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The Cochrane Database of Systematic... Apr 2020Studies suggest that a diet rich in omega-3 essential fatty acids may have beneficial anti-inflammatory effects for chronic conditions such as cystic fibrosis. This is... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Studies suggest that a diet rich in omega-3 essential fatty acids may have beneficial anti-inflammatory effects for chronic conditions such as cystic fibrosis. This is an updated version of a previously published review.
OBJECTIVES
To determine whether there is evidence that omega-3 polyunsaturated fatty acid supplementation reduces morbidity and mortality and to identify any adverse events associated with supplementation.
SEARCH METHODS
We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. Date of last search: 01 April 2020. We also searched online study registries and contacted authors. Date of last search: 12 February 2020.
SELECTION CRITERIA
Randomised controlled trials in people with cystic fibrosis comparing omega-3 fatty acid supplements with placebo.
DATA COLLECTION AND ANALYSIS
Two authors independently selected studies for inclusion, extracted data and assessed the risk of bias of the studies. The quality of the evidence was assessed using GRADE.
MAIN RESULTS
The searches identified 23 studies; five studies with 106 participants (children and adults) were included; duration of studies and interventions differed. Two studies compared omega-3 fatty acids to olive oil for six weeks; one study compared omega-3 fatty acids and omega-6 fatty acids to control capsules (customised fatty acid blends) for three months; one study compared a liquid dietary supplement containing omega-3 fatty acids to one without for six months; and one study compared omega-3 fatty acids to a placebo for 12 months. Three studies had a low risk of bias for randomisation, but the risk was unclear in the remaining two studies; all studies had an unclear risk of bias for allocation concealment. Three of the studies adequately blinded participants; the risk of bias for selective reporting was high in one study and unclear for four studies. Two studies reported the number of respiratory exacerbations. At three months, one study (43 participants) reported no change in antibiotic usage. At 12 months the second study (15 participants) reported a reduction in the number of pulmonary exacerbations and cumulative antibiotic days in the supplement group compared to the previous year (no data for the control group); very low-quality evidence means we are unsure whether supplementation has any effect on this outcome. With regards to adverse events, one six-week study (12 participants) reported no difference in diarrhoea between omega-3 or placebo capsules; the very low-quality evidence means we are unsure if supplementation has any effect on this outcome. Additionally, one study reported an increase in steatorrhoea requiring participants to increase their daily dose of pancreatic enzymes, but three studies had already increased pancreatic enzyme dose at study begin so as to reduce the incidence of steatorrhoea. One study (43 participants) reported stomach pains at three months (treatment or control group not specified). One six-week study (19 participants) reported three asthma exacerbations leading to exclusion of participants since corticosteroid treatment could affect affect essential fatty acid metabolism. Four studies reported lung function. One six-week study (19 participants) reported an increase in forced expiratory volume in one second (FEV) (L) and forced vital capacity (FVC) (L), but the very low-quality evidence means we are unsure if supplementation has any effect on lung function. The remaining studies did not report any difference in lung function at three months (unit of measurement not specified) or at six months and one year (FEV % predicted and FVC % predicted). No deaths were reported in any of the five studies. Four studies reported clinical variables. One study reported an increase in Schwachman score and weight alongside a reduction in sputum volume with supplementation compared to placebo at three months (data not analysable). However, three studies reported no differences in either weight at six weeks, in body mass index (BMI) standard deviation (SD) score at six months (very low-quality evidence) or BMI Z score at 12 months. Three studies reported biochemical markers of fatty acid status. One study showed an increase from baseline in both EPA and DHA content of serum phospholipids in the omega-3 group compared to placebo at three months and also a significant decrease in n-6/n-3 ratio in the supplement group compared to placebo; since the quality of the evidence is very low we are not certain that these changes are due to supplementation. One six-month cross-over study showed a higher EPA content of the neutrophil membrane in the supplement group compared to the placebo group, but, no difference in DHA membrane concentration. Furthermore, the leukotriene B to leukotriene B ratio was lower at six months in the omega-3 group compared to placebo. A one-year study reported a greater increase in the essential fatty acid profile and a decrease in AA levels in the treatment arm compared to placebo.
AUTHORS' CONCLUSIONS
This review found that regular omega-3 supplements may provide some limited benefits for people with cystic fibrosis with relatively few adverse effects: however, the quality of the evidence across all outcomes was very low. The current evidence is insufficient to draw firm conclusions or recommend routine use of these supplements in people with cystic fibrosis. A large, long-term, multicentre, randomised controlled study is needed to determine any significant therapeutic effect and to assess the influence of disease severity, dosage and duration of treatment. Future researchers should note the need for additional pancreatic enzymes when providing omega-3 supplementation or olive oil placebo capsules. More research is required to determine the exact dose of pancreatic enzyme required.
Topics: Adult; Bias; Child; Cystic Fibrosis; Dietary Supplements; Disease Progression; Fatty Acids, Omega-3; Fatty Acids, Omega-6; Forced Expiratory Volume; Humans; Olive Oil; Randomized Controlled Trials as Topic; Vital Capacity
PubMed: 32275788
DOI: 10.1002/14651858.CD002201.pub6 -
The British Journal of Nutrition Jun 2019We conducted a systematic review of randomised controlled trials (RCT) of increased intake of arachidonic acid (ARA) on fatty acid status and health outcomes in humans....
We conducted a systematic review of randomised controlled trials (RCT) of increased intake of arachidonic acid (ARA) on fatty acid status and health outcomes in humans. We identified twenty-two articles from fourteen RCT. Most studies were conducted in adults. These used between 80 and 2000 mg ARA per d and were of 1-12 weeks duration. Supplementation with ARA doses as low as 80 mg/d increased the content of ARA in different blood fractions. Overall there seem to be few marked benefits for adults of increasing ARA intake from the typical usual intake of 100-200 mg/d to as much as 1000 mg/d; the few studies using higher doses (1500 or 2000 mg/d) also report little benefit. However, there may be an impact of ARA on cognitive and muscle function which could be particularly relevant in the ageing population. The studies reviewed here suggest no adverse effects in adults of increased ARA intake up to at least 1000-1500 mg/d on blood lipids, platelet aggregation and blood clotting, immune function, inflammation or urinary excretion of ARA metabolites. However, in many areas there are insufficient studies to make firm conclusions, and higher intakes of ARA are deserving of further study. Based on the RCT reviewed, there are not enough data to make any recommendations for specific health effects of ARA intake.
Topics: Adult; Aged; Arachidonic Acid; Dietary Supplements; Fatty Acids, Unsaturated; Female; Humans; Male; Middle Aged; Nutritional Status; Randomized Controlled Trials as Topic
PubMed: 31130146
DOI: 10.1017/S0007114519000692 -
The British Journal of Nutrition Apr 2019Numerous health benefits are attributed to the n-3 long-chain PUFA (n-3 LCPUFA); EPA and DHA. A systematic literature review was conducted to investigate factors, other...
Numerous health benefits are attributed to the n-3 long-chain PUFA (n-3 LCPUFA); EPA and DHA. A systematic literature review was conducted to investigate factors, other than diet, that are associated with the n-3 LCPUFA levels. The inclusion criteria were papers written in English, carried out in adult non-pregnant humans, n-3 LCPUFA measured in blood or tissue, data from cross-sectional studies, or baseline data from intervention studies. The search revealed 5076 unique articles of which seventy were included in the qualitative synthesis. Three main groups of factors potentially associated with n-3 LCPUFA levels were identified: (1) unmodifiable factors (sex, genetics, age), (2) modifiable factors (body size, physical activity, alcohol, smoking) and (3) bioavailability factors (chemically bound form of supplements, krill oil v. fish oil, and conversion of plant-derived α-linolenic acid (ALA) to n-3 LCPUFA). Results showed that factors positively associated with n-3 LCPUFA levels were age, female sex (women younger than 50 years), wine consumption and the TAG form. Factors negatively associated with n-3 LCPUFA levels were genetics, BMI (if erythrocyte EPA and DHA levels are <5·6 %) and smoking. The evidence for girth, physical activity and krill oil v. fish oil associated with n-3 LCPUFA levels is inconclusive. There is also evidence that higher ALA consumption leads to increased levels of EPA but not DHA. In conclusion, sex, age, BMI, alcohol consumption, smoking and the form of n-3 LCPUFA are all factors that need to be taken into account in n-3 LCPUFA research.
Topics: Adult; Age Factors; Alcohol Drinking; Body Mass Index; Fatty Acids, Omega-3; Female; Humans; Male; Sex Factors; Smoking
PubMed: 30688181
DOI: 10.1017/S0007114519000138 -
The British Journal of Nutrition Dec 2018Diet has been investigated in relation to its ability to promote cognitive function. However, evidence is currently limited and has rarely been systematically reviewed,...
Diet has been investigated in relation to its ability to promote cognitive function. However, evidence is currently limited and has rarely been systematically reviewed, particularly in a mild cognitive impairment (MCI) population. This review examined the effect of diet on cognitive outcomes in MCI patients. A total of five databases were searched to find randomised controlled trial (RCT) studies, with diet as the main focus, in MCI participants. The primary outcome was incident dementia and/or Alzheimer's disease (AD) and secondary outcomes included cognitive function across different domains using validated neuropsychological tests. Sixteen studies met the inclusion criteria. There was a high degree of heterogeneity relating to the nature of the dietary intervention and cognitive outcomes measured, thus making study comparisons difficult. Supplementation with vitamin E (one study, n 516), ginkgo biloba (one study, n 482) or Fortasyn Connect (one study, n 311) had no significant effect on progression from MCI to dementia and/or AD. For cognitive function, the findings showed some improvements in performance, particularly in memory, with the most consistent results shown by B vitamins, including folic acid (one study, n 266), folic acid alone (one study, n 180), DHA and EPA (two studies, n 36 and n 86), DHA (one study, n 240) and flavonol supplementation (one study, n 90). The findings indicate that dietary factors may have a potential benefit for cognitive function in MCI patients. Further well-designed trials are needed, with standardised and robust measures of cognition to investigate the influence of diet on cognitive status.
Topics: Alzheimer Disease; Attention; Biomarkers; Cognition; Cognitive Dysfunction; Dementia; Diet; Dietary Supplements; Disease Progression; Docosahexaenoic Acids; Eicosapentaenoic Acid; Executive Function; Folic Acid; Ginkgo biloba; Humans; Language; Neuropsychological Tests; Phospholipids; Randomized Controlled Trials as Topic; Vitamin E
PubMed: 30409231
DOI: 10.1017/S0007114518002945 -
Orphanet Journal of Rare Diseases Jun 2018Despite early and ongoing dietary management with a phe-restricted diet, suboptimal neuropsychological function has been observed in PKU. The restrictive nature of the... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Despite early and ongoing dietary management with a phe-restricted diet, suboptimal neuropsychological function has been observed in PKU. The restrictive nature of the PKU diet may expose patients to sub-optimal nutritional intake and deficiencies which may impact normal brain function. A systematic review of the published literature was carried out, where possible with meta-analysis, to compare the status of nutrients (Nutrients: DHA, EPA phospholipids, selenium, vitamins B, B, E, C, A, D, folic acid, choline, uridine, calcium, magnesium, zinc, iron, iodine and cholesterol) known to be important for brain development and functioning between individuals with PKU and healthy controls.
RESULTS
Of 1534 publications identified, 65 studies met the entry criteria. Significantly lower levels of DHA, EPA and cholesterol were found for PKU patients compared to healthy controls. No significant differences in zinc, vitamins B, E and D, calcium, iron and magnesium were found between PKU patients and controls. Because of considerable heterogeneity, the meta-analyses findings for folate and selenium were not reported. Due to an insufficient number of publications (< 4) no meta-analysis was undertaken for vitamins A, C and B, choline, uridine, iodine and phospholipids.
CONCLUSIONS
The current data show that PKU patients have lower availability of DHA, EPA and cholesterol. Compliance with the phe-restricted diet including the micronutrient fortified protein substitute (PS) is essential to ensure adequate micronutrient status. Given the complexity of the diet, patients' micronutrient and fatty acid status should be continuously monitored, with a particular focus on patients who are non-compliant or poorly compliant with their PS. Given their key role in brain function, assessment of the status of nutrients where limited data was found (e.g. choline, iodine) should be undertaken. Standardised reporting of studies in PKU would strengthen the output of meta-analysis and so better inform best practice for this rare condition.
Topics: Brain; Docosahexaenoic Acids; Fatty Acids; Humans; Micronutrients; Phenylketonurias; Phospholipids
PubMed: 29941009
DOI: 10.1186/s13023-018-0839-x -
The American Journal of Psychiatry Jul 2018Genes, infection, malnutrition, and other factors affecting fetal brain development are a major component of risk for a child's emotional development and later mental...
Genes, infection, malnutrition, and other factors affecting fetal brain development are a major component of risk for a child's emotional development and later mental illnesses, including schizophrenia, bipolar disorder, and autism. Prenatal interventions to ameliorate that risk have yet to be established for clinical use. A systematic review of prenatal nutrients and childhood emotional development and later mental illness was performed. Randomized trials of folic acid, phosphatidylcholine, and omega-3 fatty acid supplements assess effects of doses beyond those adequate to remedy deficiencies to promote normal fetal development despite genetic and environmental risks. Folic acid to prevent neural tube defects is an example. Vitamins A and D are currently recommended at maximum levels, but women's incomplete compliance permits observational studies of their effects. Folic acid and phosphatidylcholine supplements have shown evidence for improving childhood emotional development associated with later mental illnesses. Vitamins A and D decreased the risk for schizophrenia and autism in retrospective observations. Omega-3 fatty acid supplementation during early pregnancy increased the risk for schizophrenia and increased symptoms of attention deficit hyperactivity disorder, but in later pregnancy it decreased childhood wheezing and premature birth. Studies are complicated by the length of time between birth and the emergence of mental illnesses like schizophrenia, compared with anomalies like facial clefts identified at birth. As part of comprehensive maternal and fetal care, prenatal nutrient interventions should be further considered as uniquely effective first steps in decreasing risk for future psychiatric and other illnesses in newborn children. [AJP at 175: Remembering Our Past As We Envision Our Future July 1959: Longitudinal Observations of Biological Deviations in a Schizophrenic Infant Barbara Fish described the course of an infant born with fluctuating motor problems who developed schizophrenia. (Am J Psychiatry 1959; 116:25-31 )].
Topics: Dietary Supplements; Fatty Acids, Omega-3; Female; Folic Acid; Humans; Mental Disorders; Micronutrients; Phosphatidylcholines; Pregnancy; Prenatal Care; Primary Prevention
PubMed: 29558816
DOI: 10.1176/appi.ajp.2018.17070836 -
The Cochrane Database of Systematic... Jan 2016Studies suggest that a diet rich in omega-3 essential fatty acids may have beneficial anti-inflammatory effects for chronic conditions such as cystic fibrosis. This is... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Studies suggest that a diet rich in omega-3 essential fatty acids may have beneficial anti-inflammatory effects for chronic conditions such as cystic fibrosis. This is an updated version of a previously published review.
OBJECTIVES
To determine whether there is evidence that omega-3 polyunsaturated fatty acid supplementation reduces morbidity and mortality and to identify any adverse events associated with supplementation.
SEARCH METHODS
We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. Authors and persons interested in the subject of the review were contacted.Date of last search: 13 August 2013.
SELECTION CRITERIA
Randomised controlled trials in people with cystic fibrosis comparing omega-3 fatty acid supplements with placebo.
DATA COLLECTION AND ANALYSIS
Two authors independently selected studies for inclusion, extracted data and assessed the risk of bias of the studies.
MAIN RESULTS
The searches identified 15 studies; four studies with 91 participants (children and adults) were included; duration of studies ranged from six weeks to six months. Two studies were judged to be at low risk of bias based on adequate randomisation but this was unclear in the other two studies. Three of the studies adequately blinded patients, however, the risk of bias was unclear in all studies with regards to allocation concealment and selective reporting.Two studies compared omega-3 fatty acids to olive oil for six weeks. One study compared a liquid dietary supplement containing omega-3 fatty acids to one without for six months. One study compared omega-3 fatty acids and omega-6 fatty acids to a control (capsules with customised fatty acid blends) for three months. Only one short-term study (19 participants) comparing omega-3 to placebo reported a significant improvement in lung function and Shwachman score and a reduction in sputum volume in the omega-3 group. Another study (43 participants) demonstrated a significant increase in serum phospholipid essential fatty acid content and a significant drop in the n-6/n-3 fatty acid ratio following omega-3 fatty acid supplementation compared to control. The longer-term study (17 participants) demonstrated a significant increase in essential fatty acid content in neutrophil membranes and a significant decrease in the leukotriene B4 to leukotriene B5 ratio in participants taking omega-3 supplements compared to placebo.
AUTHORS' CONCLUSIONS
This review found that regular omega-3 supplements may provide some benefits for people with cystic fibrosis with relatively few adverse effects, although evidence is insufficient to draw firm conclusions or recommend routine use of these supplements in people with cystic fibrosis. This review has highlighted the lack of data for many outcomes meaningful to people with or making treatment decisions about cystic fibrosis. A large, long-term, multicentre, randomised controlled study is needed to determine any significant therapeutic effect and to assess the influence of disease severity, dosage and duration of treatment. Future researchers should note the need for additional pancreatic enzymes.
Topics: Adult; Child; Cystic Fibrosis; Dietary Supplements; Fatty Acids, Omega-3; Fatty Acids, Omega-6; Humans; Randomized Controlled Trials as Topic
PubMed: 26730723
DOI: 10.1002/14651858.CD002201.pub5 -
Nutrients May 2015The Mediterranean diet has been proven to be highly effective in the prevention of cardiovascular diseases. Paraoxonase 1 (PON1) has been implicated in the development... (Review)
Review
The Mediterranean diet has been proven to be highly effective in the prevention of cardiovascular diseases. Paraoxonase 1 (PON1) has been implicated in the development of those conditions, especially atherosclerosis. The present work describes a systematic review of current evidence supporting the influence of Mediterranean diet and its constituents on this enzyme. Despite the differential response of some genetic polymorphisms, the Mediterranean diet has been shown to exert a protective action on this enzyme. Extra virgin olive oil, the main source of fat, has been particularly effective in increasing PON1 activity, an action that could be due to low saturated fatty acid intake, oleic acid enrichment of phospholipids present in high-density lipoproteins that favor the activity, and increasing hepatic PON1 mRNA and protein expressions induced by minor components present in this oil. Other Mediterranean diet constituents, such as nuts, fruits and vegetables, have been effective in modulating the activity of the enzyme, pomegranate and its compounds being the best characterized items. Ongoing research on compounds isolated from all these natural products, mainly phenolic compounds and carotenoids, indicates that some of them are particularly effective, and this may enhance the use of nutraceuticals and functional foods capable of potentiating PON1 activity.
Topics: Animals; Aryldialkylphosphatase; Cardiovascular Diseases; Carotenoids; Diet, Mediterranean; Disease Models, Animal; Fruit; Humans; Nuts; Olive Oil; Phenols; Protein Conformation; Risk Factors; Vegetables
PubMed: 26024295
DOI: 10.3390/nu7064068 -
PloS One 2015Subjective memory complaints are common with aging. Docosahexaenoic acid (DHA; 22:6 n-3) is a long-chain polyunsaturated fatty acid (LCPUFA) and an integral part of... (Meta-Analysis)
Meta-Analysis Review
INTRODUCTION
Subjective memory complaints are common with aging. Docosahexaenoic acid (DHA; 22:6 n-3) is a long-chain polyunsaturated fatty acid (LCPUFA) and an integral part of neural membrane phospholipids that impacts brain structure and function. Past research demonstrates a positive association between DHA plasma status/dietary intake and cognitive function.
OBJECTIVES
The current meta-analysis was designed to determine the effect of DHA intake, alone or combined with eicosapentaenoic acid (EPA; 20:5 n-3), on specific memory domains: episodic, working, and semantic in healthy adults aged 18 years and older. A secondary objective was to systematically review/summarize the related observational epidemiologic literature.
METHODS
A systematic literature search of clinical trials and observational studies that examined the relationship between n-3 LCPUFA on memory outcomes in healthy adults was conducted in Ovid MEDLINE and EMBASE databases. Studies of subjects free of neurologic disease at baseline, with or without mild memory complaints (MMC), were included. Random effects meta-analyses were conducted to generate weighted group mean differences, standardized weighted group mean differences (Hedge's g), z-scores, and p-values for heterogeneity comparing DHA/EPA to a placebo. A priori sub-group analyses were conducted to evaluate the effect of age at enrollment, dose level, and memory type tested.
RESULTS
Episodic memory outcomes of adults with MMC were significantly (P<.004) improved with DHA/EPA supplementation. Regardless of cognitive status at baseline, > 1 g/day DHA/EPA improved episodic memory (P<.04). Semantic and working memory changes from baseline were significant with DHA but no between group differences were detected. Observational studies support a beneficial association between intake/blood levels of DHA/EPA and memory function in older adults.
CONCLUSION
DHA, alone or combined with EPA, contributes to improved memory function in older adults with mild memory complaints.
Topics: Adult; Clinical Trials as Topic; Docosahexaenoic Acids; Drug Interactions; Eicosapentaenoic Acid; Humans; Memory; Observational Studies as Topic
PubMed: 25786262
DOI: 10.1371/journal.pone.0120391