INTRODUCTION

Omega-3 fatty acids are polyunsaturated fatty acids (PUFAs) commonly found in marine fish oil as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and their function in obesity, diabetes, hypertriglyceridemia, mental state, and cognitive function has been studied in many observational and randomized prospective controlled clinical studies (¹-⁴). Dietary fish oil supplementation reduces body fat mass by increasing lipid oxygenation, and decreases mortality related to stroke and diabetes, which is related to long-chain omega-3 PUFA intake (⁵,⁶). There is controversy on the effect of addition of omega-3 PUFAs to weight loss diets for the treatment of obesity. It has been demonstrated that long-chain PUFA supplementation reduces energy intake in obese women (⁷). PUFA supplementation might be beneficial in reducing obesity by decreasing appetite, increasing fat oxidation, and reducing fat deposition (⁸). A high omega-6/omega-3 ratio in the diet is associated with insulin resistance and weight gain in both animal and human studies; on the contrary, high omega-3 intake leads to weight loss and decreases the risk for obesity (⁹). Some studies demonstrate positive effects of omega-3 PUFA supplementation on weight loss and body fat mass reduction. Keshavarz et al. have found a decrease in body weight with omega-3 supplementation in obese dieting women (¹⁰). It is also a fact that omega-3 long-chain PUFA supplementation besides increasing weight loss decreased insulin, insulin resistance (HOMA-IR), TNF-α and leptin, and increased adiponectin in obese pre-pubertal and pubertal children (¹¹). In another study supplementation with EPA 1600 mg and DHA 800 mg decreased fat mass in healthy adults (¹²). On the other hand, some studies do not find a decrease in weight with omega-3 supplementation (⁷,¹³). In animal studies, omega-3 PUFAs are found to have a role in reducing retroperitoneal and epididimal fat mass (¹⁴). However, human research suggests that omega-3 PUFAs may not have beneficial effects on weight loss, but they may decrease appetite and prevent gaining more weight or help maintaining weight after a weight loss diet (¹⁵,¹⁶). The mechanisms of omega-3 PUFA effects on weight loss and body fat mass reduction may be related to: a modulation of lipid metabolism; regulation of adipokines such as adiponectine and leptin, and a decrease in inflammation in the adipose tissue; suppression of appetite; changes in carbohydrate metabolism; increases in energy consumption due to thermogenesis, and stimulating mechanisms in muscle anabolism (¹⁵).

Docosahexaenoic acid (DHA) is a component of neuronal membranes and DHA is required for brain functions such as neurotransmission or synaptic plasticity (¹⁷). It has been demonstrated that DHA supplementation has protective effects against the development of Alzheimer's disease by decreasing amyloid-β production, accumulation and toxicity in rats (¹⁸). DHA derivatives are also found to have neuroprotective properties by preventing neuronal apoptosis (¹⁹) and decreasing oxidative stress (²⁰). Even though the beneficial effects of omega-3 PUFAs have been demonstrated in animal studies, there is heterogeneity and inconsistency in the literature on the benefits of omega-3 supplementation for weight loss, body fat mass reduction, and cognitive functioning in human studies.

A recent review suggests that omega-3 PUFA supplementation may have a positive effect on cognitive function (²¹). The effect of omega-3 supplementation on cognitive improvement or cognitive decline prevention in cognitively healthy adults is not clear since there are not many controlled clinical trials to evaluate the potential benefit of omega-3 supplementation in these individuals; however, based on evidence from animal studies, there is promise for this population to benefit from omega-3 PUFA supplementation (²²).

Cognitive functions are affected by factors such as age, genetic background and nutrition (²³). There is also evidence of an association of weight loss with cognitive function in obese individuals. Weight loss may improve cognitive performance in obese and overweight individuals given that significantly improved attention and executive function were observed with weight loss in obese subjects (²⁴). There are numerous studies on the effect of omega-3 PUFAs and their role on cognitive functions, especially on the prevention of cognitive decline and dementia (²⁵). Epidemiologic studies support the protective effects of omega-3 PUFAs on cognitive functions. There are also some studies suggesting that omega-3 PUFAs have no effect on cognitive functions (²⁶,²⁷).

In this study, we aimed to investigate the possible effects of omega-3 PUFA supplementation on weight loss, body composition, and cognitive function in overweight or obese individuals on a weight loss diet.

MATERIAL AND METHODS

We hypothesized that regular daily use of omega-3 PUFA supplementation ameliorates cognitive functions and weight loss in overweight or obese individuals on a weight loss diet. After the institutional ethics committee's approval, 40 volunteering overweight or obese adult individuals with body mass index (BMI) between 27.0 and 35.0 kg/m², aged 30-60 years, and consulting at a private nutrition and diet clinic were included in the study. Sample size was determined to detect 5-point changes in the Montreal Cognitive Assessment (MoCA) test scores with a power of 90 % and an alpha error of 0.05. Individuals with a chronic systemic disease other than obesity and hyperlipidemia, such as hypertension, coronary artery disease, malignancies, endocrine and metabolic diseases such as diabetes, hyperthyroidism etc., were excluded from the study. Other exclusion criteria were regular physical activity, performing professional sports, and previous regular use of supplements, vitamins and minerals. Individuals who were noncompliant with the study, such as those who did not follow the study diet, did not use the omega-3 capsules, or did not show up for follow-up visits were also excluded.

Written informed consents were obtained from all subjects. Subjects were randomly allocated into a control or an omega-3 group. Demographic parameters, nutrition habits and physical activity status were evaluated using a questionnaire. Subjects were also asked to record their detailed food consumption and physical activities using a form, for three consecutive days, one weekend and two week days, before the onset of the diet and at the end of 12 weeks in order to monitor compliance with their diet (²⁸). The medical doctor in the research team evaluated and approved the suitability of the subjects to be participants in the study. The subjects in the control group (n = 20) were involved in a weight loss diet program. The subjects in the omega-3 group (n = 20) received supplementation with 1020 mg of omega-3 PUFAs per day (EPA 580 mg, DHA 390 mg, 50 mg of other omega-3 PUFAs) in addition to their weight loss diet program. The weight loss diet was organized individually for each subject according to their lifestyle and nutrition habits. Daily energy intake was planned using basal metabolic rate and physical activity (²⁹,³⁰).

The diet was designed to provide 55-60 % of daily energy from complex carbohydrates, 25-30 % from fats, and 12-15 % from proteins. Weekly fish consumption was set to be similar in all of the subjects. Salmon 150 g was provided twice a week in the diet of all subjects. Anthropometric measurements, including height, waist perimeter, total body weight, total body fat mass, body fat distribution, body muscle mass, and body mass index (BMI) were obtained at onset and at weeks 4, 8 and 12. A Tanita MC 180 Multi-Frequency Body Composition Analyzer Scale (Tanita Corporation, Tokyo, 174- 8630, Japan) was used for analyzing body composition and calculating basal metabolic rate according to weight. A tape measure and a stadiometer were used for measuring height and waist circumference (³¹).

A psychologist, blinded to the study groups, evaluated the cognitive functions of the subjects using the Montreal Cognitive Assessment (MoCA) test at diet onset as a pretest and at the end of the 12^th week (³²-³⁶).

The normal distributions of the subjects were evaluated using the Kolmogorov-Smirnov test. Independent-sample T-tests were used for comparing differences between groups in parameters demonstrating a normal distribution. The non-parametric Mann-Whitney U-test was used to compare the differences between groups for those parameters with no normal distribution. For comparing the effects of the intervention and time within groups, a repeated measures T-test was used for parameters with normal distribution. For parameters that did not demonstrate a normal distribution the non-parametric Wilcoxon's signed rank test was used instead; p-values less than 0.05 were considered statistically significant. Data are presented as mean and standard deviation. All statistical analyses were carried out using the IBM SPSS software (version 21.0, IBM International Business Machines Inc. Armonk, NY, USA).

RESULTS

All subjects followed their diet and took omega-3 supplements without reporting any intolerance or incompliance. They reported no change in their physical activities and lifestyle. Daily energy intake, macronutrients and micronutrients in diet food consumption records, provided by the subjects, at onset, at the end of week 6, and at the end of the study demonstrated no statistically significant differences between study groups (p > 0.05).

Subject age, gender, weight, height, BMI, waist measurements and physical activity factors at study onset in each group are listed in table I. There were no statistically significant differences between groups (p > 0.05).

Table I. Demographic and anthropometric data at onset. 

Mean ± SD. p > 0.05.

Body composition data at study onset regarding fat mass, fat percentage, abdominal fat mass, abdominal fat percentage, muscle mass, muscle percentage, and total body water of the subjects at study onset in each group are listed in table II. There were no statistically significant differences between groups (p > 0.05).

Table II. Body composition data at onset. 

Mean ± SD. p > 0.05 between groups.

When weight, BMI and waist measurements were analyzed, significant decreases over time were observed in both the control and omega-3 groups; however, there were no statistically significant differences observed between the groups (Table III).

Table III. Weight, BMI and waist measurements. 

Mean ± SD. p > 0.05 between groups.

Significant decreases over time were observed in both the control and omega-3 groups in subject weight, total fat mass, and abdominal fat mass. The decreases in total fat weight and total fat percentage were similar in both groups. The decrease in abdominal fat mass was greater in the omega-3 group than in the control group (p = 0.05).

Abdominal fat percentage decreased significantly more in the omega-3 group compared to the control group (p = 0.043) (Table IV).

Table IV. Total and abdominal fat. 

Mean ± SD.

^*p < 0.05 within time;.

^†p ≤ 0.05 between groups.

When MoCA scores at study onset and at week 12 were compared, MoCA scores were found to be increased in both the control and omega-3 groups. Increases were not statistically different between the omega-3 and the control groups (p > 0.05) (Table V).

Table V. MoCA scores. 

p > 0.05 between groups.

DISCUSSION

Omega-3 PUFAs are promising supplements in the prevention and treatment of various cardiovascular, inflammatory, immunological, psychological, and neurological disorders, that have a wide range of safe doses, and have been approved by the European Food Safety Authority (EFSA) (³⁷). Research data point to beneficial effects of omega-3 PUFAs in metabolic syndrome, cardiovascular diseases and other degenerative diseases related to aging (³⁸-⁴⁰). There are numerous studies indicating a negative association between increased BMI or body weight index and omega-3 index (plasma n-3 PUFA or O3I-omega-3 index) (⁴¹-⁴⁴).

Scientific evidence about the effect of omega-3 PUFAs on weight loss is inconsistent. In a study by Ruzickova et al. (⁴⁵), supplementation with EPA/DHA of marine origin is found to be effective in limiting the development of obesity by decreasing accumulation of body fat through limiting both fat cell hypertrophy and hyperplasia in mice. Minami et al. (⁴⁶) have noted a decrease in abdominal fat with EPA supplementation in diabetic rats. Soni et al. (⁴⁷) have reported a reduction in lipid accumulation in adipose tissues of mice on a high fat diet with EPA and DHA supplementation, as well as anti-inflammatory effects. Human studies have some conflicting outcomes. DeFina et al. (⁴⁸) studied the effects of omega-3 PUFAs on body weight loss in 81 obese or overweight subjects for a period of 6 months. No significant difference was observed in body weight between the omega-3 and placebo groups. Some studies suggest that omega-3 PUFA supplementation may not help in reducing body weight but may be helpful in maintaining weight loss and preventing further increases in weight (¹⁵).

In a study of healthy adult volunteers on a three-week control diet, Couet et al. (⁵) reported that dietary fish oil substitution decreased body fat mass, increased basal lipid oxidation, and decreased the basal respiratory quotient.

In our study we observed significant decreases in BMI and abdominal waist measurements over time; however, we could not find any significant differences between the omega-3 and control groups. Munro and Garg (⁴⁹,⁵⁰) reported that omega-3 PUFAs are not effective in assisting weight loss, which is in concordance with our findings; however, they observed a significant decrease in fat mass in obese patients. In a different setting, Munro and Garg (⁵¹) have also noted that a time-dependent effect may be present in helping weight loss with the prior administration of long-chain omega-3 PUFAs. They noted that omega-3 PUFA supplementation prior to a very low-energy diet was effective in females compared to males. They suggested that females may be more responsive to metabolism of PUFA, possibly because of the estrogen hormone. They also noted that their sample size was small and a longer period of intervention might be necessary.

Even though we found no significant differences in body fat mass, we observed a significant reduction in abdominal fat mass and abdominal fat percentage in the omega-3 group as compared to the control group. This is consistent with several other studies. Matsumura K. evaluated the effect of eicosapentaenoic acid (EPA) supplementation, 1800 mg/day, on visceral fat in 165 subjects using abdominal computed tomography (⁵²). No difference in visceral fat was observed in female subjects; however, a significant decrease in visceral fat was found in male subjects receiving EPA 1800 mg/day after 6 months. We also observed a decrease in abdominal fat over time in our study. Our daily EPA dose was lower, and the duration of the study was shorter than that of the study by Matsumura. Even though the male/female ratios in our study groups were not statistically different, our study was not set to compare gender differences, which may have an impact on the study.

Kabir M et al. (⁵³) have reported a reduction in adiposity after treatment with omega-3 PUFAs. The study was carried out on 27 women with type-2 diabetes and without hypertriglyceridemia. The treatment group received fish oil containing 1800 mg of EPA and DHA, which was higher than in our study, for two months. Total fat mass, adipocyte diameter and atherogenic markers decreased without a decline in insulin sensitivity. Expression of some inflammation-related genes in the adipose tissue, measured by real-time PCR, also decreased indicating local blunting of inflammation in the adipose tissue.

Itariu et al. (⁵⁴) used 900 mg/day of EPA and DHA supplementation for eight weeks in 55 non-diabetic obese (BMI > 40 kg/m²) patients scheduled for bariatric surgery. They found that omega-3 supplementation decreased expression of numerous inflammatory genes analyzed in visceral and subcutaneous adipose tissue compared to the control group (p < 0.05). The study revealed that treatment with omega-3 PUFAs enhanced the production of anti-inflammatory eicosanoids, thus it modulated systemic inflammation positively, and improved lipid metabolism in visceral and subcutaneous adipose tissue.

There are other studies that point to the anti-inflammatory effects of omega-3 PUFAs in the adipose tissue (⁵⁵,⁵⁶). The noted anti-inflammatory effects promise benefits in the long-term management of obesity.

In a study carried out on 58 overweight children with nonalcoholic fatty liver disease, docosahexaenoic acid supplementation was also found to be effective in decreasing liver and visceral fat, serum triglycerides, and fasting insulin (⁵⁷).

Thorsdottir et al. (¹⁶) studied the effect of fish and fish oil in a randomized controlled trial of nutritionally balanced, energy-restricted 8-week diet on 324 young overweight adults aged 20-40 years. The study demonstrated an increase in weight loss in male subjects on fish oil and fish containing diets compared to the control group. The waist circumference decreased in the fish oil group. We also found a decrease in waist circumference in our study over time; however, we did not observe any significant differences between the study groups. Thorsdottir et al. (¹⁶) gave 450 grams of cod or salmon per week, or 3 grams of fish oil per day, which is a higher dose than our intervention's. The study had a larger sample size compared to our study, and demonstrated significance in male subjects only.

In a prospective 6-week study on 44 adults by Noreen et al. (¹²), supplementation with 1,600 mg/day of EPA and 800 mg/day of DHA demonstrated a significant reduction in body fat mass. Abdominal fat mass was not analyzed. They used a higher dosage of omega-3 and the intervention was shorter than in our study. Even though we observed a decrease in fat mass at the 8^th week of our study, we could not find any statistically significant difference between groups in repeated measures. Even so, we may suggest that the findings of Noreen et al. (¹²) do not contradict our results. Human studies with omega-3 supplementation have revealed conflicting results. We have found a difference in abdominal fat mass and percentage with omega-3 PUFA supplementation; however, we did not find any significant effect in weight loss. Some factors affecting the results may include etiology of obesity, age, BMI of subjects, dose of supplement, EPA/DHA ratio in supplement, study duration, and a possible gender effect on weight loss. Another factor may be the temporal effect of the supplementation. Supplementation prior to a weight loss diet may be more effective or the effect of the supplement may be temporary as noted in other studies (⁵¹). Further studies using higher doses and greater sample sizes are required to reveal the temporal effects of omega-3 PUFA supplementation on fat mass reduction.

Several animal and human studies point to an impact of calorie restriction on cognitive functions, with benefits that integrate structural, physiological, and biochemical alternations (⁵⁸). The possible mechanisms of calorie restriction and weight loss on cognition are reduction in oxidative stress, activation of anti-inflammatory responses, increased cell resistance to stress, and neurogenesis, endorsing synaptic plasticity (⁵⁹). Inflammation, particularly low-degree chronic inflammation, has effects on early brain development, neurodegenerative disorders, and some brain functions (⁶⁰,⁶¹). It has been established that inflammation has an impact on cognitive function and mood disorders (⁶²). Nutrition and nutrients have many pro- and anti-inflammatory effects that may have potential outcomes involving cognitive functions (⁶³-⁶⁵). The neuroinflammatory and neurodegenerative mechanisms in overweight and obese individuals lead to structural changes in the brain and cerebellum, which may play a role in the impairment of cognitive functions (⁶⁶). It is established that omega-3 PUFA supplementation has beneficial effects on functional capacity and cognitive functions, especially in the elderly (⁶⁷-⁶⁹).

The effect of omega-3 supplementation on cognitive functions in children and young or older adults is still controversial (⁷⁰,⁷¹).

When we compared the 12^th-week MOCA scores with the pre-intervention scores a slight increase was noted in both the control and omega-3 groups; however, the increase was statistically insignificant. Moreover, the scores did not demonstrate any differences between the study and control groups with statistical significance (Table V).

Pase et al. (⁷²) studied the effect of fish oil and multivitamins on cognitive and cardiovascular functions in 160 healthy adults. The subjects were allocated to four groups to receive 3 grams of fish oil (240 mg of EPA and 240 mg of DHA) and multivitamins, 6 grams of fish oil (480 mg of EPA and 480 mg of DHA) and multivitamins, only 6 grams of fish oil (480 mg of EPA and 480 mg of DHA) or placebo. The Swinburne University Computerized Cognitive Assessment Battery was used for evaluating cognitive functions. The study could not demonstrate a significant change in cognitive function, which is consistent with our study.

Another study by Dangour et al. (⁷³) on 867 elderly adults aged 70-79 without previous cognitive impairment found no difference in cognitive function after utilizing EPA 200 mg EPA and DHA 500 mg for two years compared to olive oil as placebo. Several other randomized controlled studies on the effect of omega-3 PUFA supplementation could not reveal a beneficial effect on memory, reactivity, attention, reasoning, mood or mini mental state examination. The dose of omega-3 PUFA supplementation, the relatively small sample sizes, and the probable short duration of the studies compared to time to onset of effect may be some reasons for the restraint (⁷⁴-⁷⁷).

Howe et al. (⁷⁸) found an increase in cerebrovascular responsiveness (CVR) to hypercapnia in mildly hypertensive older women taking 1600 mg of DHA and 400 mg of EPA supplement per day for 20 weeks. This effect was not present in male subjects.

A recent study by Patan et al. (⁷⁹) compared the effects of EPA- or DHA-rich omega-3 PUFA supplementation on cognitive function, memory and prefrontal cortex hemoglobin oxygenation. The study was carried out on 310 healthy young adults aged 25-49. The subjects did not smoke or use any legal medications or illicit drugs, and did not have any major illnesses. The BMI of the subjects was between 18.5 and 35 kg/m², and blood pressures were lower than 159/99 mm Hg. The subjects received placebo or DHA-rich oil (900 mg of DHA/day and 270 mg of EPA/day) or EPA-rich oil (360 mg of DHA/day and 900 mg of EPA/day) for 26 weeks. Global cognitive function with regard to accuracy and speed improved in the EPA-rich group. The accuracy of memory was also better in the EPA-rich group. Prefrontal cortex hemoglobin oxygenation was reduced in both omega-3 groups when compared to the placebo group. These findings impress that the EPA/DHA ratio may have an impact on cognitive functions. Even though we used EPA-rich omega-3 PUFAs in our study, the EPA/DHA ratio was not as high as that referred to in the study.

The effect of weight loss on cognitive function is another subject of interest. Zeighami et al. (⁸⁰) studied the effect of weight loss on spontaneous neural activity in 57 severely obese patients who lost weight after bariatric surgery. Functional MRI was used to find out neural activity changes as indexed by fractional amplitude of low frequency fluctuations (fALFF). The study revealed widespread global and regional increases in resting neural activity with weight loss, and probable metabolic improvements associated with it.

A meta-analysis by Mazereeuw et al. (⁸¹), did not identify a beneficial effect of omega-3 PUFA supplementation on Alzheimer's disease patients or healthy subjects; however, a limited improvement on the subjects with previous cognitive impairment was revealed. A cross-sectional study on 299 healthy young women aged 18-35 years revealed reduced cognitive performance in attention with a computerized cognition testing platform in women with low omega-3 PUFA status (⁸²). Another study on 391 non-demented elderly individuals did not identify any association between plasma omega-3 PUFA concentrations and cognitive function (⁸³). In a study by Johnson et al. (⁸⁴), 4-month supplementation with DHA (800 mg /day) and/or luthein (12 mg /day) had beneficial effects on verbal fluency, memory, and rate of learning in women aged 60-80 years.

The effect of DHA supplementation on age related cognitive deterioration is underlined in several studies. Yurko-Mauro et al. (⁸⁵) have studied the effect of 900 mg/day of DHA supplementation for 24 weeks in 485 adults with age-related cognitive decline, aged over 55 years. They found that DHA supplementation improved immediate and delayed verbal and episodic memory, and learning functions in healthy adults with age-related cognitive decline. In another study on elderly adults aged 62 -80, fish oil supplementation (EPA + DHA: 2.4 g/day) improved working memory performance, and enhanced neuronal response to working memory in the posterior cingulate cortex, demonstrated by functional magnetic resonance imaging (fMRI) (⁸⁶). Another study on elderly adults aged over 60 years, with mild cognitive impairment, demonstrated that 480 mg of DHA and 720 mg of EPA supplementation for 6 months were beneficial in improving cognitive functions with differences regarding gender (⁸⁷). The effect of subject age and gender, the presence of cognitive decline, and the dose and duration of supplementation might be possible reasons for the differences in outcomes compared with our study.

In a study on 176 healthy young adults, Stonehouse et al. (⁸⁸) found that high-dose DHA 1160 mg/day for 6 months improved working memory in men and episodic memory in women. A recent review article has suggested that gender is a factor that influences human omega-3 PUFA concentrations (⁸⁹), thus considering gender as an independent variable may be valuable for upcoming trials on the effects of omega-3 supplementation.

In a randomized controlled study focusing on older adults aged over 70 with a low omega-3 index and subjective memory complaints, but without clinical dementia, executive functioning, as measured with the Controlled Oral Word Association Test (COWAT), declined less in subjects using omega-3 PUFA supplementation with a daily dose of DHA (800 mg) and EPA (a maximum amount of 225 mg) for 3 years (⁹⁰). However, several other cognitive tests did not reveal a similar effect (⁸²,⁸³).

A study of healthy adults aged 50 to 75, with 2200 mg/day of omega-3 PUFA supplementation for 26 weeks, improved object location memory (⁹¹). A study on loneliness-related episodic memory problems in 138 healthy, overweight, and sedentary adults aged 40-85 years revealed that both 1250 mg/day and 2500 mg/day of omega-3 supplementation attenuated the decline of episodic memory in lonely people (⁹²).

We used 1020 mg of omega-3 PUFA per day (580 mg of EPA, 390 mg of DHA, 50 mg of other omega-3 PUFAs) in our study. Even though we observed improvement in MOCA scores, we did not observe a statistically significant difference between the omega-3 and control groups. Dosage of supplement, duration of intervention, composition and EPA/DHA ratio of omega-3 supplements, gender and age of subjects, and category of cognitive tests vary in different studies, making it hard to clarify the effect of omega-3 PUFA supplementation on cognitive functions. To the best of our knowledge, there is no published study comparing the effect of omega-3 PUFA supplementation on MOCA scores in overweight or obese individuals on a weight loss diet. There are numerous studies indicating a positive effect of omega 3 PUFA supplementation on cognitive function (²¹). The baseline cognitive status of the subjects may also have an impact on cognitive function tests. The limitations of our study are a low number of male and elderly subjects, and the duration of the study. Previous minor memory or verbal cognitive impairment might also influence the outcomes of studies on cognitive functions. The diet of participants before the study, and compliance to the weight loss diet was evaluated using consumption records provided by the subjects, which may be inaccurate due to probable biases. The subjects in our study were middle-aged adults, and they did not have any previous cognitive impairment. A number of studies point to age-dependent beneficial effects of omega-3 PUFAs on cognition. Some studies suggest that older participants benefit more from omega-3 supplementation, although other studies recommend early omega-3 PUFA supplementation for the prevention of cognitive decline as more effective than an intervention in older individuals that already have cognitive decline (²²,⁹³). Focusing on a specific age group or gender might be helpful in finding out the effects of PUFAs on cognitive functions. Our study was not set to identify age or gender effects of omega-3 PUFA supplementation on MOCA scores. Another factor might be loneliness or social interaction with other individuals. Further studies with larger number of subjects, higher doses, or longer durations of supplementation and different tools to measure cognitive functions are required.

CONCLUSION

This study found an augmentation in the reduction of abdominal fat mass and percentage over time with omega-3 PUFA supplementation in overweight or obese individuals on a weight loss diet. Cognitive function, as measured by the Montreal Cognitive Assessment (MoCA) test, improved over time as the subjects lost weight; however, we did not find any significant difference with omega-3 PUFA supplementation. The clinical significance of these findings warrants further investigation. Studies on larger groups focusing on the effects of possible contributing factors such as BMI, genetic factors, loneliness, age, and gender with higher doses or longer duration of supplementation are required to identify the relationship and mechanisms of action of omega-3 PUFA supplementation on cognitive performance and weight loss.