally, followed by the topical application of 10(9) colony forming units (CFU) of P. gingivalis. 1-Tetradecanol complex (1-TDC) was topically applied at 1- and 10-mg/ml concentrations in five animals in each group, whereas control animals received olive oil vehicle (five animals) three times per week for 6 weeks. Negative controls included ligature alone (14 animals) or ligature + P. gingivalis (non-treatment; 15 animals). Rabbits were sacrificed after 6 weeks, and mandibular block sections were obtained; tissues were decalcified and embedded in paraffin. Thin sections (5 microm) were stained with hematoxylin and eosin or tartrate-resistant acid phosphatase. Macroscopic and histologic evaluation of samples was followed by the characterization of cellular inflammatory infiltrate and quantitative histomorphometric measurements.

RESULTS

Treatment with both concentrations of 1-TDC and vehicle resulted in significant prevention of macroscopic periodontal inflammation and bone loss (75%; P <0.05) compared to the non-treatment (ligature + P. gingivalis) group, where significant periodontal tissue destruction characterized by attachment and bone loss was detected. However, there was no statistically significant difference between the vehicle and both 1-TDC groups. Histologically, 1-TDC inhibited inflammatory cell infiltration and prevented osteoclastogenesis, whereas treatment with vehicle did not show the same effect as in the 1-TDC groups; the difference between vehicle and the higher concentration of 1-TDC (10 mg/ml) was statistically significant.

CONCLUSION

Topical application of an esterified monounsaturated fatty acid complex (1-TDC) was found promising in preventing bone loss, inflammatory cell infiltration, and connective tissue destruction in the rabbit periodontitis model.

Differential immunomodulation with long-chain n-3 PUFA in health and chronic disease

The balance of intake of n-6 and n-3 PUFA, and consequently their relative incorporation into immune cells, is important in determining the development and severity of immune and inflammatory responses. Some disorders characterised by exaggerated inflammation and excessive formation of inflammatory markers have become among the most important causes of death and disability in man in modern societies. The recognition that long-chain n-3 PUFA have the potential to inhibit (excessive) inflammatory responses has led to a large number of clinical investigations with these fatty acids in inflammatory conditions as well as in healthy subjects. The present review explores the presence of dose-related effects of long-chain n-3 PUFA supplementation on immune markers and differences between healthy subjects and those with inflammatory conditions, because of the important implications for the transfer of information gained from studies with healthy subjects to patient populations, e.g. for establishing dose levels for specific applications. The effects of long-chain n-3 PUFA supplementation on ex vivo lymphocyte proliferation and cytokine production by lymphocytes and monocytes in healthy subjects have been studied in twenty-seven, twenty-five and forty-six treatment cohorts respectively, at intake levels ranging from 0.2 g EPA+DHA/d to 7.0 g EPA+DHA/d. Most studies, particularly those with the highest quality study design, have found no effects on these immune markers. Significant effects on lymphocyte proliferation are decreased responses in seven of eight cohorts, particularly in older subjects. The direction of the significant changes in cytokine production by lymphocytes is inconsistent and only found at supplementation levels > or =2.0 g EPA+DHA/d. Significant changes in inflammatory cytokine production by monocytes are decreases in their production in all instances. Overall, these studies fail to reveal strong dose-response effects of EPA+DHA on the outcomes measured and suggest that healthy subjects are relatively insensitive to immunomodulation with long-chain n-3 PUFA, even at intake levels that substantially raise their concentrations in phospholipids of immune cells. In patients with inflammatory conditions cytokine concentrations or production are influenced by EPA+DHA supplementation in a relatively large number of studies. Some of these studies suggest that local effects at the site of inflammation might be more pronounced than systemic effects and disease-related markers are more sensitive to the immunomodulatory effects, indicating that the presence of inflamed tissue or 'sensitised' immune cells in inflammatory disorders might increase sensitivity to the immunomodulatory effects of long-chain n-3 PUFA. In a substantial number of these studies clinical benefits related to the inflammatory state of the condition have been observed in the absence of significant effects on immune markers of inflammation. This finding suggests that condition-specific clinical end points might be more sensitive markers of modulation by EPA+DHA than cytokines. In general, the direction of immunomodulation in healthy subjects (if any) and in inflammatory conditions is the same, which indicates that studies in healthy subjects are a useful tool to describe the general principles of immunomodulation by n-3 PUFA. However, the extent of the effect might be very different in inflammatory conditions, indicating that studies in healthy subjects are not particularly suitable for establishing dose levels for specific applications in inflammatory conditions. The reviewed studies provide no indications that the immunomodulatory effects of long-chain n-3 PUFA impair immune function or infectious disease resistance. In contrast, in some conditions the immunomodulatory effects of EPA+DHA might improve immune function.

A meta-analysis of the analgesic effects of omega-3 polyunsaturated fatty acid supplementation for inflammatory joint pain

Between 40% and 60% of Americans use complementary and alternative medicine to manage medical conditions, prevent disease, and promote health and well-being. Omega-3 polyunsaturated fatty acids (omega-3 PUFAs) have been used to treat joint pain associated with several inflammatory conditions. We conducted a meta-analysis of 17 randomized, controlled trials assessing the pain relieving effects of omega-3 PUFAs in patients with rheumatoid arthritis or joint pain secondary to inflammatory bowel disease and dysmenorrhea. Meta-analysis was conducted with Cochrane Review Manager 4.2.8. for six separate outcomes using standardized mean differences (SMDs) as a measure of effect size: (1) patient assessed pain, (2) physician assessed pain, (3) duration of morning stiffness, (4) number of painful and/or tender joints, (5) Ritchie articular index, and (6) nonselective nonsteroidal anti-inflammatory drug consumption. Supplementation with omega-3 PUFAs for 3-4 months reduces patient reported joint pain intensity (SMD: -0.26; 95% CI: -0.49 to -0.03, p=0.03), minutes of morning stiffness (SMD: -0.43; 95% CI: -0.72 to -0.15, p=0.003), number of painful and/or tender joints (SMD: -0.29; 95% CI: -0.48 to -0.10, p=0.003), and NSAID consumption (SMD: -0.40; 95% CI: -0.72 to -0.08, p=0.01). Significant effects were not detected for physician assessed pain (SMD: -0.14; 95% CI: -0.49 to 0.22, p=0.45) or Ritchie articular index (SMD: 0.15; 95% CI: -0.19 to 0.49, p=0.40) at 3-4 months. The results suggest that omega-3 PUFAs are an attractive adjunctive treatment for joint pain associated with rheumatoid arthritis, inflammatory bowel disease, and dysmenorrhea.

Picking a bone with contemporary osteoporosis management: Nutrient strategies to enhance skeletal integrity

Epidemic rates of osteoporosis in the western world have yielded intense efforts to develop management approaches to combat this potentially devastating disorder; recent research has unveiled innovative strategies which hold considerable promise for prevention of skeletal compromise and amelioration of suboptimal bone health. According to many algorithms and practice directives, the contemporary assessment and management of osteoporosis focuses heavily on determination of fracture risk and pharmaceutical intervention for those patients deemed to be at high risk. While routine recommendations for calcium and vitamin D have been incorporated into most regimens, disproportionately little attention has been given to recent research elucidating improved bone health and diminution in fracture rates experienced by patients receiving specific nutrients. In mainstream medical practice, clinical analysis and management of nutritional or dietary issues is sometimes perceived as unconventional, primitive or unsophisticated health care. Recent evidence-based research, however, supports intervention with adequate amounts of specific nutrients including vitamin D, strontium, vitamin K, and essential fatty acids in the prevention and primary management of osteoporosis.

Modulation of lipid rafts by Omega-3 fatty acids in inflammation and cancer: implications for use of lipids during nutrition support

Current understanding of biologic membrane structure and function is largely based on the concept of lipid rafts. Lipid rafts are composed primarily of tightly packed, liquid-ordered sphingolipids/cholesterol/saturated phospholipids that float in a sea of more unsaturated and loosely packed, liquid-disordered lipids. Lipid rafts have important clinical implications because many important membrane-signaling proteins are located within the raft regions of the membrane, and alterations in raft structure can alter activity of these signaling proteins. Because rafts are lipid-based, their composition, structure, and function are susceptible to manipulation by dietary components such as omega-3 polyunsaturated fatty acids and by cholesterol depletion. We review how alteration of raft lipids affects the raft/nonraft localization and hence the function of several proteins involved in cell signaling. We focus our discussion of raft-signaling proteins on inflammation and cancer.

Protective effect of Mediterranean fish oil extracts on heat-induced denaturation of albumin

Three oily extracts, obtained by acetone extraction from the entrails of different varieties of Mediterranean fishes, such as mackerel (Scomber scombrus), sardine (Sardina pilchardus) and horse mackerel (Trachurus mediterraneus), were characterized to determine their unsaturated fatty acid content. In an in-vitro model, their inhibitory effect was then evaluated against protein aggregation and their protective efficacy against heat-induced albumin denaturation assessed. The fish oil extracts tested in this study presented a significant amount of unsaturated fatty acids; in particular the extract obtained from the entrails of horse mackerel proved to have higher concentrations of DHA (docosahexaenoic acid) and oleic acid compared with the other two oils. The in-vitro study revealed an interesting protective effect of the oil extracts (particularly the horse mackerel extract) against heat-induced denaturation of albumin.

Fish oil: what the prescriber needs to know

There is a general belief among doctors, in part grounded in experience, that patients with arthritis need nonsteroidal anti-inflammatory drugs (NSAIDs). Implicit in this view is that these patients require the symptomatic relief provided by inhibiting synthesis of nociceptive prostaglandin E₂, a downstream product of the enzyme cyclo-oxygenase (COX), which is inhibited by NSAIDs. However, the concept of 'safe' NSAIDs has collapsed following a multiplicity of observations establishing increased risk for cardiovascular events associated with NSAID use, especially but not uniquely with the new COX-2-selective NSAIDs. This mandates greater parsimony in the use of these agents. Fish oils contain a natural inhibitor of COX, reduce reliance on NSAIDs, and reduce cardiovascular risk through multiple mechanisms. Fish oil thus warrants consideration as a component of therapy for arthritis, especially rheumatoid arthritis, in which its symptomatic benefits are well established. A major barrier to the therapeutic use of fish oil in inflammatory diseases is ignorance of its mechanism, range of beneficial effects, safety profile, availability of suitable products, effective dose, latency of effects and instructions for administration. This review provides an evidence-based resource for doctors and patients who may choose to prescribe or take fish oil.

Beneficial effects of docosahexaenoic acid on active avoidance performance in 1K-1C hypertensive rats

The present study evaluated the role of chronic docosahexaenoic acid (DHA) supplementation on active avoidance learning task performance in experimental hypertension. Male Wistar rats were randomly divided into five experimental groups as follows: control, sham, DHA treated, 1K-1C hypertensive, and 1K-1C hypertensive+DHA treated. Hypertension was induced in 1K-1C rats via placing a silver clip (0.20-mm ID) around the left renal artery following a right uninephrectomy. DHA (36 mg/kg/day) was given to the treatment groups for 60 days by gastric gavage. Arterial blood pressure was measured by using the tail-cuff method. Active avoidance responses were determined by an automated shuttle-box. In brain (cerebrum) and hippocampus tissues, thiobarbituric acid reactive substances (TBARS) and nitrite levels were measured by fluorometric methods. DHA supplementation decreased blood pressure in hypertensive rats. Data from active avoidance training indicated that performance of active avoidance learning tasks were significantly impaired in 1K-1C hypertensive rats, but was completely restored by DHA supplementation. Increased cerebrum TBARS levels in 1K-1C rats were abolished by DHA administration. Cerebrum nitrite levels were lower in the DHA, 1K-1C and 1K-1C+DHA treated groups compared to controls. Hippocampus nitrite levels were lower in DHA treated and 1K-1C hypertensive rats compared to controls and higher in 1K-1C+DHA treated rats compared to the 1K-1C group. Our data indicates that DHA supplementation improves the performance of active avoidance learning tasks which is impaired in experimental hypertension. These affirmative changes might be due to a DHA-induced decrease in lipid peroxidation which may in turn limit the consumption of nitric oxide (NO) which promotes active avoidance learning.

Incidence and Prevalence of Rheumatoid Arthritis, Based on the 1987 American College of Rheumatology Criteria: A Systematic Review

OBJECTIVES

To conduct a systematic review of incidence and prevalence studies of rheumatoid arthritis (RA), based on the 1987 revised American College of Rheumatology (ACR) criteria, to compare their methodologies and summarize their results, and to investigate the possible geographic variations and changes over time in the frequency of the disease.

METHODS

We conducted a Medline search between January 1988 and December 2005. Studies reporting the incidence and prevalence of RA in adult populations (16 to 20 years and over), based on 1987 ACR criteria, were eligible for inclusion. From each study included, we extracted the country, year of publication, type of study (retrospective, prospective, or cross-sectional), and incidence or prevalence rates. The study areas were grouped into (a) North American countries; (b) north European countries; (c) south European countries; and (d) developing countries. We examined the geographical differences of prevalence and incidence rates using the Mann-Whitney and the Kruskall-Wallis tests.

RESULTS

A total of 28 studies were identified meeting the inclusion criteria. Nine were incidence studies, 17 were prevalence studies, and 2 estimated both prevalence and incidence rates. Incidence studies were not available from developing countries. There is a significant difference of prevalence estimates between northern European and American countries and developing countries. South European countries have lower median incidence rates than North American and north European countries. As concerning the time trends of RA occurrence, only 3 incidence studies provided secular data from the same study area, based on ACR criteria, using the same methods of case ascertainment. Two of these studies indicate a decreasing incidence of RA in Finland and United States of America.

CONCLUSIONS

The occurrence of RA varies among countries and areas of the world. A decreasing trend has been observed in countries characterized by high rates of RA incidence and prevalence. However, the relatively small number of studies for most areas of the world and the lack of incidence studies for the developing countries limits the understanding of worldwide RA epidemiology.

Fatty acids as modulators of the immune response

Research describing fatty acids as modulators of inflammation and immune responses abounds. Many of these studies have focused on one particular group of fatty acids, omega-3. The data from animal studies have shown that these fatty acids can have powerful anti-inflammatory and immunomodulatory activities in a wide array of diseases (e.g., autoimmunity, arthritis, and infection). However, the evidence from human trials is more equivocal. In this review, a historical framework for understanding how and why fatty acids may affect the immune system is provided. Second, highlights of two recent landmark reports from the Agency for Healthcare Research and Quality are presented. These reports critically evaluate the evidence from human clinical trials of omega-3 fatty acids and rheumatoid arthritis, asthma, and a few other immune-mediated diseases. Third, the data from human clinical trials investigating the impact of various bioactive fatty acids on ex vivo and in vivo immune response are reviewed. Limitations in experimental design and immune assays commonly used are discussed. The discordance between expectation and evidence in this field has been a disappointment. Recommendations for improving both animal-based and human studies are provided.

Dietary intakes of fat and antioxidant vitamins are predictors of subclinical inflammation in overweight Swiss children

BACKGROUND

In obese children, subclinical inflammation is often present and is correlated with the metabolic syndrome. Dietary factors, such as fatty acids and antioxidants, potentially modulate the association between adiposity and subclinical inflammation, but few data are available in children.

OBJECTIVE

The aim of the study was to determine whether dietary fat or antioxidant intakes influence circulating tumor necrosis factor alpha (TNF-alpha), interleukin 6 (IL-6), C-reactive protein (CRP), and leptin concentrations in overweight children.

DESIGN

In a cross-sectional study of 6-14-y-old normal-weight (n = 33), overweight (n = 19), and obese (n = 27) Swiss children, nutritional intakes were assessed from two 24-h dietary recalls and a 1-d dietary record. Percentage body fat from skinfold thicknesses, waist-hip ratio, and blood pressure were measured. Fasting blood samples were collected for the measurement of insulin, glucose, HDL-cholesterol, triacylglycerol, CRP, IL-6, TNF-alpha, and leptin concentrations.

RESULTS

CRP, IL-6, and leptin increased significantly (P < 0.02) with increasing adiposity, independent of age; TNF-alpha did not increase. Total dietary fat and the percentage of energy from fat were significant predictors of CRP concentration, independent of body mass index (P < 0.05). Meat intake was a significant predictor of IL-6 and leptin, independent of body mass index (P < 0.05). Intakes of antioxidant vitamins (vitamins E and C and beta-carotene) were significant predictors of leptin (P < 0.05) but not of CRP, IL-6, or TNF-alpha.

CONCLUSIONS

Overweight Swiss children as young as 6 y have elevated concentrations of inflammatory markers. Intakes of total fat and antioxidant vitamins are determinants of subclinical inflammation in this age group.

Intravenous application of omega-3 fatty acids in patients with active rheumatoid arthritis. The ORA-1 trial. An open pilot study

The objective of this work was to assess the therapeutic efficacy and tolerability of intravenously applied n-3-PUFA in patients with active rheumatoid arthritis (RA). Thirty-four patients with active RA [identified as having a DAS28 (disease activity score including a 28 joint count) > 4.0] were enrolled into this 5-wk open pilot study (one group design). From the time of screening (visit 0, or V0), background therapy had to remain unchanged. Patients received 2 mL/kg (= 0.1-0.2 g fish oil/kg) fish oil emulsion intravenously on 7 consecutive days (Visit 1-Visit 2, or V1-V2) in addition to their background therapy. A decrease of the DAS28 > 0.6 at day 8 (Visit 2) was the primary efficacy measure. Moreover, the DAS28 at day 35 (Visit 3, or V3), the modified Health Assessment Questionnaire, the American College of Rheumatology (ACR) response criteria (V2, V3) and the Short Form-36 (V3) were assessed. Thirty-three patients completed the trial. The mean DAS28 at V1 was 5.45;at V2, 4.51 (P < .001 V1-V2) and at V3, 4.73 (P < .001 V1-V3; V2-V3, not significantly different). Of the 34 patients, 56% achieved a reduction of the DAS28 > 0.6 at V2 (mean 1.52); 27% > 1.2. At V3, 41% of the patients showed a DAS28 reduction > 0.6 (mean 1.06), and 36% > 1.2. ACR 20 and 50% responses at V2 were seen in 29 and 12% of patients, respectively; at V3, the comparable values were 18 and 9%, respectively. Overall tolerability was excellent. Intravenous application of n-3-PUFA (as an add-on therapy) was considerably well tolerated and led to improvement of the disease activity status in a reasonable number of RA patients. Future trials are warranted to answer whether the intravenous application of n-3-PUFA constitutes a therapeutic option in RA patients.

n-3 polyunsaturated fatty acids, inflammation, and inflammatory diseases

Inflammation is part of the normal host response to infection and injury. However, excessive or inappropriate inflammation contributes to a range of acute and chronic human diseases and is characterized by the production of inflammatory cytokines, arachidonic acid-derived eicosanoids (prostaglandins, thromboxanes, leukotrienes, and other oxidized derivatives), other inflammatory agents (e.g., reactive oxygen species), and adhesion molecules. At sufficiently high intakes, long-chain n-3 polyunsaturated fatty acids (PUFAs), as found in oily fish and fish oils, decrease the production of inflammatory eicosanoids, cytokines, and reactive oxygen species and the expression of adhesion molecules. Long-chain n-3 PUFAs act both directly (e.g., by replacing arachidonic acid as an eicosanoid substrate and inhibiting arachidonic acid metabolism) and indirectly (e.g., by altering the expression of inflammatory genes through effects on transcription factor activation). Long-chain n-3 PUFAs also give rise to a family of antiinflammatory mediators termed resolvins. Thus, n-3 PUFAs are potentially potent antiinflammatory agents. As such, they may be of therapeutic use in a variety of acute and chronic inflammatory settings. Evidence of their clinical efficacy is reasonably strong in some settings (e.g., in rheumatoid arthritis) but is weak in others (e.g., in inflammatory bowel diseases and asthma). More, better designed, and larger trials are required to assess the therapeutic potential of long-chain n-3 PUFAs in inflammatory diseases. The precursor n-3 PUFA alpha-linolenic acid does not appear to exert antiinflammatory effects at achievable intakes.

Time for an oil check: the role of essential omega-3 fatty acids in maternal and pediatric health

Deficiency of omega-3 fatty acids (omega3FAs) is an often unrecognized determinant of clinical disease; the adequate availability of these essential nutrients may prevent affliction or facilitate health restoration in some pregnant women and developing offspring. The human organism requires specific nutrients in order to carry out the molecular processes within cells and tissues and it is well established that omega3FAs are essential lipids necessary for various physiological functions. Accordingly, to achieve optimal health for patients, care givers should be familiar with clinical aspects of nutritional science, including the assessment of nutritional status and judicious use of nutrient supplementation. In view of the mounting evidence implicating omega3FA deficiency as a determinant of various maternal and pediatric afflictions, physicians should consider recommending purified fish oil supplementation during pregnancy and lactation. Furthermore, omega3FA supplementation may be indicated in selected pediatric situations to promote optimal health among children.

Fish oils--adjuvant therapy in chronic heart failure?

Despite advances in medical management and device therapy, chronic heart failure (CHF) remains a condition of high mortality and poor quality of life. Patients with CHF endure frequent admissions to hospital, with exacerbations of breathlessness or recurrent acute myocardial infarction and have a high incidence of sudden death. A high intake of marine polyunsaturated fatty acids (PUFAs) is associated with lower cardiovascular mortality in the general population, and diabetics, and can reduce cardiovascular deaths post-infarction. Many of the effects of PUFAs could be of benefit in CHF patients. They can improve endothelial function, reduce vascular tone, reduce platelet aggregability, improve myocardial relaxation, stabilize myocardial cells by prolonging the refractory period, and lead to increased appetite and weight gain. They also have potentially important immune-modulating effects, reducing cytokine production and release and altering prostaglandin metabolism. In this review article we discuss the potential benefits of PUFA supplementation in CHF patients using data from clinical trials and in vitro experiments.

Omega-3 fatty acids (fish oil) as an anti-inflammatory: an alternative to nonsteroidal anti-inflammatory drugs for discogenic pain

BACKGROUND

The use of NSAID medications is a well-established effective therapy for both acute and chronic nonspecific neck and back pain. Extreme complications, including gastric ulcers, bleeding, myocardial infarction, and even deaths, are associated with their use. An alternative treatment with fewer side effects that also reduces the inflammatory response and thereby reduces pain is believed to be omega-3 EFAs found in fish oil. We report our experience in a neurosurgical practice using fish oil supplements for pain relief.

METHODS

From March to June 2004, 250 patients who had been seen by a neurosurgeon and were found to have nonsurgical neck or back pain were asked to take a total of 1200 mg per day of omega-3 EFAs (eicosapentaenoic acid and decosahexaenoic acid) found in fish oil supplements. A questionnaire was sent approximately 1 month after starting the supplement.

RESULTS

Of the 250 patients, 125 returned the questionnaire at an average of 75 days on fish oil. Seventy-eight percent were taking 1200 mg and 22% were taking 2400 mg of EFAs. Fifty-nine percent discontinued to take their prescription NSAID medications for pain. Sixty percent stated that their overall pain was improved, and 60% stated that their joint pain had improved. Eighty percent stated they were satisfied with their improvement, and 88% stated they would continue to take the fish oil. There were no significant side effects reported.

CONCLUSIONS

Our results mirror other controlled studies that compared ibuprofen and omega-3 EFAs demonstrating equivalent effect in reducing arthritic pain. omega-3 EFA fish oil supplements appear to be a safer alternative to NSAIDs for treatment of nonsurgical neck or back pain in this selective group.

A role for direct interactions in the modulation of rhodopsin by omega-3 polyunsaturated lipids

Rhodopsin, the G protein-coupled receptor primarily responsible for sensing light, is found in an environment rich in polyunsaturated lipid chains and cholesterol. Biophysical experiments have shown that lipid unsaturation and cholesterol both have significant effects on rhodopsin's stability and function; omega-3 polyunsaturated chains, such as docosahexaenoic acid (DHA), destabilize rhodopsin and enhance the kinetics of the photocycle, whereas cholesterol has the opposite effect. Here, we use molecular dynamics simulations to investigate the possibility that polyunsaturated chains modulate rhodopsin stability and kinetics via specific direct interactions. By analyzing the results of 26 independent 100-ns simulations of dark-adapted rhodopsin, we found that DHA routinely forms tight associations with the protein in a small number of specific locations qualitatively different from the nonspecific interactions made by saturated chains and cholesterol. Furthermore, the presence of tightly packed DHA molecules tends to weaken the interhelical packing. These results are consistent with recent NMR work, which proposes that rhodopsin binds DHA, and they suggest a molecular rationale for DHA's effects on rhodopsin stability and kinetics.

Diet and rheumatoid arthritis: a review of the literature

INTRODUCTION

Rheumatoid arthritis is a common inflammatory condition. A large number of patients seek alternative or complementary therapies of which diet is an important component. This article reviews the evidence for diet in rheumatoid arthritis along with the associated concept of oral tolerization.

METHODS

References were taken from Medline from 1966 to September 2004. The keywords, rheumatoid arthritis, diet, n-3 fatty acids, vitamins, and oral tolerization, were used.

RESULTS

Randomized controlled trials (RCTs) indicate that dietary supplementation with n-3 fatty acids provides modest symptomatic benefit in groups of patients with rheumatoid arthritis. Epidemiological studies and RCTs show cardiovascular benefits in the broader population and patients with ischemic heart disease. A number of mechanisms through which n-3 fats may reduce inflammation have been identified. In a small number of patients with rheumatoid arthritis, other dietary manipulation such as fasting, vegan, and elimination diets may have some benefit. However, many of these diets are impractical or difficult to sustain long term.

CONCLUSIONS

Dietary manipulation provides a means by which patients can a regain a sense of control over their disease. Dietary n-3 supplementation is practical and can be easily achieved with encapsulated or, less expensively, bottled fish oil.

Assessment of interleukin-12, gamma interferon, and tumor necrosis factor alpha secretion in sera from mice fed with dietary lipids during different stages of Listeria monocytogenes infection

Recent experimental observations have determined that long-chain n-3 polyunsaturated fatty acids suppress immune functions and are involved in the reduction of infectious disease resistance. BALB/c mice were fed for 4 weeks with one of four diets containing either olive oil (OO), fish oil (FO), hydrogenated coconut oil, or a low fat level. Interleukin-12p70 (IL-12p70), gamma interferon (IFN-gamma), and tumor necrosis factor alpha (TNF-alpha) production in the sera of mice fed these diets and challenged with Listeria monocytogenes were determined by enzyme-linked immunosorbent assay. In addition, bacterial counts from spleens of mice were carried out at 24, 72, or 96 h of infection. Here, we quantified an initial diminution of production of both IL-12p70 and IFN-gamma, which appear to play an important role in the reduction of host resistance to L. monocytogenes infection. In addition, an efficient elimination of L. monocytogenes was observed in spleens of mice fed a diet containing OO at 96 h of infection, despite reductions in IL-12p70 and TNF-alpha production, suggesting an improvement of immune resistance. Overall, our results indicate that the initial reduction of both IL-12 and IFN-gamma production before L. monocytogenes infection represents the most relevant event that corroborates the impairment of immune resistance by n-3 polyunsaturated fatty acids during the different stages of infection. However, we speculate that the modulation of other cytokines must be also involved in this response, because the alteration of cytokine production in mice fed an FO diet in a late phase of L. monocytogenes infection was similar to that in mice fed OO, whereas the ability to eliminate this bacterium from the spleen was improved in the latter group.

Fat intake and composition of fatty acids in serum phospholipids in a randomized, controlled, Mediterranean dietary intervention study on patients with rheumatoid arthritis

BACKGROUND

We have previously reported that rheumatoid arthritis patients, who adopted a modified Cretan Mediterranean diet, obtained a reduction in disease activity and an improvement in physical function and vitality. This shift in diet is likely to result in an altered intake of fatty acids. Therefore, the objective of the present study was to examine the dietary intake of fatty acids, as well as the fatty acid profile in serum phospholipids, during the dietary intervention study presented earlier.

RESULTS

From baseline to the end of the study, changes in the reported consumption of various food groups were observed in the Mediterranean diet group. The change in diet resulted in a number of differences between the Mediterranean diet group and the control diet group regarding the fatty acid intake. For instance, a lower ratio of n-6 to n-3 fatty acids was observed in the Mediterranean diet group, both assessed by diet history interviews (dietary intake) and measured in serum phospholipids. Moreover, the patients in the Mediterranean diet group that showed a moderate or better clinical improvement during the study (diet responders), had a higher reported intake of n-3 fatty acids and a lower ratio of n-6 to n-3 fatty acids compared to the patients with minor or no improvement. Also the fatty acid profile in serum phospholipids differed in part between the diet responders and the diet non-responders.

CONCLUSION

The changes in the fatty acid profile, indicated both by dietary assessments and through fatty acids in s-phospholipids may, at least in part, explain the beneficial effects of the Cretan Mediterranean diet that we have presented earlier.

Olive oil and modulation of cell signaling in disease prevention

Epidemiological studies show that populations consuming a predominantly plant-based Mediterranean-style diet exhibit lower incidences of chronic diseases than those eating a northern European or North American diet. This observation has been attributed to the greater consumption of fruits and vegetables and the lower consumption of animal products, particularly fat. Although total fat intake in Mediterranean populations can be higher than in other regions (ca. 40% of calories), the greater proportion is derived from olive oil and not animals. Increased olive oil consumption is implicated in a reduction in cardiovascular disease, rheumatoid arthritis, and, to a lesser extent, a variety of cancers. Olive oil intake also has been shown to modulate immune function, particularly the inflammatory processes associated with the immune system. Olive oil is a nonoxidative dietary component, and the attenuation of the inflammatory process it elicits could explain its beneficial effects on disease risk since oxidative and inflammatory stresses appear to be underlying factors in the etiology of these diseases in man. The antioxidant effects of olive oil are probably due to a combination of its high oleic acid content (low oxidation potential compared with linoleic acid) and its content of a variety of plant antioxidants, particularly oleuropein, hydroxytyrosol, and tyrosol. It is also possible that the high oleic acid content and a proportionate reduction in linoleic acid intake would allow a greater conversion of alpha-linolenic acid (18:3n-3) to longer-chain n-3 PUFA, which have characteristic health benefits. Adoption of a Mediterranean diet could confer health benefits in high-risk populations.

Enzymes for transgenic biosynthesis of long-chain polyunsaturated fatty acids

Polyunsaturated fatty acids (PUFAs) are important for the normal development and function of all organisms, and are essential in maintaining human health. Impaired PUFA metabolism is thought to be associated with pathogenesis of many chronic diseases. Dietary supplementation of PUFAs, such as gamma-linolenic acid, arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid, which bypass the defective or dysfunctional steps of the biosynthetic pathway has been found to significantly alleviate the symptoms of the disease. These findings have drawn a great deal of interest from general public and food manufacturers. As the demand of these beneficial PUFAs has drastically increased in recent years, there are also increasing efforts in finding the alternate sources of PUFAs that are more economical and sustainable. One option is to modify the oil-seed crops to produce PUFAs through genetic engineering technique. This review examines the isolation, identification and expression of genes encoding the enzymes required for the biosynthesis of the above mentioned PUFAs in plants.

A combination of soft-shell turtle powder and essential oil of a unicellular chorophyte prevents bone loss and decreased bone strength in ovariectomized rats

The effects of soft-shell turtle (Trionyx sinensis) powder (SST) on the proximal tibiae of ovariectomized (OVX) rats were investigated using peripheral quantitative computed tomography (pQCT) and examination of serum biochemical markers. Considering the relationship between the antioxidative property and antiosteoporotic activity, the synergistic effects of a mixture of SST and essential oil of the microalgae Haematococcus pluvialis (OHP) with strong antioxidant activity were also examined. Oral administration of SST (100, 200 mg/kg) or a mixture of SST (100, 200 mg/kg) and OHP (13, 26 mg/kg) three times weekly prevented the decrease in bone mineral content (BMC) in total bone, BMC and bone mineral density (BMD) in cortical bone, and bone strength indices induced by ovariectomy in a dose-dependent manner without uterine side effects. However, OHP alone showed no significant effects.

Supplementation of fish oil and olive oil in patients with rheumatoid arthritis

OBJECTIVE

This study evaluated whether supplementation with olive oil could improve clinical and laboratory parameters of disease activity in patients who had rheumatoid arthritis and were using fish oil supplements.

METHODS

Forty-three patients (34 female, 9 male; mean age = 49 +/- 19y) were investigated in a parallel randomized design. Patients were assigned to one of three groups. In addition to their usual medication, the first group (G1) received placebo (soy oil), the second group (G2) received fish oil omega-3 fatty acids (3 g/d), and the third group (G3) received fish oil omega-3 fatty acids (3 g/d) and 9.6 mL of olive oil. Disease activity was measured by clinical and laboratory indicators at the beginning of the study and after 12 and 24 wk. Patients' satisfaction in activities of daily living was also measured.

RESULTS

There was a statistically significant improvement (P < 0.05) in G2 and G3 in relation to G1 with respect to joint pain intensity, right and left handgrip strength after 12 and 24 wk, duration of morning stiffness, onset of fatigue, Ritchie's articular index for pain joints after 24 wk, ability to bend down to pick up clothing from the floor, and getting in and out of a car after 24 wk. G3, but not G2, in relation to G1 showed additional improvements with respect to duration of morning stiffness after 12 wk, patient global assessment after 12 and 24 wk, ability to turn faucets on and off after 24 wk, and rheumatoid factor after 24 wk. In addition, G3 showed a significant improvement in patient global assessment in relation to G2 after 12 wk.

CONCLUSIONS

Ingestion of fish oil omega-3 fatty acids relieved several clinical parameters used in the present study. However, patients showed a more precocious and accentuated improvement when fish oil supplements were used in combination with olive oil.

n-3 PUFAs modulate T-cell activation via protein kinase C-α and -ε and the NF-κB signaling pathway

We elucidated the mechanisms of action of two n-3 PUFAs, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), in Jurkat T-cells. Both DHA and EPA were principally incorporated into phospholipids in the following order: phosphatidylcholine < phosphatidylethanolamine < phosphatidylinositol/phosphatidylserine. Furthermore, two isoforms of phospholipase A(2) (i.e., calcium-dependent and calcium-independent) were implicated in the release of DHA and EPA, respectively, during activation of these cells. The two fatty acids inhibited the phorbol 12-myristate 13-acetate (PMA)-induced plasma membrane translocation of protein kinase C (PKC)-alpha and -epsilon. The two n-3 PUFAs also inhibited the nuclear translocation of nuclear factor kappaB (NF-kappaB) and the transcription of the interleukin-2 (IL-2) gene in PMA-activated Jurkat T-cells. Together, these results demonstrate that DHA and EPA, being released by two isoforms of phospholipase A(2), modulate IL-2 gene expression by exerting their action on two PKC isoforms and NF-kappaB in Jurkat T-cells.

Effects of dietary omega3 and omega6 lipids and vitamin E on proliferative response, lymphoid cell subsets, production of cytokines by spleen cells, and splenic protein levels for cytokines and oncogenes in MRL/MpJ-lpr/lpr mice

omega3 Fatty acid rich fish oil (FO) and vitamin E may delay the progress of certain autoimmune diseases. The present study examined the mechanisms of action of omega3 lipids and vitamin E in autoimmune-prone MRL/lpr mice suffering from extensive lymphoproliferation, lupus-like symptoms, and accelerated aging. To determine whether the effects of omega3 lipids in autoimmune disease is linked to vitamin E levels, weanling female MRL/lpr and congenic control MRL/++ mice were fed diets containing 10% corn oil (CO) or 10% FO at two levels of vitamin E (75 IU or 500 IU/kg diet) for 4 months. The appearance of lymph nodes was delayed in the mice fed FO, and higher levels of FO offered further protection against the appearance of lymph nodes. Analysis of the spleen cells revealed that the cells positive for Thy.1 and Fas were significantly higher in the MRL/++ mice. The groups fed high levels of vitamin E generally exhibited higher levels of Fas. The proliferative response of splenocytes of MRL/++ mice to mitogens was significantly higher compared with MRL/lpr mice. Interleukin (IL)-10 production by spleen cells was significantly higher in FO-fed MRL/lpr mice than in CO-fed mice. In mice fed a high level of vitamin E, the production of IL-12 and tumor necrosis factor-alpha was significantly lower and IL-2 was significantly higher than in animals fed a low level of vitamin E. Proinflammatory cytokines were higher in the MRL/lpr mice and both FO and vitamin E lowered the levels of proinflammatory cytokines and lipid mediators. Western blots revealed that c-myc and c-ras were significantly lower and IL-2 and transforming growth factor (TGF)-beta1 levels were significantly higher in the spleens of MRL/++ mice. FO lowered c-myc and high levels of vitamin E in the diets normalized the levels of TGF-beta1 in MRL/lpr mice. The observations from this study suggest that both FO and vitamin E modulate the levels of specific cytokines, decrease the levels of proinflammatory cytokines, inflammatory lipid mediators, and c-myc, and increase TGF-beta1 levels in spleens of MRL/lpr mice and thus may delay the progress of autoimmune diseases.

Dietary risk factors for rheumatic diseases

PURPOSE OF REVIEW

Recent scientific data illuminate the dietary link to rheumatic disorders. This review summarizes recently published articles on the dietary link to rheumatoid arthritis, gout, and osteoarthritis.

RECENT FINDINGS

A prospective study suggests that higher intakes of meat and total protein as well as lower intakes of fruit, vegetables, and vitamin C are associated with an increased risk of inflammatory polyarthritis or rheumatoid arthritis. Several studies suggest that the Mediterranean-type diet or its main components may have protective effects on the development or severity of rheumatoid arthritis. A recent prospective study investigated several purported dietary factors for gout and confirmed some of the long-standing suspicions (red meats, seafood, beer, and liquor), exonerated others (total protein, wine, and purine-rich vegetables), and also identified potentially new protective factors (dairy products). Recent double-blind, randomized, placebo-controlled studies suggest that antioxidant vitamins (vitamin E, vitamin C, beta-carotene, and retinol) do not halt the progression of symptomatic knee osteoarthritis, as was previously suggested.

SUMMARY

Because diet is an unavoidable universal exposure for people, even a small effect that can be achieved by dietary manipulation may produce a large impact on the population's health. As the evidence on the role of dietary factors in rheumatic disorders grows it becomes increasingly important for clinicians and investigators in the field of rheumatology to familiarize themselves with the relevant data and appropriately apply them to clinical and public health practice.

Changes in the immune functions and susceptibility to Listeria monocytogenes infection in mice fed dietary lipids

The direct examination of the effects that fish oil diets (composed of long-chain n-3 polyunsaturated fatty acids) exert on immune system function indicates a reduction of host natural resistance to infectious diseases mainly because of a suppression of immune function generated by the fatty acids contained in this diet. Here, we evaluated the concentration of IL-12, IL-4, prostaglandin E2 and leukotriene B4 in the serum from BALB/c mice receiving four different diets. Each group was fed a diet that differed only in the source of fat: a low-fat diet (2.5% by weight), an olive oil diet (20% by weight), a fish oil diet (20% by weight) or a hydrogenated coconut oil diet (20% by weight). Mice were fed for 4 weeks and then infected with the intracellular pathogen Listeria monocytogenes. An initial reduction in the Th1-type response as a result of a decrease in IL-12p70 secretion, an inefficient action of IL-4 (Th2-type response) and no modification of pro-inflammatory lipid-mediator production could be, at least in part, the key events responsible for the inadequate elimination of L. monocytogenes from the spleens of mice fed a fish oil diet. Furthermore, our results suggest that the type of dietary lipids may affect the circulating concentration of IL-12p70 and IL-4, leading to a modulation in the protective cellular immune response to L. monocytogenes infection.

Eicosapentaenoic Acid and Docosahexaenoic Acid Reduce UVB- and TNF-α-induced IL-8 Secretion in Keratinocytes and UVB-induced IL-8 in Fibroblasts

Omega-3 polyunsaturated fatty acids (n-3 PUFA) inhibit ultraviolet B (UVB)-induced inflammation and other inflammatory states, in vivo. We examined whether this may be mediated by modulation of interleukin (IL)-8, a chemokine pivotal to skin inflammation induced by UVB, in epidermal and dermal cells. We also explored the ability of n-3 PUFA to protect against tumor necrosis factor (TNF)-alpha induction of IL-8, and assessed relative potencies of the principal dietary n-3 PUFA, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Pre-supplementation, both HaCaT keratinocyte and CCD922SK fibroblast cell lines showed dose-responses for UVB-induced IL-8 release (p<0.001), assessed 48 h post-irradiation. Cells were supplemented with > or =90% purified EPA, DHA, oleic acid (OA) or vehicle control, for 4.5 d. EPA and DHA supplements were bioavailable to keratinocytes and fibroblasts. In keratinocytes, EPA and DHA were shown to reduce basal secretion of IL-8 by 66% and 63%, respectively (p<0.05), and UVB-induced levels by 66% and 65% at 48 h after 100 mJ per cm2, respectively, (p<0.01). A similar pattern occurred in fibroblasts, whereas OA had no influence on IL-8 release in either cell line. In addition, TNF-alpha-induced IL-8 secretion by keratinocytes was reduced by 54% and 42%, respectively, by EPA and DHA (p<0.001). Hence both n-3 PUFA inhibit production of UVB- and TNF-alpha-induced IL-8 in skin cells; this may be important in the photoprotective and other anti-inflammatory effects conferred by these agents.

Omega 3 fatty acids for prevention and treatment of cardiovascular disease

BACKGROUND

It has been suggested that omega 3 (W3, n-3 or omega-3) fats from oily fish and plants are beneficial to health.

OBJECTIVES

To assess whether dietary or supplemental omega 3 fatty acids alter total mortality, cardiovascular events or cancers using both RCT and cohort studies.

SEARCH STRATEGY

Five databases including CENTRAL, MEDLINE and EMBASE were searched to February 2002. No language restrictions were applied. Bibliographies were checked and authors contacted.

SELECTION CRITERIA

RCTs were included where omega 3 intake or advice was randomly allocated and unconfounded, and study duration was at least six months. Cohorts were included where a cohort was followed up for at least six months and omega 3 intake estimated.

DATA COLLECTION AND ANALYSIS

Studies were assessed for inclusion, data extracted and quality assessed independently in duplicate. Random effects meta-analysis was performed separately for RCT and cohort data.

MAIN RESULTS

Forty eight randomised controlled trials (36,913 participants) and 41 cohort analyses were included. Pooled trial results did not show a reduction in the risk of total mortality or combined cardiovascular events in those taking additional omega 3 fats (with significant statistical heterogeneity). Sensitivity analysis, retaining only studies at low risk of bias, reduced heterogeneity and again suggested no significant effect of omega 3 fats. Restricting analysis to trials increasing fish-based omega 3 fats, or those increasing short chain omega 3s, did not suggest significant effects on mortality or cardiovascular events in either group. Subgroup analysis by dietary advice or supplementation, baseline risk of CVD or omega 3 dose suggested no clear effects of these factors on primary outcomes. Neither RCTs nor cohorts suggested increased relative risk of cancers with higher omega 3 intake but estimates were imprecise so a clinically important effect could not be excluded.

REVIEWERS' CONCLUSIONS

It is not clear that dietary or supplemental omega 3 fats alter total mortality, combined cardiovascular events or cancers in people with, or at high risk of, cardiovascular disease or in the general population. There is no evidence we should advise people to stop taking rich sources of omega 3 fats, but further high quality trials are needed to confirm suggestions of a protective effect of omega 3 fats on cardiovascular health. There is no clear evidence that omega 3 fats differ in effectiveness according to fish or plant sources, dietary or supplemental sources, dose or presence of placebo.