Fish oil supplementation and insulin sensitivity: a systematic review and meta-analysis

THREE-YEAR OUTCOMES IN A RANDOMIZED SINGLE-BLIND CONTROLLED TRIAL OF INTRAVITREAL RANIBIZUMAB AND ORAL SUPPLEMENTATION WITH DOCOSAHEXAENOIC ACID AND ANTIOXIDANTS FOR DIABETIC MACULAR EDEMA

The decrease in macular thickness observed at 24 months was maintained at Month 36 in patients with diabetic macular edema treated with a combination of intravitreal ranibizumab and oral supplementation with high-dose docosahexaenoic acid and antioxidants.

Purpose:

To report 3-year results of a randomized single-blind controlled trial of intravitreal ranibizumab combined with oral docosahexaenoic acid (DHA) supplementation versus ranibizumab alone in patients with diabetic macular edema.

Methods:

There were 26 patients (31 eyes) in the DHA group and 29 (38 eyes) in the control group. Ranibizumab (0.5 mg) was administered monthly for the first 4 months followed by a pro re nata (PRN) regimen. In the experimental group, patients received oral DHA supplementation (1,050 mg/day) (Brudyretina 1.5 g).

Results:

At 36 months, mean decrease of central subfield macular thickness was higher in the DHA-supplementation group than in controls (275 ± 50 μm vs. 310 ± 97 μm) with significant differences at Months 25, 30, 33, and 34. Between-group differences in best-corrected visual acuity were not found, but the percentages of ETRDS gains >5 and >10 letters were higher in the DHA-supplementation group. Differences serum HbA1c, plasma total antioxidant capacity values, erythrocyte DHA content, and serum IL-6 levels were all significant in favor of the DHA-supplementation group.

Conclusion:

The addition of a high-rich DHA dietary supplement to intravitreal ranibizumab was effective to achieve better sustained improvement of central subfield macular thickness outcomes after 3 years of follow-up as compared with intravitreal ranibizumab alone.

DHA-enriched fish oil reduces insulin resistance in overweight and obese adults

Adipose tissue inflammation is major factor in the development of insulin resistance (IR). Long-chain omega-3 polyunsaturated fatty acids (LCn-3PUFA) docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are anti-inflammatory bioactive lipids, thus may protect against type 2 diabetes (T2D) development. Previous research has demonstrated a sex-dependent association between LCn-3PUFA and T2D, and evidence suggests LCn-3PUFA may improve IR in a sex-dependent manner. This double-blind, randomized, parallel-arm placebo-controlled study aimed to determine whether DHA-enriched fish oil (FO) supplementation improves IR. Sex-dependent effects were assessed by testing for an interaction between sex and treatment in the multiple regression models. Men and women with abdominal obesity (waist circumference: males, ≥102 cm; females, ≥88 cm) and without diabetes were recruited from the community. Participants (age: 50.9 ± 12.7 years, female: 63.7%, BMI: 32.4 ± 6.6 kg/m²) were randomly allocated to either 2 g FO (860 mg DHA + 120 mg EPA) (intervention, n = 38) or 2 g corn oil (CO) /day (control, n = 35) for 12 weeks in a double-blind randomised controlled trial. A fasting blood sample was collected at 0 and 12 weeks for assessment of IR, glucose and blood lipid profile. Sixty-eight participants completed the intervention. Compared with CO (n = 32), FO (n = 36) significantly reduced fasting insulin by -1.62 μIU/L (95%CI: -2.99, -0.26,) (p = 0.021) and HOMA-IR by -0.40 units (95%CI: -0.78, -0.02, p = 0.038). Higher insulin and HOMA-IR at baseline were associated with greater reductions in the FO group (p < 0.001). There was no interaction between sex and treatment for the change in insulin (p-interaction_{sex*treatment} = 0.816) or HOMA-IR (p-interaction_{sex*treatment} = 0.825). DHA-enriched FO reduces IR in adults with abdominal obesity, however, sex-dependent differences were not evident in this study.

Overview of dietary supplements on patients with type 2 diabetes

BACKGROUND AND AIMS

The primary approach for managing type 2 diabetes mellitus (T2DM) involves lifestyle modification and diet therapy along with pharmacologic interventions. Many patients are interested to identify nutritional supplements that may provide benefit in prevention and management of diabetes. However, the efficacy and safety of nutritional supplements such as chromium, n-3 polyunsaturated fatty acids (PUFAs), vitamin D, zinc and magnesium in disease treatment is a worrying and controversial matter. In this narrative review, patients and health care providers are introduced to the effects of mentioned dietary supplements that may help in choosing or not choosing these supplements in treatment of diabetes.

METHODS

This review was carried out using comprehensive and systematic literature reports on the dietary supplements in the management of diabetes. Empirical searches were conducted using Google Scholar, Science Direct and PubMed databases. Searches were also undertaken using keywords, in English, such as "chromium" OR "vitamin D" OR "omega-3 fatty acids" OR "zinc" OR "magnesium" in combination with "type 2 diabetes".

RESULTS

The available evidence is insufficient to create a definite conclusion that nutritional supplements including chromium, n-3 PUFAs, vitamin D, zinc and magnesium might be beneficial for the prevention and treatment of T2DM and therefore, the general recommendation to use these supplements in the management of diabetes cannot be justified. The results of most studies lack uniformity across multiple aspects, including different dose and formation of supplements, duration, and subjects under intervention.

CONCLUSIONS

There is a need for well-designed, high quality, large and long-term studies to strengthen the available evidence and ensure the safety and efficacy of products.

Biomarkers of fatty acids and risk of type 2 diabetes: a systematic review and meta-analysis of prospective cohort studies

We aimed to quantify and generate comprehensive evidence on the associations of different fatty acids (FAs) with the risk of type 2 diabetes mellitus (T2DM). PubMed, MEDLINE, and Embase were searched for prospective cohort studies that examined the association between FA biomarkers and the risk of T2DM published before 18 May 2020. Random-effects meta-analyses of the effects of FA concentration on T2DM were performed. Thirty-three studies involving 95,810 adults (19,904 cases) were included. Divergent associations of different types of FAs with type 2 diabetes were observed. The pooled relative risk (RRs) of T2DM comparing the top versus the bottom tertile of saturated FAs (C14:0, C16:0, C18:0, total saturated FAs), monounsaturated FA (C16:1 n-7), polyunsaturated FA (C20:3 n-6, C22:4 n-6), and Δ-6-desaturase activities ranged from 1.19 to 1.80. Interestingly, unlike previous studies, we found a negative correlation between odd-chain saturated FAs (C15:0, C17:0), trans-FAs (trans-C16:1 n-7), total n-6, Δ-5-desaturase activities and risk of T2DM. The pooled RRs of T2DM comparing the top versus the bottom tertile of these FAs ranged from 0.62 to 0.78. No associations with T2DM were observed for the other FAs. Considerable heterogeneity was observed in our study, and no definitive conclusions can be made until further investigation has been carried out.

Fish oil supplementation alleviates metabolic and anxiodepressive effects of diet-induced obesity and associated changes in brain lipid composition in mice

OBJECTIVE

Obesity significantly elevates the odds of developing mood disorders. Chronic consumption of a saturated high-fat diet (HFD) elicits anxiodepressive behavior in a manner linked to metabolic dysfunction and neuroinflammation in mice. Dietary omega-3 polyunsaturated fatty acids (n-3 PUFA) can improve both metabolic and mood impairments by relieving inflammation. Despite these findings, the effects of n-3 PUFA supplementation on energy homeostasis, anxiodepressive behavior, brain lipid composition, and gliosis in the diet-induced obese state are unclear.

METHODS

Male C57Bl/6J mice were fed a saturated high-fat diet (HFD) or chow for 20 weeks. During the last 5 weeks mice received daily gavage ("supplementation") of fish oil (FO) enriched with equal amounts of docosahexaenoic (DHA) and eicosapentaenoic acid (EPA) or control corn oil. Food intake and body weight were measured throughout while additional metabolic parameters and anxiety- and despair-like behavior (elevated-plus maze, light-dark box, and forced swim tasks) were evaluated during the final week of supplementation. Forebrain lipid composition and markers of microglia activation and astrogliosis were assessed by gas chromatography-mass spectrometry and real-time PCR, respectively.

RESULTS

Five weeks of FO supplementation corrected glucose intolerance and attenuated hyperphagia in HFD-induced obese mice without affecting adipose mass. FO supplementation also defended against the anxiogenic and depressive-like effects of HFD. Brain lipids, particularly anti-inflammatory PUFA, were diminished by HFD, whereas FO restored levels beyond control values. Gene expression markers of brain reactive gliosis were supressed by FO.

CONCLUSIONS

Supplementing a saturated HFD with FO rich in EPA and DHA corrects glucose intolerance, inhibits food intake, suppresses anxiodepressive behaviors, enhances anti-inflammatory brain lipids, and dampens indices of brain gliosis in obese mice. Together, these findings support increasing dietary n-3 PUFA for the treatment of metabolic and mood disturbances associated with excess fat intake and obesity.

A Mixture of Algae and Extra Virgin Olive Oils Attenuates the Cardiometabolic Alterations Associated with Aging in Male Wistar Rats

Aging is one of the major risk factors for suffering cardiovascular and metabolic diseases. Due to the increase in life expectancy, there is a strong interest in the search for anti-aging strategies to treat and prevent these aging-induced disorders. Both omega 3 polyunsaturated fatty acids (ω-3 PUFA) and extra virgin olive oil (EVOO) exert numerous metabolic and cardiovascular benefits in the elderly. In addition, EVOO constitutes an interesting ingredient to stabilize ω-3 PUFA and decrease their oxidation process due to its high content in antioxidant compounds. ω-3 PUFA are commonly obtained from fish. However, more ecological and sustainable sources, such as algae oil (AO) can also be used. In this study, we aimed to study the possible beneficial effect of an oil mixture composed by EVOO (75%) and AO (25%) rich in ω-3 PUFA (35% docosahexaenoic acid (DHA) and 20% eicosapentaenoic acid (EPA)) on the cardiometabolic alterations associated with aging. For this purpose; young (three months old) and old (24 months old) male Wistar rats were treated with vehicle or with the oil mixture (2.5 mL/kg) for 21 days. Treatment with the oil mixture prevented the aging-induced increase in the serum levels of saturated fatty acids (SFA) and the aging-induced decrease in the serum concentrations of mono-unsaturated fatty acids (MUFA). Old treated rats showed increased serum concentrations of EPA and DHA and decreased HOMA-IR index and circulating levels of total cholesterol, insulin and IL-6. Treatment with the oil mixture increased the mRNA levels of antioxidant and insulin sensitivity-related enzymes, as well as reduced the gene expression of pro-inflammatory markers in the liver and in cardiac and aortic tissues. In addition, the treatment also prevented the aging-induced endothelial dysfunction and vascular insulin resistance through activation of the PI3K/Akt pathway. Moreover, aortic rings from old rats treated with the oil mixture showed a decreased response to the vasoconstrictor AngII. In conclusion, treatment with a mixture of EVOO and AO improves the lipid profile, insulin sensitivity and vascular function in aged rats and decreases aging-induced inflammation and oxidative stress in the liver, and in the cardiovascular system. Thus, it could be an interesting strategy to deal with cardiometabolic alterations associated with aging.

Docosahexaenoic Acid-Rich Fish Oil Supplementation Reduces Kinase Associated with Insulin Resistance in Overweight and Obese Midlife Adults

Targeting kinases linked to insulin resistance (IR) and inflammation may help in reducing the risk of type 2 diabetes (T2D) and Alzheimer’s disease (AD) in its early stages. This study aimed to determine whether DHA-rich fish oil supplementation reduces glycogen synthase kinase (GSK-3), which is linked to both IR and AD. Baseline and post-intervention plasma samples from 58 adults with abdominal obesity (Age: 51.7 ± 1.7 years, BMI: 31.9 ± 0.8 kg/m²) were analysed for outcome measures. Participants were allocated to 2 g DHA-rich fish oil capsules (860 mg DHA + 120 mg EPA) (n = 31) or placebo capsules (n = 27) per day for 12 weeks. Compared to placebo, DHA-rich fish oil significantly reduced GSK-3β by −2.3 ± 0.3 ng/mL. An inverse correlation (p < 0.05) was found between baseline insulin and IR and their changes following intervention only in participants with C-reactive protein levels higher than 2.4 mg/L. DHA-rich fish oil reduces GSK-3 and IR, suggesting a potential role of long-chain omega-3 polyunsaturated fatty acids (LCn-3PUFA) in ameliorating AD risk.

Nutritional Strategies to Offset Disuse-Induced Skeletal Muscle Atrophy and Anabolic Resistance in Older Adults: From Whole-Foods to Isolated Ingredients

Preserving skeletal muscle mass and functional capacity is essential for healthy ageing. Transient periods of disuse and/or inactivity in combination with sub-optimal dietary intake have been shown to accelerate the age-related loss of muscle mass and strength, predisposing to disability and metabolic disease. Mechanisms underlying disuse and/or inactivity-related muscle deterioration in the older adults, whilst multifaceted, ultimately manifest in an imbalance between rates of muscle protein synthesis and breakdown, resulting in net muscle loss. To date, the most potent intervention to mitigate disuse-induced muscle deterioration is mechanical loading in the form of resistance exercise. However, the feasibility of older individuals performing resistance exercise during disuse and inactivity has been questioned, particularly as illness and injury may affect adherence and safety, as well as accessibility to appropriate equipment and physical therapists. Therefore, optimising nutritional intake during disuse events, through the introduction of protein-rich whole-foods, isolated proteins and nutrient compounds with purported pro-anabolic and anti-catabolic properties could offset impairments in muscle protein turnover and, ultimately, the degree of muscle atrophy and recovery upon re-ambulation. The current review therefore aims to provide an overview of nutritional countermeasures to disuse atrophy and anabolic resistance in older individuals.

Fish consumption and the risk of cardiovascular disease and mortality in patients with type 2 diabetes: a dose-response meta-analysis of prospective cohort studies

We aimed to investigate the association of fish consumption with the risk of coronary heart disease (CHD), stroke and all-cause mortality in patients with type 2 diabetes (T2D). We systematically searched PubMed and Scopus from inception till June 2019. We included prospective cohort studies assessing the relation of fish intake with the risk of CHD, stroke and mortality in patients with T2D. Study-specific results were pooled with the use of a random-effects model. Nine prospective cohort studies with 57,394 diabetic patients were identified. The relative risks for the highest compared with the lowest category of fish consumption were 0.86 (95% CI 0.76, 0.96; I² = 50%, n = 8) for all-cause mortality, and 0.61 (95% CI 0.29, 0.93; I² = 68%, n = 3) for CHD. There was a monotonic inverse association, with a nadir at fish consumption of approximately 2-3 servings/week, in both analyses. A nonsignificant inverse association was found for stroke. In the analysis of all-cause mortality, a nonsignificant inverse association was found in studies that controlled for energy intake, suggesting that the observed inverse association was not an addition effect, but may be due to substituting other foods such as red and processed meat with fish.

Effects of fish oil supplementation on glucose control and lipid levels among patients with type 2 diabetes mellitus: a Meta-analysis of randomized controlled trials

BACKGROUND

Previous studies have yielded inconsistent findings on the role of fish oil in type 2 diabetes mellitus (T2DM). We systematically summarized the available evidence from randomized controlled trials (RCT) and aimed to investigate the effects of fish oil supplementation on glucose control and lipid levels among patients with T2DM.

METHODS

A comprehensive literature search was performed in electronic databases (PubMed, ProQuest, Cochrane Library, CNKI, VIP, and Wanfang) to identify all relevant RCTs which were published up to May 31st, 2019. We used Modified Jadad Score system to evaluate the quality of each included RCT. The pooled effects were estimated using random-effects model and presented as standardized mean differences with 95% confidence intervals.

RESULTS

A total of 12 RCTs were included in this meta-analysis. There was no significant difference in glucose control outcomes comparing fish oil supplementation to placebo. The effect size of fasting plasma glucose (FPG) was 0.13 (95% CI: - 0.03 to 0.28, p > 0.05). No marked change was observed in fasting insulin (FINS), glycosylated hemoglobin (HbA1c), and HOMA of insulin resistance (HOMA-IR) levels. Fish oil supplementation was associated with a decrease of triglyceride (TG) level by - 0.40 (95%CI: - 0.53 to - 0.28, p < 0.05), and an increase of high density lipoprotein (HDL) cholesterol level by 0.21 (95%CI: 0.05 to 0.37, p < 0.05). In subgroup analysis, HDL cholesterol level was higher among Asian and low-dose(< 2 g/d n-3 PUFA) subgroups compared to their counterparts (p < 0.05). TG level was lower in mid and long duration groups, along with an inconspicuous difference in short duration group.

CONCLUSIONS

This meta-analysis shows that among patients with T2DM, fish oil supplementation leads to a favorable blood lipids profile but does not improve glucose control.

Fish oil reduces subclinical inflammation, insulin resistance, and atherogenic factors in overweight/obese type 2 diabetes mellitus patients: A pre-post pilot study

OBJECTIVE

Insulin resistance-associated obesity and type 2 diabetes mellitus (T2DM) are commonly accompanied with metabolic lipid abnormalities and are characterized by hypertriglyceridemia and low HDL-c levels (atherogenic index plasma, AIP). The primary molecular mechanism that is known to cause insulin resistance is chronic low-grade inflammation. Considering that omega-3 fatty acid reduces subclinical inflammation, we hypothesized that fish oil could affect insulin resistance and AIP. Therefore, the present study evaluated the effects of fish oil supplementation on the inflammatory, insulin resistance, and atherogenic factors in overweight/obese T2DM patients.

RESEARCH DESIGNS AND METHODS

In this study, we recruited 32 overweight and/or obese patients diagnosed with T2DM for over one year and who exhibited hypertriglyceridemia. These patients received fish oil supplementation (4.0 g/day) for eight weeks. Anthropometric and body composition measurements were obtained. In addition, blood samples were collected before and after omega-3 supplementation for the evaluation of lipid profile, glycemia, insulin, and inflammation.

RESULTS

As expected, patients showed reduction in the TNFα, IL-1β, and Il-6 levels after fish oil supplementation and showed improved insulin sensitivity (HOMA-IR) without observed alterations in anthropometric and body composition. These observations were followed by reduction in the levels of triglycerides and non-esterified fatty acids, increase in HDL cholesterol levels, and a significant reduction in triglycerides/HDL-c ratio, and total cholesterol/HDL-c ratio.

CONCLUSION

Fish oil supplementation is effective in reducing the levels of proinflammatory cytokines, improving insulin resistance, and reducing atherogenic factors in overweight/obese and T2DM patients independent of weight loss.

Fish oil supplementation and maintaining muscle mass in chronic disease: state of the evidence

PURPOSE OF REVIEW

Providing eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), in the form of fish oils, to benefit muscle is an emerging area of interest. The aim of this work was to evaluate the current literature that has assessed muscle mass as an outcome during a fish oil intervention in any chronic disease.

RECENT FINDINGS

The vast majority of studies published in the last 3 years (12 of 15) have been conducted in the oncological setting, in patients undergoing treatment for cancers of the gastrointestinal tract, breast, head and neck, lung, cervix, and hematological cancers. Three studies were conducted in patients with chronic obstructive pulmonary disease (COPD). Fish oil was provided as part of nutrient mixtures in 12 studies and as capsules in three studies.

SUMMARY

Overall, the evidence for an effect of fish oil supplementation on muscle mass in patients with cancer undergoing treatment and in COPD remains unequivocal and reveals limited new knowledge in the area of fish oil supplementation in the cancer setting. Recent literature continues to provide mixed evidence on the efficacy of fish oil on muscle mass and function. The present review highlights challenges in comparing and interpreting current studies aimed at testing fish oil supplementation for muscle health.

Are marine n-3 fatty acids protective towards insulin resistance? From cell to human

Marine n-3 fatty acids improve most of the biochemical alterations associated with insulin resistance (IR). Experimental models of dietary-induced IR in rodents have shown their ability (often at a very high dose) to prevent IR, but with sometimes a tissue specific effect. However, in a high sucrose diet-induced IR rat model, they are unable to reverse IR once installed; in other rodent models (dexamethasone, Zucker rats), they are inefficacious perhaps because of the severity of IR. The very low incidence of type-2 diabetes (T2D) in Inuits in the 1960s, which largely increased over the following decades in parallel to the replacement of their traditional marine food for a western diet strongly suggests a protective effect of marine n-3 towards the risk of T2D; this was confirmed by reversal of its incidence in intervention studies reintroducing their traditional food. In healthy subjects and insulin-resistant non-diabetic patients, most trials and meta-analyses conclude to an insulin-sensitising effect and to a very probable preventive or alleviating effect towards IR. Concerning the risk of T2D, concordant data allow us to conclude the protective effect of marine n-3 in Asians while suspicion exists of an aggravation of risk in Westerners, but with the possibility that it could be explained by a high heterogeneity of studies performed in this population. Some longitudinal cohorts in US/European people showed no association or a decreased risk. Further studies using more homogeneous doses, sources of n-3 and assessment of insulin sensitivity methods are required to better delineate their effects in Westerners.

Diets with lower carbohydrate concentrations improve insulin sensitivity in women with polycystic ovary syndrome: A meta-analysis

OBJECTIVE

Women with polycystic ovary syndrome (PCOS) are associated with increased levels of insulin resistance (IR). Other than treatment with insulin-sensitizing drugs, specialized diets have also been implemented to reduce the patient's IR. However, the capacity of certain diets, concerning with the severity of the patient's IR, to improve insulin sensitivity has not fully been explored. Therefore, we conducted a meta-analysis to determine in PCOS subjects from low to severe IR, if hypocaloric diets improve insulin sensitivity.

STUDY DESIGN

PubMed, SCOPUS, EBSCO, and LILACS databases and retrieved studies' bibliographies were searched for prospective studies that investigated the association between diets and IR in PCOS women until October 2018. Diet was defined as a modification of the patients' nutrition intake according to caloric restriction, change in protein intake, or by using a specialized diet. IR measures (HOMA1-IR), pre- and post-intervention were extracted. Using Comprehensive Meta-Analysis software, depending on the level heterogeneity, determined by the ψ²-based Q-test and the I²-test, fixed-effects or random-effects models were used to calculate the pooled standard paired differences (SPD) and 95 %CI.

RESULTS

20 publications (25 studies) fulfilled the inclusion criteria. Due to the heterogeneity of the diets, the random-effects model was used. In 48 % of the studies, the diets led to a decrease of IR, where 44 % had no effect. In 2 studies, the diets increased IR. Overall, the diets decreased IR (SPD=-0.58; 95 %CI: -0.81 to -0.36). Subjects with severe IR (HOMA1-IR>4.2) had a marked improvement (SPD=-1.22; 95 %CI: -1.61 to -0.84). Moreover, diets low in carbohydrate (<50 %) was also determined to improve IR (SPD=-0.86; 95 %CI: -1.23 to -0.50).

CONCLUSIONS

Here, we demonstrate that diets are more likely to improve IR in PCOS women with severe IR. Therefore, it is crucial to determine a subject's IR status before considering any intervention containing a diet.

Is There Something Fishy About Fish Oil?

BACKGROUND

Fish is consumed as food worldwide and is considered as a rich source of essential nutrients required for a healthy life. Supplementation with fish oil has been adopted as a solution to prevent or cure many pathophysiological states and diseases by both the professionals and the civil population. The beneficial effects are, however, being questioned, as some controversial results were obtained in clinical and population studies.

METHODS

Critical evaluation of studies regarding known effects of fish oil, both in favour of its consumption and related controversies.

RESULTS

From the literature review, contradictory allegations about the positive action of the fish oil on human health emerged, so that a clear line about its beneficial effect cannot be withdrawn.

CONCLUSION

Scientific results on the application of fish oil should be taken with caution as there is still no standardised approach in testing its effects and there are significantly different baselines in respect to nutritional and other lifestyle habits of different populations.

The effect of co supplementation of omega-3 and vitamin D on cardio metabolic risk factors and psychological distress in reproductive-aged women with prediabetes and hypovitaminosis D: a study protocol for a randomized controlled trial

BACKGROUND

A prediabetic state is a risk factor for type 2 diabetes. There are no approved drugs to manage prediabetes. Among the supplements routinely used by individuals, vitamin D and omega-3 have been studied to reduce fasting blood sugar. However, their co-supplementation has not been studied in individuals with prediabetes. This randomized controlled trial is designed to determine the effects of these two supplements on fasting blood sugar, other cardio metabolic risk factors, and psychological distress in reproductive-aged women with prediabetes and hypovitaminosis D.

METHODS/DESIGN

This 2 × 2 factorial, triple-blind, randomized, placebo-controlled, clinical trial will be done on 168 women of reproductive age diagnosed with prediabetes and hypovitaminosis D. Participants will be randomly assigned equally to four groups: (1) 1000 mg omega-3 fatty acid twice a day + vitamin D placebo every two weeks; (2) omega-3 fatty acid placebo twice a day + 50,000 IU vitamin D every two weeks; (3) 1000 mg omega-3 fatty acid twice a day + 50,000 IU vitamin D every two weeks; (4) omega-3 fatty acid placebo twice a day + vitamin D placebo every two weeks for eight weeks. At the beginning, participants will provide a self-reported questionnaire on the sociodemographic characteristics. At baseline and post-intervention visits, physical activity, Depression Anxiety Stress Scale 21 and Pittsburgh Sleep Quality Index, and a three-day food record will be collected for each individual. Blood pressure, weight, height, and waist circumference will also be measured. At the beginning and at the end, a blood sample will be used for estimating serum glucose indices (fasting blood sugar and insulin, homeostasis model assessment-insulin resistance, homeostasis model assessment-beta cell function), lipids (triglyceride, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, total cholesterol), and vitamin D status. Data analysis using Kolmogorov-Smirnov test, paired t-test, one-way analysis of variance, and repeated measures analysis of variance will be conducted through SPSS-24 software.

DISCUSSION

The primary aim of the present trial is to determine the effect of vitamin D and/or omega-3 on glycemic indices, lipid profiles, psychological distress, blood pressure, and anthropometric indices in prediabetic women with hypovitaminosis D. The results from this trial will provide evidence on the efficacy of these two supplements for preventing or delaying the onset of type 2 diabetes in high-risk individuals.

TRIAL REGISTRATION

Iran Clinical Trials Registry, IRCT20100130003226N17. Registered on 9 February 2019.

Icosabutate Exerts Beneficial Effects Upon Insulin Sensitivity, Hepatic Inflammation, Lipotoxicity, and Fibrosis in Mice

Icosabutate is a structurally engineered eicosapentaenoic acid derivative under development for nonalcoholic steatohepatitis (NASH). In this study, we investigated the absorption and distribution properties of icosabutate in relation to liver targeting and used rodents to evaluate the effects of icosabutate on glucose metabolism, insulin resistance, as well as hepatic steatosis, inflammation, lipotoxicity, and fibrosis. The absorption, tissue distribution, and excretion of icosabutate was investigated in rats along with its effects in mouse models of insulin resistance (ob/ob) and metabolic inflammation/NASH (high‐fat/cholesterol‐fed APOE*3Leiden.CETP mice) and efficacy was compared with synthetic peroxisome proliferator‐activated receptor α (PPAR‐α) (fenofibrate) and/or PPAR‐γ/(α) (pioglitazone and rosiglitazone) agonists. Icosabutate was absorbed almost entirely through the portal vein, resulting in rapid hepatic accumulation. Icosabutate demonstrated potent insulin‐sensitizing effects in ob/ob mice, and unlike fenofibrate or pioglitazone, it significantly reduced plasma alanine aminotransferase. In high‐fat/cholesterol‐fed APOE*3Leiden.CETP mice, icosabutate, but not rosiglitazone, reduced microvesicular steatosis and hepatocellular hypertrophy. Although both rosiglitazone and icosabutate reduced hepatic inflammation, only icosabutate elicited antifibrotic effects in association with decreased hepatic concentrations of multiple lipotoxic lipid species and an oxidative stress marker. Hepatic gene‐expression analysis confirmed the changes in lipid metabolism, inflammatory and fibrogenic response, and energy metabolism, and revealed the involved upstream regulators. In conclusion, icosabutate selectively targets the liver through the portal vein and demonstrates broad beneficial effects following insulin sensitivity, hepatic microvesicular steatosis, inflammation, lipotoxicity, oxidative stress, and fibrosis. Icosabutate therefore offers a promising approach to the treatment of both dysregulated glucose/lipid metabolism and inflammatory disorders of the liver, including NASH.

Immuno-Resolving Ability of Resolvins, Protectins, and Maresins Derived from Omega-3 Fatty Acids in Metabolic Syndrome

Omega-3 fatty acid consumption has been suggested to be beneficial for the prevention of type 2 diabetes mellitus (T2DM). Its effects have been attributed to anti-inflammatory activity, with the inhibition of arachidonic acid metabolism playing a central role. However, a more recent view is that omega-3 fatty acids play an active role as the precursors of potent, specialized pro-resolving mediators (SPMs), such as resolvins, protectins, and maresins. Docosahexaenoic acid (DHA)- and eicosapentaenoic-acid-derived SPMs are identified in the adipose tissue but the levels of certain SPMs (e.g., protectin D1) are markedly reduced with obesity, suggesting adipose SPM deficiency, potentially resulting in unresolved inflammation. Supplementation of the biosynthetic intermediates of SPM (e.g., 17-hydroxy-DHA) or omega-3 fatty acids increases the level of adipose SPMs, reduces adipose inflammation (decrease in macrophage accumulation and change to less inflammatory macrophages), and enhances insulin sensitivity. The findings from studies using rodent obesity models must be translated to humans. It will be important to further elucidate the underlying mechanisms by which obesity reduces the levels of and the sensitivity to SPM in adipose tissues. This will enable the development of nutrition therapy to enhance the effects of omega-3 fatty acids in the prevention and/or treatment of T2DM.

Blood biomarkers of various dietary patterns correlated with metabolic indicators in Taiwanese type 2 diabetes

Background

Metabolic alterations correlate with adverse outcomes in type 2 diabetes. Dietary modification serves as an integral part in its treatment.

Objective

We examined the relationships among dietary patterns, dietary biomarkers, and metabolic indicators in type 2 diabetes (n = 871).

Design

Diabetic patients (n = 871) who provided complete clinical and dietary data in both 2008 and 2009 were selected from a cohort participating in a diabetic control study in Taiwan. Dietary data were obtained using a short, semiquantitative food frequency questionnaires, and dietary pattern identified by factor analysis. Multiple linear regressions were used to analyze the association between dietary biomarkers (ferritin, folate, and erythrocyte n-3 polyunsaturated fatty acids [n-3 PUFAs]) and metabolic control upon adjusting for confounders.

Results

Three dietary patterns (high-fat meat, traditional Chinese food–snack, and fish–vegetable) were identified. Ferritin correlated positively with high-fat meat factor scores (P for trend <0.001). Erythrocyte n-3 PUFAs (eicosapentaenoic acid [EPA] + docosahexaenoic acid [DHA], n-3/n-6 PUFA ratio) correlated positively with fish–vegetable factor scores (all P for trends <0.001). Multiple linear regressions revealed a positive relationship between ferritin concentrations and fasting plasma glucose (FPG), hemoglobin A1c (HbA1c), and triglycerides, but a negative relationship with high-density lipoprotein cholesterol (HDL-C). Erythrocyte n-3 PUFA, EPA+DHA, and n-3/n-6 PUFA ratio were negatively linked to FPG, HbA1c, and triglycerides (all P < 0.05) and positively with HDL-C (though n-3/n-6 ratio marginally correlated).

Conclusions

Ferritin and n-3 PUFA can serve as valid biomarkers for high-fat meat and fish–vegetable dietary patterns. Unlike ferritin, erythrocyte n-3 PUFA status was related to better glycemic and blood lipid profiles. Our results suggest that habitual consumption of diet pattern rich in fish and vegetables may contribute in part to a healthier metabolic profile in type 2 diabetes.

Effects of oily fish intake on cardiometabolic markers in healthy 8- to 9-y-old children: the FiSK Junior randomized trial

BACKGROUND

Fish oil improves cardiometabolic markers in adults, but results in children are inconsistent. Few children meet the recommended fish intake and no randomized trials have investigated how fish intake per se affects children's cardiometabolic profile.

OBJECTIVE

We investigated whether oily fish consumption modulated serum triacylglycerol and diastolic blood pressure (coprimary outcomes) and other cardiometabolic markers in healthy Danish children and whether effects were sex-specific.

METHODS

In a randomized controlled 12-wk trial, 199 children (aged 8-9 y) received ∼300 g/wk of oily fish or poultry (control). We measured blood pressure, heart rate, and heart rate variability (HRV) via 3-h continuous electrocardiograms and collected fasting blood samples for analysis of erythrocyte EPA [20:5n-3 (ω-3)] + DHA (22:6n-3) and serum triacylglycerol, LDL and HDL cholesterol, glucose, and insulin.

RESULTS

One hundred and ninety-seven children (99%) completed the trial. The fish group consumed a median (IQR) of 375 (325-426) g oily fish/wk and the poultry group consumed 400 (359-452) g poultry/wk, which resulted in 2.25 (95% CI: 1.88, 2.62) fatty acid percentage-point higher erythrocyte EPA + DHA in the fish group (P < 0.001). In the fish group, serum triacylglycerol decreased by 0.05 mmol/L (95% CI: 0.00, 0.11 mmol/L) (P = 0.04) and HDL cholesterol increased by 0.07 mmol/L (95% CI: 0.01, 0.13 mmol/L) (P = 0.02); the triacylglycerol effect showed dose-dependency with erythrocyte EPA + DHA (r = -0.15, P = 0.04), whereas HDL showed a tendency for such an association(r = 0.13, P = 0.08). Additional analyses indicated sex-specificity (Pdiet*sex < 0.10), because triacylglycerol was reduced by 0.09 mmol/L (95% CI: 0.02, 0.16 mmol/L) in boys only (girls: -0.00; 95% CI: -0.07, 0.07 mmol/L) and heart rate was reduced by 3.4 bpm (95% CI: 0.2, 6.6 bpm) in girls only (boys: 0.6; 95% CI: -2.6, 3.8 bpm). Blood pressure, HRV, and glucose homeostasis were unaffected.

CONCLUSIONS

Oily fish intake improved serum triacylglycerol and HDL cholesterol in a dose-dependent manner in 8- to 9-y-old children, but had no effect on blood pressure, HRV, or glucose homeostasis. This supports recommendations for fish intake in children and underlines the importance of initiatives to increase children's intake of oily fish. This trial was registered at clinicaltrials.gov as NCT02809508.

Omega-3 Fatty Acids Activate Ciliary FFAR4 to Control Adipogenesis

Adult mesenchymal stem cells, including preadipocytes, possess a cellular sensory organelle called the primary cilium. Ciliated preadipocytes abundantly populate perivascular compartments in fat and are activated by a high-fat diet. Here, we sought to understand whether preadipocytes use their cilia to sense and respond to external cues to remodel white adipose tissue. Abolishing preadipocyte cilia in mice severely impairs white adipose tissue expansion. We discover that TULP3-dependent ciliary localization of the omega-3 fatty acid receptor FFAR4/GPR120 promotes adipogenesis. FFAR4 agonists and ω-3 fatty acids, but not saturated fatty acids, trigger mitosis and adipogenesis by rapidly activating cAMP production inside cilia. Ciliary cAMP activates EPAC signaling, CTCF-dependent chromatin remodeling, and transcriptional activation of PPARγ and CEBPα to initiate adipogenesis. We propose that dietary ω-3 fatty acids selectively drive expansion of adipocyte numbers to produce new fat cells and store saturated fatty acids, enabling homeostasis of healthy fat tissue.

Dietary habits, metabolic health and vitamin D status in Greenlandic children

OBJECTIVE

To compare the dietary habits of children living in northern villages and in the capital of Greenland, given the reported transition from traditional to westernised diet in adults over recent decades, and to explore the association between consumption of marine mammals and fish (MMF) and the children's metabolic profile and vitamin D status.

DESIGN

Children answered an FFQ encompassing sixty-four individual food types pooled into six food categories. Their pubertal stage, body fat, fitness level, metabolic profile (non-HDL-cholesterol, glycated Hb, insulin, glucose, high-sensitivity C-reactive protein) as well as serum 25-hydroxyvitamin D (25(OH)D) concentration were evaluated.

SETTING

Siorapaluk and Qaanaaq (north of Greenland) and Nuuk (west).

PARTICIPANTS

Children aged 6-18 years (n 177).

RESULTS

MMF were most frequently eaten by children from Siorapaluk (mean (sd): 73·4 (14·1) times/month), followed by children from Qaanaaq (37·0 (25·0) times/month), and least often eaten by children from Nuuk (23·7 (24·6) times/month; P < 0·001). Children from Qaanaaq consumed 'junk food' more frequently (P < 0·001) and fruits and vegetables less frequently (P < 0·01) than children from Nuuk. MMF consumption was positively associated with serum 25(OH)D concentration (P < 0·05), but the overall prevalence of vitamin D deficiency was high (18 %). No association was found between MMF consumption and metabolic parameters.

CONCLUSIONS

The dietary transition and influence of western diets have spread to the north of Greenland and only the most remote place consumed a traditional diet highly based on MMF. We found no strong associations of MMF consumption with metabolic health, but a positive association with vitamin D status.

Changes in Plasma Free Fatty Acids Associated with Type-2 Diabetes

Type 2 diabetes mellitus (T2DM) is associated with increased total plasma free fatty acid (FFA) concentrations and an elevated risk of cardiovascular disease. The exact mechanisms by which the plasma FFA profile of subjects with T2DM changes is unclear, but it is thought that dietary fats and changes to lipid metabolism are likely to contribute. Therefore, establishing the changes in concentrations of specific FFAs in an individual’s plasma is important. Each type of FFA has different effects on physiological processes, including the regulation of lipolysis and lipogenesis in adipose tissue, inflammation, endocrine signalling and the composition and properties of cellular membranes. Alterations in such processes due to altered plasma FFA concentrations/profiles can potentially result in the development of insulin resistance and coagulatory defects. Finally, fibrates and statins, lipid-regulating drugs prescribed to subjects with T2DM, are also thought to exert part of their beneficial effects by impacting on plasma FFA concentrations. Thus, it is also interesting to consider their effects on the concentration of FFAs in plasma. Collectively, we review how FFAs are altered in T2DM and explore the likely downstream physiological and pathological implications of such changes.

Nutraceutical targeting of TLR4 signaling has potential for prevention of cancer cachexia

The mechanisms underlying cancer cachexia - the proximate cause of at least 20% of cancer-related deaths - have until recently remained rather obscure. New research, however, clarifies that cancers evoking cachexia release microvesicles rich in heat shock proteins 70 and 90, and that these extracellular heat shock proteins induce cachexia by serving as agonists for toll-like receptor 4 (TLR4) in skeletal muscle, macrophages, and adipocytes. Hence, safe nutraceutical measures which can down-regulate TLR4 signaling can be expected to aid prevention and control of cancer cachexia. There is reason to suspect that phycocyanobilin, ferulic acid, glycine, long-chain omega-3s, green tea catechins, β-hydroxy-β-methylbutyrate, carnitine, and high-dose biotin may have some utility in this regard.

Effect of low-ratio n-6/n-3 PUFA on blood glucose: a meta-analysis

OBJECTIVE

The aim of this meta-analysis was to investigate the effect of increasing dietary low-ratio n-6/n-3 polyunsaturated fatty acid (PUFA) intake on blood glucose and other related indicators.

METHODS

We systematically searched randomized controlled trials of low-ratio n-6/n-3 PUFA intervention on PubMed, Embase, Cochrane library and related references up to August 2018. The change values were calculated as the weighted mean difference (WMD) by using a random-effect model.

RESULTS

Eleven randomized controlled trials were included. No significant effect of dietary low-ratio n-6/n-3 PUFA supplementation was observed on fasting blood glucose (WMD: 0.057 mmol L^-1; 95% CI: -0.090 to 0.204 mmol L^-1), insulin (WMD: -0.757 mIU L^-1; 95% CI: -2.419 to 0.904 mIU L^-1), insulin resistance index (WMD: -0.201; 95% CI: -0.566 to 0.165), and glycosylated hemoglobin (WMD: -0.063%; 95% CI: -0.061 to 0.186%). Subgroup analysis showed that the effect of low-ratio n-6/n-3 PUFA on the reduction of the plasma insulin level in North America (WMD: -3.473 mIU L^-1; 95% CI: -5.760 to -1.185 mIU L^-1) was more obvious than that in Asian countries (WMD: -0.797 mIU L^-1; 95% CI: -2.497 to 0.902 mIU L^-1) and European countries (WMD: -0.063 mIU L^-1; 95% CI: -0.061 to 0.186 mIU L^-1). In the subgroup of diabetic subjects, low-ratio n-6/n-3 PUFA supplementation can decrease the plasma insulin level (WMD: -3.010 mIU L^-1; 95% CI: -5.371 to -0.648 mIU L^-1) and insulin resistance index (WMD: -0.460; 95% CI: -0.908 to -0.012). When the intervention period was longer than 8 weeks, low-ratio n-6/n-3 PUFA supplementation could also decrease the plasma insulin level (WMD: -2.782 mIU L^-1; 95% CI: -4.946 to -0.618 mIU L^-1). No significant publication bias was observed for all blood glucose and other related indicators as suggested by Begg's test and Egger's test.

CONCLUSION

Our meta-analysis found that low-ratio n-6/n-3 PUFA supplementation could improve the glucose metabolism by reducing the insulin and insulin resistance in the diabetic patients. Low-ratio n-6/n-3 PUFA supplementation could reduce the plasma insulin level when the supplementation duration was longer than 8 weeks.

Oxidative stress pathways in pancreatic β-cells and insulin-sensitive cells and tissues: importance to cell metabolism, function, and dysfunction

It is now accepted that nutrient abundance in the blood, especially glucose, leads to the generation of reactive oxygen species (ROS), ultimately leading to increased oxidative stress in a variety of tissues. In the absence of an appropriate compensatory response from antioxidant mechanisms, the cell, or indeed the tissue, becomes overwhelmed by oxidative stress, leading to the activation of intracellular stress-associated pathways. Activation of the same or similar pathways also appears to play a role in mediating insulin resistance, impaired insulin secretion, and late diabetic complications. The ability of antioxidants to protect against the oxidative stress induced by hyperglycemia and elevated free fatty acid (FFA) levels in vitro suggests a causative role of oxidative stress in mediating the latter clinical conditions. In this review, we describe common biochemical processes associated with oxidative stress driven by hyperglycemia and/or elevated FFA and the resulting clinical outcomes: β-cell dysfunction and peripheral tissue insulin resistance.

A randomized control trial of the impact of LCPUFA-ω3 supplementation on body weight and insulin resistance in pubertal children with obesity

BACKGROUND

Paediatric obesity and insulin resistance (IR) are potentially reversible inflammatory conditions. Long chain polyunsaturated fatty acids omega-3 (LCPUFA-ω3) show anti-inflammatory and metabolic properties, but their clinical efficacy is unclear.

OBJECTIVE

The objective of this study is to evaluate whether supplementation with LCPUFA-ω3 for 3 months reduces insulin resistance and weight to adolescents with obesity.

METHODS

Double-blind trial of 366 adolescents with obesity randomly assigned to 1.2-g LCPUFA-ω3 (DO3) or 1-g sunflower oil (DP) daily for 3 months; both groups received an energy-restricted diet. Children attended monthly for anthropometric, dietary, and clinical measurements. Basal and final blood samples were obtained to measure metabolic markers and erythrocytes fatty acids. Regression models were used for analysis.

RESULTS

A total of 119 DO3 and 126 DP children completed follow-up. At baseline, 92% of children presented IR, 66% hypertriglyceridemia, 37% low-grade inflammation, and 32% metabolic syndrome. Despite erythrocytes LCPUFA-ω3 increased more in DO3 (Median differences = 0.984 w/w%; 95 IC = 0.47, 1.53, P < 0.001), body weight, insulin, and HOMA changed similarly in both groups at the end of intervention. Adjusting for basal values, changes in weight, insulin, and HOMA was not related with supplementation.

CONCLUSIONS

Supplementation with LCPUFA-ω3 does not affect body weight or insulin in adolescents with obesity.

Fatty acids: a role for Africa?

Health effects of fatty acids have been very controversial. Total mortality is inversely associated with the amount of total fat consumed. In contrast,transfatty acids or SFA intake is positively related to mortality while the inverse is observed with consumption of MUFA or PUFA. Among PUFA, long-chain (LC)n-3 PUFA have many beneficial effects. Dietary intake of some types of fatty acids is specific to Africa. Energy from saturated fat does not exceed 14% and energy fromn-6 PUFA does not exceed 8% of total energy intake. Dietary intake of LCn-3 PUFA is less than 100 mg/d whereas international recommendations promote 250–500 mg/d. Consumption of plantn-3 PUFA mainly α-linolenic acid (ALA) is highly variable depending on the country. Both fish and ALA availability are low in several African countries. The prevalence of diabetes and cardiovascular events remain very low in Africa, partly explained by the fact that the whole dietary pattern is globally the best of all continents. One objective of ‘fat for Africa’ could be to increase, as much as possible, the dietary intake of LCn-3 PUFA by promoting sustainable aquaculture and to maintain as much as possible traditional dietary pattern by preventing a tendency to westernisation, provided that the amount of energy and protein is sufficient to fight against wasting and stunting where it still exists.

Curcumin and/or omega-3 polyunsaturated fatty acids supplementation reduces insulin resistance and blood lipids in individuals with high risk of type 2 diabetes: a randomised controlled trial

Background

Lowering insulin resistance and dyslipidaemia may not only enhance glycaemic control but also preserve the β-cell function, reducing the overall risk of developing type 2 diabetes (T2D). The current study was aimed to evaluate the effects of curcumin and/or long-chain omega-3 polyunsaturated fatty acids (LCn-3PUFA) supplementation on glycaemic control and blood lipid levels in individuals at high risk of developing T2D.

Methods

This was a 2 × 2 factorial, randomised, double-blinded, placebo-controlled study. Participants were allocated to either double placebo (PL) or curcumin plus placebo matching for LCn-3PUFA (CC), or LCn-3PUFA plus placebo matching for curcumin (FO), or curcumin plus LCn-3PUFA (CC-FO) for twelve weeks. Primary outcome of the trial was glycaemic indices (HbA1C, fasting glucose and insulin). Insulin resistance and sensitivity is measured using homeostatic model assessment model.

Results

A total of sixty-four participants (PL, n = 16; CC, n = 15; FO, n = 17, CC-FO, n = 16) were included in the final analysis. Post-intervention, HbA1c and fasting glucose remained unchanged across all the groups. Insulin sensitivity was significantly improved in the CC supplemented group (32.7 ± 10.3%) compared to PL (P = 0.009). FO and CC-FO tended to improve insulin sensitivity by 14.6 ± 8.5% and 8.8 ± 7.7% respectively, but the difference did not reach significance. Triglyceride levels were further increased in the PL (26.9 ± 7.4%), however, CC and CC-FO supplementation reduced the triglycerides, FO resulted in the greatest reduction in triglycerides (− 16.4 ± 4.5%, P < 0.001).

Conclusion

Reduction in insulin resistance and triglycerides by curcumin and LCn-3PUFA appears to be attractive strategies for lowering the risk of developing T2D. However, this study failed to demonstrate complimentary benefits of curcumin and LCn-3PUFA on glycaemic control.

Trail registration

ACTRN12615000559516.

Electronic supplementary material

The online version of this article (10.1186/s12944-019-0967-x) contains supplementary material, which is available to authorized users.

Effects of n-3 fatty acid supplements on cardiometabolic profiles in hypertensive patients with abdominal obesity in Inner Mongolia: a randomized controlled trial

Daily supplementation with n-3 fatty acid (FA) has been believed to be an adjunct or alternative to drug treatments to reduce blood pressure (BP) and triglyceride (TG) levels in western patients with high risk of cardiovascular disease.

Curcumin alleviates postprandial glycaemic response in healthy subjects: A cross-over, randomized controlled study

In the current study, we aimed to evaluate the effects of a single dose of curcumin and/or fish oil on postprandial glycaemic parameters in healthy individuals. This was a randomised, placebo-controlled and crossover study. Sixteen (n = 16) volunteers were randomised to receive placebo, curcumin (180 mg) tablets, fish oil (1.2 g long chain omega-3 polyunsaturated fatty acids) capsules and curcumin + fish oil prior to a standard meal on 4 test days separated by a week. Blood glucose, serum insulin and triglycerides were measured at intervals between 0–120 min. Difference between the treatments was measured using two-way repeated measures analysis of variance and pair-wise comparisons using Wilcoxon signed-rank or paired t-test as appropriate. Postprandial glucose concentrations were significantly lower in the curcumin (60.6%, P = 0.0007) and curcumin + fishoil group (51%, P = 0.002) groups at 60 min from baseline. Compared with placebo, area under the curve (AUC) for change in blood glucose concentration was reduced by curcumin (36%, P = 0.003) and curcumin + fishoil (30%, 0.004), but not fish oil alone (p = 0.105). Both curcumin (P = 0.01) and curcumin + fishoil (P = 0.03) treatments significantly lowered postprandial insulin (AUC) by 26% in comparison with placebo. Curcumin, but not fish oil, reduces postprandial glycaemic response and insulin demand for glucose control.

Cosmetic and Therapeutic Applications of Fish Oil's Fatty Acids on the Skin

Fish oil has been broadly reported as a potential supplement to ameliorate the severity of some skin disorders such as photoaging, skin cancer, allergy, dermatitis, cutaneous wounds, and melanogenesis. There has been increasing interest in the relationship of fish oil with skin protection and homeostasis, especially with respect to the omega-3 polyunsaturated fatty acids (PUFAs), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA). The other PUFAs, such as α-linolenic acid (ALA) and linoleic acid (LA), also show a beneficial effect on the skin. The major mechanisms of PUFAs for attenuating cutaneous inflammation are the competition with the inflammatory arachidonic acid and the inhibition of proinflammatory eicosanoid production. On the other hand, PUFAs in fish oil can be the regulators that affect the synthesis and activity of cytokines for promoting wound healing. A systemic review was conducted to demonstrate the association between fish oil supplementation and the benefits to the skin. The following describes the different cosmetic and therapeutic approaches using fatty acids derived from fish oil, especially ALA, LA, DHA, and EPA. This review summarizes the cutaneous application of fish oil and the related fatty acids in the cell-based, animal-based, and clinical models. The research data relating to fish oil treatment of skin disorders suggest a way forward for generating advances in cosmetic and dermatological uses.

Linoleic acid, glycemic control and Type 2 diabetes

Dietary fat quality, especially the intake of specific types of fatty acids, impacts the risk of many chronic diseases, including cardiovascular diseases, certain cancers and type 2 diabetes (T2DM). A recent pooled analysis involving 20 studies from around the world revealed that higher linoleic acid (18:2n-6 LA) biomarker is associated with dose-dependent decreases in the incidence of T2DM. This latest study corroborates earlier cross-sectional studies and intervention trials showing that biomarkers of LA intake are associated with reduced risk of T2DM and better glycemic control and/or insulin sensitivity. This review highlights key clinical trials that have evaluated the role of LA in glycemia and the related condition, insulin sensitivity.

Dietary Fatty Acids Differentially Regulate Secretion of Adiponectin and Interleukin-6 in Primary Canine Adipose Tissue Culture

The aim of this study was to determine the effect of n3 polyunsaturated fatty acids (PUFA) on canine adipose tissue secretion of adiponectin, interleukin-6 (IL6), and tumor necrosis factor-α (TNFα). Subcutaneous and omental visceral adipose tissue samples were collected from 16 healthy intact female dogs. Concentrations of adiponectin were measured in mature adipocyte cultures, and concentrations of IL6 and TNFα were measured in undifferentiated stromovascular cell (SVC) cultures following treatment with eicosapentaenic acid (EPA, 20:5n-3), arachidonic acid (ARA, 20:4n-6), or palmitic acid (PAM, 16:0) at 25, 50, or 100 μM. Secretion of adiponectin from mature adipocytes was higher (p < 0.001) following EPA treatment at 50 μM compared to control in subcutaneous tissue, and higher following EPA treatment compared to PAM treatment at 25 μM in both subcutaneous (p < 0.001) and visceral tissues (p = 0.010). Secretion of IL6 from SVC derived from subcutaneous tissue was lower following EPA treatment and higher following PAM treatment compared to control both at 50 μM (p = 0.001 and p = 0.041, respectively) and 100 μM (p = 0.013 and p < 0.001, respectively). These findings of stimulation of adiponectin secretion and inhibition of IL6 secretion by EPA, and stimulation of IL6 secretion by PAM, are consistent with findings of increased circulating concentrations of adiponectin and decreased circulating concentration of IL6 in dogs supplemented with dietary fish oil, and show that the effect of fish oil on circulating concentrations of adiponectin and IL6 is, at least partially, the result of local effects of EPA and PAM on adipose tissue.

Omega-3 Fatty Acid Supplementation Improves Heart Rate Variability in Obese Children

Obese children and adolescents are at high risk of developing cardiovascular diseases later in life. We hypothesized that cardiovascular prophylaxis with omega-3 fatty acids could benefit them. In our study, 20 children and adolescents (mean body mass index percentile: 99.1; mean age: 11.0 years) underwent two ambulatory 24 h Holter electrocardiography (ECG) recordings (before and after at least 3 months of omega-3 fatty acid supplementation). Time domain heart rate variability (HRV) and heart rate (HR) were examined for these patients. As a control, we used 24 h Holter ECG recordings of 94 nonobese children and adolescents. Time domain HRV parameters, which are indicators of vagal stimulation, were significantly lower in obese patients than in healthy controls, but HR was higher (standard deviation of the normal-to-normal [SDNN] interbeat intervals: −34.02%; root mean square of successive differences [RMSSD] between normal heartbeats: −40.66%; percentage of consecutive RR intervals [pNN50]: −60.24%; HR: +13.37%). After omega-3 fatty acid supplementation, time domain HRV parameters and HR of obese patients were similar to the values of healthy controls (SDNN interbeat intervals: −21.73%; RMSSD: −19.56%; pNN50: −25.59%; HR: +3.94%). Therefore, omega-3 fatty acid supplementation may be used for cardiovascular prophylaxis in obese children and adolescents.