Today’s Dietitian
Vol. 27 No. 8 P. 40
Take this course and earn 2 CEUs on our Continuing Education Learning Library
Metabolic syndrome (MetS) is a collection of disorders that include abdominal obesity, hypertension (HTN), dyslipidemia including high triglycerides (TGs) and/or low HDL cholesterol, and impaired glucose metabolism (elevated fasting blood glucose).1-4 It’s generally accepted that MetS can be diagnosed with three of the five conditions listed above and is a condition that continues to increase in US adults while also presenting a clinical burden to the health care system.2,5,6 The National Health and Nutrition Examination Survey 2003–2004 to 2013–2014 data showed that frequency and prevalence of MetS affected about 50 million people in the United States during that time.6
MetS is a syndrome often accompanied by low-grade, systemic inflammation and increased inflammatory markers such as C-reactive protein (CRP) due to increased and chronic generation of reactive oxygen species. Other chronic conditions such as nonalcoholic steatohepatitis, and insulin resistance and/or type 2 diabetes (DMII) often accompany the syndrome.7 Because of the evidence that MetS is inflammatory in nature, omega-3 (n-3) fatty acids are an area of interest for dietary intervention and management. Previous literature has shown benefits of n-3 intake or status in a variety of improved patient outcomes.8 However, results of n-3s and their role in MetS are inconsistent and need more exploration regarding dosing standardization, differences in genetics and n-3 metabolism, and the generalizability of recommendations.4,9
In a large study by Hirode et al (n=17,048), the prevalence of MetS has increased from 33% in previous studies to 34.7% between 2011 and 2016. Therefore, examining nutrition interventions to improve conditions within MetS is critical for public health.3,10 RDs play a vital role on the interdisciplinary care team to help prevent, treat, and manage chronic MetS and other inflammatory conditions.
This continuing education course provides an overview of how dietary and supplemental sources of n-3 fatty acids influence both inflammatory markers for people with MetS as well as their health outcomes. It specifically explores the role of the RD and how to educate on n-3 intake in patients with MetS.
Dietary Fat, Inflammation, and MetS
Evidence shows that the standard Western diet is rich in omega-6 (n-6) polyunsaturated fatty acids (PUFAs) while n-3 fatty acids are underrepresented when compared with current the Healthy Eating Index (HEI).11 This dietary imbalance may worsen the pathogenesis of disease within the MetS diagnosis such as cardiovascular outcomes, DMII, and nonalcoholic steatohepatitis because of the linoleic acid to arachidonic acid cascade leading to enhanced inflammatory pathways.1,2 Because of the promising effects of n-3 intake observed in people with diseases within a MetS diagnosis, more research is indicated to observe whether dosing n-3 could be effective, what dosing is beneficial, the ratio of EPA to DHA needed, and who this intervention could help the most regarding age, ethnicity, lifestyle, sex, genetics, etc.9
Omega-3s and Inflammation
Many studies indicate a connection between chronic, systemic inflammation and the clinical risks of MetS including CVD and DMII as they relate to dietary fat intake. When examining studies for how n-3 intake may influence inflammatory markers and outcomes in adults with MetS, findings showed positive outcomes for participants with MetS, DMII, and out-of-range cardiometabolic lab markers. A meta-analysis and meta-regression of 45 randomized controlled trials (n=2,674) in adults with DMII by O’Mahoney et al found that n-3 supplementation was associated with significantly lower LDL and VLDL, TGs, hemoglobin A1c levels, and reductions in inflammatory markers tumor necrosis factor alpha (TNF-a) and interleukin 6 (IL-6).12 The researchers cite a need for more studies to help identify the independent effects of DHA and EPA.
Similar to the O’Mahoney et al study, in an 8.8-year prospective study of 2,754 participants, researchers Ding et al found that adults with MetS who had higher n-3 erythrocyte status experienced lower risk of HTN, and higher risk of low HDL and high TGs.4 Researchers discussed conflicting results in regard to PUFA status and glycemic control as well as abdominal obesity. They found that their results were consistent (n-3 status was not associated with changes in body weight or waist circumference) with another large cohort study (n=29,152) but was contrary to another cross-sectional study (n=226) showing those with higher waist circumference had lower n-3 status.13,14
The meta-analysis by Jang and Park (n=13 studies/36,542 participants) concluded that participants with higher intakes of n-3s had a lower risk of MetS. Higher DHA levels connected with lower risk of MetS were particularly important in this study as many studies cite limitations in understanding the different roles and potential dosing between DHA and EPA. This study showed improvements in participants with an n-3 intervention especially in regard to blood lipids, blood glucose, and blood pressure.3
The smaller Shearer et al study aimed to identify how lipoprotein oxylipins (from LDL and HDL) are different between “optimally healthy” controls and participants with MetS. In this study, “optimally healthy” participants were defined as individuals who met strict cardiometabolic criteria including TG <130 mg/dL, TG/HDL ratio <3, BMI between 21 and 25, and no use of lipid-lowering or vasoactive medications in order to establish a rigorously screened control group for comparison with the MetS cohort. They concluded that n-3 therapy produced beneficial changes in LDL and HDL levels in their participants. Because lipoproteins have overlapping actions with inflammation, the researchers suggest that n-3 status could support cardiovascular health by improving endothelial function and could even slow the development of atherosclerosis. The authors noted that the study was not long enough to fully assess this as atherosclerosis develops over a period of time.2
Omega-3 fatty acids have the potential to modify cardiometabolic markers including reducing TG levels.3-5,9,15 Researchers have found that n-3s can reduce TG levels by 20% to 30% when given in therapeutic doses.2 For example, in the hallmark Japan EPA Lipid Intervention Study trial, 18,645 participants with MetS who took 1.8g/d EPA experienced a 50% reduced relative risk for coronary events.15
In their mechanistic update review on n-3s and MetS, researchers Albracht-Schulte et al presented beneficial proposed mechanisms that included modulating lipid metabolism, reducing inflammation in adipose tissue, and regulating adipokines.5 Because obesity, especially central adiposity, is a hallmark of MetS, these mechanisms and their effect on fat cells specifically could be clinically significant and warrant future research.
In a study of adolescents aged 10 to 19 years old, a review of the literature (n=15 studies) by Turek et al found that while studies are mixed regarding n-3 interventions for this population, there were some positive outcomes in blood pressure, glycemic control, reduced TG levels, and increased HDL levels, though not all were conclusive or statistically significant.16
Because inflammation is a hallmark of MetS and can aggravate the conditions associated with it, the available research on interventions can help guide what to do with these patients. While studies are mixed, they have shown that supplementing with n-3s or improving n-3 status in the blood may have beneficial effects and could be a safe addition to people struggling with inflammation or other cardiovascular risk factors.
Dietary Patterns and Omega-3 Recommendations for MetS
Studies have shown promising outcomes for reducing risk of and treating both MetS and inflammation with several dietary patterns including the HEI, the DASH diet, the Mediterranean diet (MedD), and vegetarian/vegan plant-based patterns. These researched eating patterns share many similar applications. They are commonly used in the prevention and treatment of cardiometabolic disease and support reductions in inflammation with a focus on whole, unprocessed foods, fruits, vegetables, whole grains, lean proteins, and reduced intake of high saturated fat meats and added sugar foods. They also each have recommendations for adding n-3s in a way that supports the benefits of the overall dietary pattern. Charles-Messance et al hypothesized that the reason these dietary interventions work is that they reduce metaflammation, a process which can be driven by dietary intake of saturated fats and added sugar consumption, especially from highly processed foods.17 All of these diets promote lessening these inflammatory foods while also including n-3s as a component, which explain why these patterns have been shown to reduce chronic inflammation in the body, playing an important role for people with MetS.
Healthy Eating Index
The HEI, developed by the USDA in order to measure adherence to the Dietary Guidelines for Americans (DGAs) has shown that, if followed, this pattern can reduce MetS risk through dietary strategies such as limiting saturated fat intake to <10% total calories per day and an emphasis on high fiber fruit, vegetable, and whole grain consumption.18 Adherence to the DGAs has been inversely associated with waist circumference, blood pressure, blood glucose, TGs, and LDL cholesterol.18
In a cross-sectional analysis of middle-aged to older adults, (n=1,989) diet quality as determined by the HEI (2015) found that higher diet quality was associated with lower CRP and IL-6 inflammatory markers.19 Their data specifically found that consumption of fruits, vegetables, and legumes may be particularly impactful.19
In the six-month Food4Me study (n=1,380) assessing adults recruited from seven European Union countries, validated food frequency questionnaires were used to analyze dietary patterns’ influence on markers of metabolic health, including the omega-3 index (O3I). The researchers found participants who had higher diet quality scores had lower BMI, lower waist-to-height ratio and waist circumference, and higher carotenoids and O3I scores.20 Those with higher diet quality scores had higher intakes of PUFAs, n-3s, fiber, and folate. It appears that following the HEI may be associated with higher n-3 intake.20
The DGAs and Healthy Plate model can play a role in basic education for any patient with MetS and/or systemic inflammation as a simple model of how to eat and an overarching dietary pattern that supports healthy cardiometabolic factors. RDs can further educate their clients about how to increase n-3 food sources within the HEI pattern.
Dietary Approaches to Stop Hypertension
The DASH diet promotes fruit, vegetables, whole grains, fish, and other lean protein intake, and is low in sodium (2,300 mg), added sugar, and saturated fat intake. Studies show that the greater the adherence to a DASH diet, the lower the prevalence of MetS, especially for markers such as LDL cholesterol and blood pressure.18,21 The DASH diet has also been shown to reduce BMI and waist circumference significantly in many studies.21 Researchers hypothesize that the reason the DASH diet is associated with positive outcomes for cardiovascular risk is due to the inclusion of high fiber foods that are high in micronutrients such as potassium and magnesium and are excellent sources of antioxidants and polyphenols. The diet also limits saturated fat and processed foods.21
A small eight-week randomized controlled trial (n=39) studied elderly female participants with MetS following a DASH diet and included 1 g of n-3 supplementation daily. They observed a reduction in oxidative stress (p<0.001) and decreased LDL (p=0.023) after the intervention.22 Another small 12-week randomized controlled trial (n=33) investigated participants with DMII who followed a DASH diet for 12 weeks. The intervention group (n=17) took 1,000 mg n-3 daily while the control group received a placebo. The researchers saw significantly lower body weight, BMI, blood pressure, and inflammatory markers IL-6 and TNF-a in both groups and significantly decreased TG and VLDL cholesterol levels in the intervention group compared with the control group (p<0.05). Supplementation of n-3, usually dosed at about 1 g per day EPA/DHA, within a DASH diet, appears in several studies to benefit people with MetS and/or blood sugar dysregulation.
RDs can educate on ways to obtain n-3 fatty acids through foods on the DASH diet including following the American Heart Association recommendations to consume a minimum of two servings (3 oz portion) of fish per week such as anchovies, herring, mackerel, black cod, salmon, sardines, bluefin tuna, whitefish, striped bass, and cobia.23 Studies have suggested that n-3 supplementation may have a synergistic beneficial effect for people with MetS who follow the DASH diet.22
Mediterranean Diet
The MedD has long been associated with positive cardiovascular outcomes. For this reason, it may be a helpful dietary approach for preventing and treating MetS.18,24 Studies have shown that adherence to the MedD (35% to 45% calories from fat, 35% to 45% from carbohydrates, and 14% to 18% calories from protein, in many studies) can reduce CVD incidence, lower blood pressure, improve hyperlipidemia, and decrease the incidence of DMII.21,24 It also shows the greatest promise for reducing inflammatory markers including CRP, IL-6, and IL-1 beta in a review and meta-analysis of 22 randomized control trials.25
A small pilot study of ethnically diverse women (n=25) measured inflammatory and endothelial health factors such as nuclear factor kappa B, oxidative stress, and endothelial nitric oxide synthase and found that improvements in cardiovascular risk markers were seen in those with higher plant-based protein (legumes) and lower red and processed meat intake.26 Another study of adolescent girls 13 to 18 years old with MetS found that an intervention of 12 weeks (n=70) of MedD vs food pyramid education saw lower body weight, BMI, waist circumference, systolic blood pressure, fasting blood glucose, TGs, LDL, homeostatic model assessment of insulin resistance, inflammatory markers IL-6 and CRP, and increased HDL in the intervention group. The researchers did not observe a significant effect on decreasing inflammatory marker TNF-a.27
Studies have shown that higher adherence to the MedD tends to promote higher n-3 levels in tissues. In a systematic review of observational and intervention studies (n=28 studies), participants following the MedD demonstrated higher n-3 levels in the body.24 This is likely due to the emphasis on healthy fats in the diet, including extra virgin olive oil, seafood (providing EPA and DHA), and nuts (providing alpha-linolenic acid [ALA]). Researchers have concluded that a MedD is likely higher in n-3 PUFAs than a typical Western diet.24 The authors cite that while most studies reported increased n-3 status, some studies (n=5) did not see a positive correlation between MedD adherence and n-3 status. There are many factors that could be confounding for these results, including differences in habitual baseline diet among the studies. Though some results are mixed, it appears that generally, n-3 intake on the MedD is enhanced over a standard Western dietary pattern and could be part of the benefit to people with MetS.
Plant-Based Diets
Plant-based diets, including vegetarian and vegan diets, have been associated with positive cardiometabolic outcomes, including a lower risk of developing MetS in general as well as each of its individual diagnostic components.21 Plant-based dietary patterns are generally lower in saturated fat and higher in fiber as well as other nutrients that have been positively associated with reduced MetS risk such as vitamins C and E, beta-carotene, and polyphenols.7,21 A cross-sectional study by Navarro et al (n=88) found that people following an omnivorous diet had six times higher odds of developing MetS than people following a vegetarian diet.7,28 Plant-based diets typically include sources of n-3, although they come as ALA, which then must be converted in the body to EPA and DHA. Conversion rates may be minimal. Common plant-based sources of ALA include walnuts, flaxseeds, chia seeds, and soy.29
The type of plant-based diet a patient follows could make a difference. A large prospective cohort study (eight years, n=5,646) done in South Korea by Kim and colleagues found that participants in the highest vs lowest quintile of “unhealthful plant-based diet index,” which included more refined grains, potatoes, sugar-sweetened beverages, sweets, and salty foods, had a 50% higher risk of developing MetS.30 The researchers concluded that plant-based diets with an emphasis on whole grains, fruits, vegetables, nuts, legumes, and tea experienced lower incidence of MetS. This mirrors the research and dietary patterns of a plant-based diet as well as the MedD and HEI.
A cross-sectional study done on 240 adult women (aged 18 to 48 years) with overweight and obesity by Bolori et al found that a healthy plant-based diet, defined by whole grains, fruit, vegetables, cereal, and tea, had significantly lower CRP and transforming growth factor beta inflammatory markers. The researchers hypothesize that adhering to a healthy version of a plant-based diet could help lower inflammation and body weight because of the higher fiber, antioxidants unsaturated fatty acids, and micronutrient content while limiting saturated fat and iron. Notably, though these women were overweight or obese, participants were excluded if they had DMII, CVD, polycystic ovarian syndrome, nonalcoholic fatty liver disease, HTN, cancer, or thyroid disease. Consequently, the true connection between MetS specifically in this study may not be able to be fully elucidated based on the exclusion criteria.31
Research has been done on the effects of ALA on lipids and other cardiometabolic biomarkers in plant-based diets. There is evidence that ALA is not always successfully converted into EPA and DHA. If plant-based sources are the only n-3 consumed on a vegan or vegetarian diet, it’s hard to understand whether it’s the n-3 content or the general healthfulness of the diet creating positive effects for those with MetS.29 A review by Santos, Price, and Bueno in Nutrients found that plant sources of ALA are associated in many studies with positive cardiometabolic changes but also recommends that both increasing ALA food intake as well as considering EPA/DHA supplementation could help further improve n-3 to n-6 ratios in plant-based diets.29 A scoping review on the bioavailability and conversion rates of plant-based n-3s by Lane et al found that while supplementing with ALA sources did not effectively increase blood n-3 status in studies reviewed, microalgae supplements rich in EPA and DHA were effective. These researchers advised that a supplemental source of EPA and DHA may be the most effective way to increase n-3 status in people who do not consume fish.32
Clinicians have many possible recommendations for dietary patterns that exhibit positive effects for MetS and can personalize their advice for each patient’s individual preferences and cultural needs. Dietitians can educate their patients on the many types of plant-based dietary patterns, assessing which is the most appropriate based on preferences, culture, cooking skills, and taste. Emphasis should be placed on plant-based whole foods including vegetables and fruits, high fiber whole grains, and plant-based proteins like nuts, beans, and legumes. Many studies do include lean proteins and omega-3 rich options like poultry and fish. Other heart healthy fats like olive oil, nuts, seeds, and avocado appear to be part of a beneficial dietary pattern as well. RDs can also help their vegan and vegetarian patients assess whether a plant-based algae supplement may be appropriate for a more direct dose of EPA and DHA n-3.
Clinical Guidelines for Omega-3 Fatty Acids in MetS Patients
Studies use a variety of dosing for n-3s in people with MetS and/or systemic inflammation. To correct LDL and HDL dysregulation in people with MetS, researchers Shearer et al used 4 g/day n-3 supplementation and saw significant improvements in the proinflammatory activity of TGs, HDL, LDL, and apolipoprotein B lipoproteins.2 The older Japan EPA Lipid Intervention Study trial used 1.8 g/day of EPA and saw a 50% reduction in relative risk for major coronary events in adults with MetS.15
Both EPA and DHA are also used individually to target a variety of health outcomes. Natural Medicines Database states that 4 g/day EPA is used to reduce TG levels. For other conditions, including cardiovascular, 1 to 2 g/day is used in studies for up to six months.33 DHA is dosed to help target TGs, and also LDL cholesterol and LDL particle size, though studies are mixed, with some showing increases in LDL.34 Natural Medicine’s Database states that doses are typically 400 to 800 mg for up to six months.
In children, studies have ranged from 900 mg/day to 1.8g/d and up to 3,360 mg/day of EPA and DHA for up to six months.35 Because there are no clear clinical guidelines regarding which diet or how much EPA vs DHA (or combination thereof) to provide for MetS and inflammation, dietitians should take an individualized approach with each patient and work with the interdisciplinary care team to assess what dosing may be best. A general range of 1 to 4 g/d in adults and 900 to 3,300 mg in children has been used in recent studies. Keep in mind that there are some drug/nutrient interactions with n-3s, so other supplements, especially those that thin the blood, and medications such as warfarin or other blood-thinning medications should be taken into account when dosing.33,34
Additionally, O3I may need to be taken into consideration to identify if patients can achieve a health-promoting status through food alone or if supplements may be indicated to achieve recommended levels. Some research has shown that an O3I, which is an indicator of EPA and DHA as a percentage of erythrocyte total fatty acids, should be in a range of 8% to 12% for cardiovascular and brain health.36 Researchers Jackson et al assessed two cross-sectional studies that compared O3I levels to fish intake. One study (n=28) used a validated triple-pass 24-hour dietary recall survey and a single fish-intake question. The second study (n=3,458) analyzed data from adults who self-tested O3I levels and answered questions about both their fish intake as well as use of n-3 supplements. Both studies showed that for every increase in reported fish consumption, O3I increased by 0.50% to 0.65% (p < 0.0001) with the best O3I percentages in groups with the highest intake (three or more servings of fish per week).36 This study concluded that the American Heart Association recommendations to consume fish twice per week is likely not enough intake to achieve optimal O3I status. For reference, there is approximately 1.80 g and 1 g of EPA and DHA in Atlantic salmon and Atlantic mackerel, respectively.37 Achieving study doses of 4 g per day with diet alone may not be realistic for some people.
Quality of Studies and Study Limitations
There has been extensive research done on the topic of MetS. However, when examining the role of inflammatory pathways, many studies are based on mice and rat models.1 Other limitations in the current literature include the need for a better understanding of the optimal n-3 supplemental dose in adults, teens, and children with MetS.1
Confounding variables listed in a review by Dos Santos and Fleming on a decade (2010 to 2020) of research on inflammatory markers in DMII and MetS include age, health status, n-3 dose and standardization, duration, and supplements vs diet interventions.1 A prospective cohort study by Ding et al noted limitations including the potential for false statistical significance and lack of ability to differentiate in studies between the potential benefits of EPA and DHA.4 Jang and Park and Ding et al also cite a lack of generalizability because study participants were located in specific countries, therefore the outcomes may be more heavily weighted to those populations.3,4 Several studies including Shearer et al, Jang and Park, and Ding et al state a limitation of the timing of intervention because many of the MetS outcomes and markers take years to develop.2-4
There are still ambiguities in the literature about the exact role of n-3s for people with MetS, including appropriate intake, how long to see results, and exactly how MetS and the various disease states within that diagnosis are affected or improved by reducing inflammatory markers. However, it seems clear that there is promising research on new relationships between n-3s, reducing inflammatory markers, and improving other cardiometabolic factors for the population.
Putting It Into Practice
In practice, RDs play a critical role on the interdisciplinary team when it comes to patients with MetS who also struggle with chronic inflammation. Dietitians can use the available evidence to work with patients who have MetS to assess the balance of n-3 and n-6 fatty acids in the diet and work with the interdisciplinary team to suggest that inflammatory markers such as CRP, TNF-a, and/or IL-6 are drawn and tracked over time. They can use the available research to suggest that clients with MetS supplement with therapeutic doses of n-3 (studies show benefit ranging from 1,800 mg to 4,000 mg) in an effort to improve outcomes in an evidence-based way.2,9
The position of the Academy of Nutrition and Dietetics is that the expertise of RDs and nutrition and dietetics technicians, registered are needed for safe and appropriate selection and guidance of supplements.38 Nutrition professionals should consider always assessing inflammation, n-3 status, and dietary supplements for MetS patients.
RDs can also educate on ways to obtain n-3 fatty acids through foods including following the American Heart Association recommendations to consume two servings of fish per week for those who eat seafood, or from plant-based sources for those who do not.23 They can also cite studies that demonstrate supplementing with n-3 fatty acids can be helpful and work with the patient and their medical team on appropriate product choice (fish-based vs algae-based) and dosing.
It appears that simple adjustments to n-3 intake may make a difference to the health of people with MetS. Evidence appears to indicate that n-3s can help with some or all the conditions associated with MetS, so this should be a consideration when assessing a patient’s diet. RDs can cite evidence that dietary interventions can reduce inflammation and can make the case for dietary supplements, when it appears needed, based on the available literature. Dietitians are uniquely suited to educate and support people with MetS and inflammation.
— Ginger Hultin, DCN, RDN, CSO, is a Seattle-based integrative oncology nutrition specialist and owner of the private practice Ginger Hultin Nutrition, PLLC.
Learning Objectives
After completing this continuing education course, nutrition professionals should be better able to:
1. Describe how omega-3 intake influences inflammatory markers in people with metabolic syndrome.
2. Identify omega-3 foods and supplement dosing that affect inflammation and health outcomes in people with metabolic syndrome.
3. Counsel clients on dietary strategies to reduce inflammation to prevent or reduce the complications of metabolic syndrome.
Examination
1. What are the primary disorders included in metabolic syndrome (MetS)?
a. CVD including low HDL and type 2 diabetes
b. Abdominal obesity, hypertension, dyslipidemia, and impaired glucose metabolism
c. Nonalcoholic steatohepatitis, insulin sensitivity, and high hip to waist circumference
d. Elevated C-reactive protein, reactive oxygen species, and tumor necrosis factor alpha serum levels
2. According to the National Health and Nutrition Examination Survey data, approximately how many people in the United States were affected by MetS during the period from 2004 to 2014?
a. 5 million people
b. 10 million people
c. 25 million people
d. 50 million people
3. Omega-3 fatty acids are an area of interest for dietary intervention in MetS due to their potential:
a. Role in increasing inflammation and reducing blood glucose levels
b. Negative impact on blood glucose levels and hypercholesterolemia
c. Effect on decreasing body weight and waist circumference
d. Anti-inflammatory effects and potential to modify cardiometabolic markers
4. The Healthy Eating Index and the DASH diet are dietary patterns that have shown promising outcomes for reducing the risk of MetS. What do these dietary patterns have in common?
a. Low consumption of processed foods and limits on sodium
b. Moderate intake of fruits and vegetables and high intake of nuts and seeds
c. Emphasis on unprocessed foods, fruits, vegetables, whole grains, and lean proteins
d. Low intake of saturated fat, added sugar, and sodium
5. Which dietary pattern showed the greatest promise for reducing inflammatory markers in a meta-analysis review of randomized control trials by Koelman et al?
a. Vegetarian
b. Mediterranean
c. DASH
d. Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND)
6. Which of the following conditions is not included in the collection of disorders that make up MetS?
a. Abdominal obesity
b. Hypertension
c. High triglycerides
d. High CRP
7. How many of the five listed conditions are generally accepted as necessary for the diagnosis of MetS?
a. One
b. Two
c. Three
d. Four
8. Which dietary pattern has shown promising outcomes in reducing risk factors and treating both MetS and inflammation?
a. Vegetarian diet
b. High-protein diet
c. MIND diet
d. Intermittent fasting
9. Based on the information provided, which of the following statements regarding the Mediterranean diet (MedD) and its effects on MetS is accurate?
a. The MedD is less effective than vegetarian or vegan diets in reducing inflammatory markers associated with MetS.
b. Consumption of red and processed meat is a component of the MedD and positively influences cardiovascular risk markers.
c. Higher adherence to the MedD is associated with lower n-3 levels in tissues, contrary to its positive effects on MetS.
d. The MedD is linked to improvements in various cardiovascular risk markers and has the potential to benefit individuals with MetS.
10. What is not a limitation of many studies examining the role of omega-3 fatty acids in the management of MetS?
a. The lack of high-quality n-3 supplements in the market
b. Variability in n-3 dosing and standardization in studies
c. Inconsistent findings on the effects of n-3 on inflammatory markers
d. The use of rodent models in research studies
References
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2. Shearer GC, Borkowski K, Puumala SL, Harris WS, Pedersen TL, Newman JW. Abnormal lipoprotein oxylipins in metabolic syndrome and partial correction by omega-3 fatty acids. Prostaglandins Leukot Essent Fatty Acids. 2018;128:1-10.
3. Jang H, Park K. Omega-3 and omega-6 polyunsaturated fatty acids and metabolic syndrome: a systematic review and meta-analysis. Clin Nutr. 2020;39(3):765-773.
4. Ding D, Li Y, Xiao M, et al. Erythrocyte membrane polyunsaturated fatty acids are associated with incidence of metabolic syndrome in middle-aged and elderly people—an 8.8-year prospective study. J Nutr. 2020;150(6):1488-1498.
5. Albracht-Schulte K, Kalupahana NS, Ramalingam L, et al. Omega-3 fatty acids in obesity and metabolic syndrome: a mechanistic update. J Nutr Biochem. 2018;58:1-16.
6. Palmer MK, Toth PP. Trends in lipids, obesity, metabolic syndrome, and diabetes mellitus in the United States: an NHANES analysis (2003–2004 to 2013–2014). Obesity. 2019;27(2):309-314.
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8. Troesch B, Eggersdorfer M, Laviano A, et al. Expert opinion on benefits of long-chain omega-3 fatty acids (DHA and EPA) in aging and clinical nutrition. Nutrients. 2020;12(9):2555.
9. Coltell O, Sorlí JV, Asensio EM, et al. Genome-wide association study for serum omega-3 and omega-6 polyunsaturated fatty acids: exploratory analysis of the sex-specific effects and dietary modulation in Mediterranean subjects with metabolic syndrome. Nutrients. 2020;12(2):310.
10. Hirode G, Wong RJ. Trends in the prevalence of metabolic syndrome in the United States, 2011–2016. JAMA. 2020;323(24):2526-2528.
11. Sheppard KW, Cheatham CL. Omega-6/omega-3 fatty acid intake of children and older adults in the US: dietary intake in comparison to current dietary recommendations and the Healthy Eating Index. Lipids Health Dis. 2018;17(1):43.
12. O’Mahoney LL, Matu J, Price OJ, et al. Omega-3 polyunsaturated fatty acids favourably modulate cardiometabolic biomarkers in type 2 diabetes: a meta-analysis and meta-regression of randomized controlled trials. Cardiovasc Diabetol. 2018;17(1):98.
13. Jakobsen MU, Madsen L, Skjoth F, et al. Dietary intake and adipose tissue content of long-chain n-3 PUFAs and subsequent 5-y change in body weight and waist circumference. Am J Clin Nutr. 2017;105(5):1148-1157.
14. Chaves LO, Carraro JCC, Vidigal FC, Bressan J. Higher waist circumference is related to lower plasma polyunsaturated fatty acids in healthy participants: metabolic implications. J Am Coll Nutr. 2019;38(4):342-350.
15. Yokoyama M, Origasa H, Matsuzaki M, et al. Effects of eicosapentaenoic acid on major coronary events in hypercholesterolaemic patients (JELIS): a randomised open-label, blinded endpoint analysis. Lancet. 2007;369(9567):1090-1098.
16. Tureck C, Barboza BP, Bricarello LP, et al. Scientific evidence of the association between oral intake of OMEGA-3 and OMEGA-6 fatty acids and the metabolic syndrome in adolescents: a systematic review. Nut Metab Cardiovasc Dis. 2022;32(12):2689-2704.
17. Charles-Messance H, Mitchelson KAJ, De Marco Castro E, Sheedy FJ, Roche HM. Regulating metabolic inflammation by nutritional modulation. J Allergy Clin Immunol. 2020;146(4):706-720.
18. Harrison S, Couture P, Lamarche B. Diet quality, saturated fat and metabolic syndrome. Nutrients. 2020;12(11):3232.
19. Millar SR, Navarro P, Harrington JM, Perry IJ, Phillips CM. Dietary quality determined by the healthy eating index-2015 and biomarkers of chronic low-grade inflammation: a cross-sectional analysis in middle-to-older aged adults. Nutrients. 2021;13(1):222.
20. Fallaize R, Livingstone KM, Celis-Morales C, et al. Association between diet-quality scores, adiposity, total cholesterol and markers of nutritional status in European adults: findings from the Food4Me study. Nutrients. 2018;10(1):49.
21. Castro-Barquero S, Ruiz-León AM, Sierra-Pérez M, Estruch R, Casas R. Dietary strategies for metabolic syndrome: a comprehensive review. Nutrients. 2020;12(10):2983.
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