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Impact of Replacement of Individual Dietary SFAs on Circulating Lipids and Other Biomarkers of Cardiometabolic Health: A Systematic Review and Meta-Analysis of Randomized Controlled Trials in Humans.
Sellem, L, Flourakis, M, Jackson, KG, Joris, PJ, Lumley, J, Lohner, S, Mensink, RP, Soedamah-Muthu, SS, Lovegrove, JA
Advances in nutrition (Bethesda, Md.). 2022;13(4):1200-1225
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Plain language summary
Cardiovascular disease is one of the leading causes of mortality worldwide, and metabolic disorders such as diabetes, hyperlipidaemia, and hypertension contribute to this risk. Cardiometabolic disease (CMD) can be reduced by reducing saturated fatty acids (SFAs) and replacing them with unsaturated fatty acids (UFAs). Dietary SFA's are classified as a whole group in general dietary guidelines. However, blood lipid levels and other biomarkers of CMD may be affected differently by individual dietary SFAs. In this systematic review and meta-analysis, 44 randomised controlled trials were included that investigated the effects of replacing SFAs with individual dietary SFAs or UFAs on markers of CMD. CMD markers like Total cholesterol (TC), LDL cholesterol, and apoB concentrations were significantly reduced by replacing 1.5%TE of palmitic acid with oleic acid or UFAs for 14 days. The research also showed associations between apoB and LDL-cholesterol and apoA-I and HDL-cholesterol concentrations. Dietary palmitic acid substituted with UFAs significantly reduced fasting LDL-cholesterol and total cholesterol. The majority of studies included in this study focused on dietary palmitic acid and not much on stearic acid, myristic acid, or lauric acid. Therefore, further robust studies are required to assess the effect of individual dietary SFAs on the markers of CMD, including markers of inflammation, hemostasis, glycemic control, or metabolic hormones. Healthcare professionals can use this study to understand the benefits of substituting SFAs with UFAs on CMD markers.
Abstract
Little is known of the impact of individual SFAs and their isoenergetic substitution with other SFAs or unsaturated fatty acids (UFAs) on the prevention of cardiometabolic disease (CMD). This systematic literature review assessed the impact of such dietary substitutions on a range of fasting CMD risk markers, including lipid profile, markers of glycemic control and inflammation, and metabolic hormone concentrations. Eligible randomized controlled trials (RCTs) investigated the effect of isoenergetic replacements of individual dietary SFAs for ≥14 d on ≥1 CMD risk markers in humans. Searches of the PubMed, Embase, Scopus, and Cochrane CENTRAL databases on 14 February, 2021 identified 44 RCTs conducted in participants with a mean ± SD age of 39.9 ± 15.2 y. Studies' risk of bias was assessed using the Cochrane Risk of Bias tool 2.0 for RCTs. Random-effect meta-analyses assessed the effect of ≥3 similar dietary substitutions on the same CMD risk marker. Other dietary interventions were described in qualitative syntheses. We observed reductions in LDL-cholesterol concentrations after the replacement of palmitic acid (16:0) with UFAs (-0.36 mmol/L; 95% CI: -0.50, -0.21 mmol/L; I2 = 96.0%, n = 18 RCTs) or oleic acid (18:1n-9) (-0.16 mmol/L; 95% CI: -0.28, -0.03 mmol/L; I2 = 89.6%, n = 9 RCTs), with a similar impact on total cholesterol and apoB concentrations. No effects on other CMD risk markers, including HDL-cholesterol, triacylglycerol, glucose, insulin, or C-reactive protein concentrations, were evident. Similarly, we found no evidence of a benefit from replacing dietary stearic acid (18:0) with UFAs on CMD risk markers (n = 4 RCTs). In conclusion, the impact of replacing dietary palmitic acid with UFAs on lipid biomarkers is aligned with current public health recommendations. However, owing to the high heterogeneity and limited studies, relations between all individual SFAs and biomarkers of cardiometabolic health need further confirmation from RCTs. This systematic review was registered at www.crd.york.ac.uk/prospero/ as CRD42020084241.
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Low-glycaemic index diets in the management of blood lipids: a systematic review and meta-analysis.
Fleming, P, Godwin, M
Family practice. 2013;30(5):485-91
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Plain language summary
Dietary glycaemic index (GI) is a measure of the body’s response to digesting carbohydrates. Foods with a high GI score result in a rapid spike in blood glucose and insulin levels, and increased plasma-free fatty acids. These spikes may have a direct impact on cardiovascular health. The aim of this review was to examine the effectiveness of low-GI diets in the management of blood lipids. Proposed mechanisms of high-GI diets impacting cardiovascular health include increasing reactive oxygen species, potentiating endothelial dysfunction and promoting vascular inflammation. The meta-analysis showed that low-GI diets have a significant effect on lowering total cholesterol and low-density lipoprotein (LDL) cholesterol in 5-12 weeks. Based on this study, the authors’ conclusions suggest that a low-GI diet may positively impact the lipid profile, however, a large randomised controlled trial is needed on the effects of low-GI diets on blood lipids.
Abstract
BACKGROUND Dietary glycaemic index (GI) is a measure of the postprandial glycaemic response to carbohydrates. Observational studies have found increased triglycerides and decreased high-density lipoprotein levels in patients consuming higher GI foods. OBJECTIVE Our aim was to review and synthesize the evidence on the effect of low-glucose index diets on serum lipid levels. METHODS We conducted a systematic review and meta-analysis of randomized controlled trials on the effect of low-GI diets on serum lipid levels. We searched PubMed, Embase and Cochrane Library for published, English-language, randomized controlled trials comparing low-GI and high-GI diets for the management of blood lipids in the general population with at least 4 weeks of follow-up. We conducted a meta-analysis assuming a random effects model. RESULTS Four studies met the criteria for inclusion in the systematic review and meta-analysis. The individual studies did not always show a significant effect of a low-GI diet on serum lipids; however, when combined in a meta-analysis, low-GI diets were shown to have a significant effect on decreasing total cholesterol and low-density lipoprotein (LDL) cholesterol over a short time span (5-12 weeks). There was no significant effect on high-density lipoprotein or triglyceride levels. The forest plots for total cholesterol and LDL cholesterol did not show significant statistical heterogeneity (I (2) = 0%). CONCLUSION This meta-analysis suggests that a low-GI diet may help lower total and LDL cholesterol. The generalizability of these findings is likely limited by heterogeneity in individual study definitions of low- or high-GI diets.