Nutritional advice

Objectives:
Epidemiological studies have shown the preventive effects of olive oil consumption against cardiovascular events and all-cause deaths, but the results remain inconsistent. Therefore, this meta-analysis (review article) has been conducted.

Does higher olive oil consumption reduce the risk of cardiovascular disease and all-cause mortality?

Study design:
This review article included 13 prospective cohort studies.
These studies were published between 2003 and 2022, with follow-up intervals ranging from 4 to 28 years.
Most of studies collected the dietary data on olive oil intake based on food-frequency questionnaires and the outcome events were identified using International Classification of Diseases codes or other medical records.
All of the studies were assigned a NOS score of ≥7, indicating the evidence of high methodological quality.
There was no publication bias.

Results and conclusions:
The investigators found meta-analysis of 8 cohort studies (261,016 participants and 14,033 cardiovascular disease cases) showed versus lowest consumption of olive oil, high consumption of olive oil significantly reduced risk of cardiovascular disease with 15% [pooled RR = 0.85, 95% CI = 0.77 to 0.93, p 0.001, I2 = 41%, p = 0.107].
Subgroup analyses showed no significant differences between strata of study region, sample size, follow-up duration, sex and olive oil type.
The combined risk estimate of cardiovascular disease was not altered in the sensitivity analysis by omitting each study one at a time.

The investigators found meta-analysis of 11 cohort studies (713,000 participants and 173,817 deaths) showed versus lowest consumption of olive oil, high consumption of olive oil significantly reduced risk of all-cause mortality with 17% [pooled RR = 0.83, 95% CI = 0.77 to 0.90, p 0.001, I2 = 93%, p 0.001].
Excluding each report in sequence had no influence on the pooled result.
The combined RRs were similar between subsets stratified by the aforementioned features.

The investigators found in dose-response meta-analysis, a significantly reduced risk of 4% for cardiovascular disease per 5-g/day increase in olive oil intake [RR = 0.96, 95% CI = 0.93 to 0.99, p = 0.005].

The investigators found in dose-response meta-analysis, a significantly reduced risk of 4% for all-cause mortality per 5-g/day increase in olive oil intake [RR = 0.96, 95% CI = 0.95 to 0.96, p 0.001].

The investigators found non-linear associations of olive oil intake with cardiovascular disease and all-cause mortality [both p for non-linearity 0.001], with little additional or no risk reduction observed beyond the consumption of approximately 20 g/day.

The investigators concluded that olive oil consumption reduces the risk of cardiovascular disease and all-cause mortality. Such benefits seem to be obtained with an intake of olive oil up to 20 g/day. These results support the current dietary recommendations to increase the intake of olive oil instead of other fats for improving human health and longevity. Future prospective studies are required to further depict the dose-dependent cardiovascular and survival effects in relation to olive oil consumption.

Original title:
Olive oil consumption and risk of cardiovascular disease and all-cause mortality: A meta-analysis of prospective cohort studies by Xia M, Zhong Y, [...], Qian C.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9623257/

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Objectives:
Although numerous studies have reported the protective effect of nut consumption on cardiovascular risk, evidence for the role of peanuts in maintaining cardiometabolic health is inconclusive. Therefore, this meta-analysis (review article) has been conducted.

Does a high consumption of peanuts improve causally cardiovascular risk factors, such as cholesterol levels and LDL/HDL ratio?

Study design:
This review article included 10 RCTs (8 parallel RCTs and 3 crossover RCTs) with a total of 643 participants (316 males and 327 females) aged between 18 and 84 years from Asia, North America, Europa, South America and Australia.

The administered doses of peanuts ranged between 25 and 200 g/d, with follow-up periods of 2-24 weeks.

The strength of evidence varied from very low to moderate, depending on the outcomes.

Results and conclusions:
The investigators found meta-analysis of clinical trials revealed that peanut consumption was significantly associated with a decrease in triglycerides levels compared to the control interventions [MD = -0.13, 95% CI = -0.20 to -0.07, p 0.0001].
This significant reduction was most acute in healthy subjects [MD = -0.13, 95% CI = -0.25 to -0.00, p = 0.04] and in those who consumed peanuts or peanut butter [MD = -0.14, 95% CI = -0.20 to -0.07, p 0.0001].

The investigators found meta-analysis of clinical trials revealed that peanut consumption signicantly lowered total cholesterol levels among healthy consumers [MD = -0.40, 95% CI = -0.71 to -0.09, p = 0.01].

The investigators found meta-analysis of clinical trials revealed that peanut consumption signicantly lowered total cholesterol levels among healthy consumers [MD = -0.40, 95% CI = -0.71 to -0.09, p = 0.01].

The investigators found meta-analysis of clinical trials revealed that peanut consumption resulted in a signicantly lower LDL-cholesterol/HDL-cholesterol ratio among healthy consumers [MD = -0.19, 95% CI = -0.36 to -0.01, p = 0.03].

The investigators found, however, individuals at high cardiometabolic risk experienced a significant increase in body weight after the peanut interventions [MD = 0.97, 95% CI = 0.54 to 1.41, p 0.0001], although not in body fat or body mass index.

The investigators found, according to the dose-response analyses, body weight increased slightly with higher doses of peanuts.

The investigators concluded that consumption of 25-200 g/d peanuts during 2-24 weeks may causally reduce triglycerides and total cholesterol levels. May reduce because the strength of evidence varied from very low to moderate. To gain more knowledge about the effects of peanut products on cardiometabolic risk factors, more carefully designed studies in larger populations are needed.

Original title:
Effect of Peanut Consumption on Cardiovascular Risk Factors: A Randomized Clinical Trial and Meta-Analysis by Parilli-Moser I, Hurtado-Barroso S, […], Lamuela-Raventós RM.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9011914/

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Objectives:
Previous studies on the effect of Brassica vegetables on blood glucose and lipid profile have reported inconclusive findings. Therefore, this meta-analysis (review article) has been conducted.

Does higher Brassica vegetables consumption improve causally cardiovascular risk factors (levels of triglycerides, cholesterol, fasting blood sugar and glycated haemoglobin)?

Study design:
This review article included 9 RCTs with a total of 548 participants.

Results and conclusions:
The investigators found pooled analysis indicated a significant reduction in total cholesterol (TC) [SMD = -0.28, 95% CI = -0.48 to -0.08, p = 0.005] following Brassica vegetables consumption.

The investigators found, overall, Brassica vegetables had no significant impact on serum levels of triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, fasting blood sugar and glycated hemoglobin.

The investigators concluded that consumption of Brassica vegetables causally reduces total cholesterol concentration. However, further high-quality studies are needed to firmly establish the clinical efficacy of these plants.

Original title:
The effect of Brassica vegetables on blood glucose levels and lipid profiles in adults. A systematic review and meta-analysis by Darand M, Alizadeh S and Mansourian M.

Link:
https://pubmed.ncbi.nlm.nih.gov/35412701/

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Brassica vegetables are broccoli, Brussels sprouts, cabbage, cauliflower, collard greens, kale and turnips.

Objectives:
Although several meta-analyses have revealed the beneficial effects of dietary fiber intake on human health, some have reported inconsistent findings. Therefore, this umbrella meta-analysis (review article) has been conducted.

Does higher dietary fiber intake improve causally cardiovascular risk factors?

Study design:
This umbrella review article included 52 meta-analyses of RCTs with a total of 47,197 subjects.

Of the 52 meta-analyses, 35 used high-quality studies, 9 used studies with moderate quality, 7 did not report the quality of the included studies and 1 used low-quality studies.

The dosages and durations of dietary fiber intervention ranged from 3 g/day to 30 g/day (except for one study, which used guar gum at 15 mg/day and another study that used brown rice at 225 g/d) and 4 to 13 weeks, respectively.

Results and conclusions:
The investigators found, overall, higher dietary fiber intake significantly reduced:
-fasting plasma glucose [ES = -0.55, 95% CI = -0.73 to -0.38, p 0.001];
-fasting plasma insulin [ES = -1.22, 95% CI = -1.63 to -0.82, p 0.001];
-homeostasis model assessment of insulin resistance (HOMA-IR) [ES = -0.43, 95% CI = -0.60 to -0.27, p 0.001];

-glycosylated hemoglobin (HbA1c) [ES = -0.38, 95% CI = -0.50 to -0.26, p 0.001];
-serum level of total cholesterol [ES = -0.28, 95% CI = -0.39 to -0.16, p 0.001];
-low-density lipoprotein cholesterol (bad cholesterol) [ES = -0.25, 95% CI = -0.34 to -0.16, p 0.001];
-tumor necrosis factor-alpha serum levels [ES = -0.78, 95% CI = -1.39 to -0.16, p = 0.013];
-systolic blood pressure [ES = -1.72, 95% CI= -2.13 to -1.30, p 0.001];
-diastolic blood pressure [ES = -0.67, 95% CI = -0.96 to -0.37, p 0.001].
Significant means that there is an association with a 95% confidence.

The investigators found sensitivity analysis showed that the overall ESs did not change by excluding any individual meta-analysis.

The investigators found subgroup analysis revealed that the study population and type of dietary fiber could be partial sources of heterogeneity.

The investigators concluded that the present umbrella meta-analysis strongly support the beneficial effects of dietary fiber intake for the improvement cardiovascular risk factors, in particular cholesterol, fasting blood sugar, HbA1c, tumor necrosis factor-alpha and fasting insulin level, blood pressure and HOMA-IR value. However, it should be noted that the health-promoting effects of dietary fiber intake may differ between populations with different metabolic diseases.

Original title:
Associations between dietary fiber intake and cardiovascular risk factors: An umbrella review of meta-analyses of randomized controlled trials by Fu L, Zhang G, […], Tan M.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9511151/

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A high dietary fiber intake corresponds to a diet with at least 1.5 grams fiber per 100 kcal. Use the 7-points nutrition profile app to see if your daily diet contains 1.5 grams fiber per 100 kcal.
These products in the supermarket contain 1.5 grams fiber per 100 kcal.

An umbrella review article is a scientific article which only includes meta-analyses (also called review articles). The results found in an umbrella review article are more reliable than found in an individual review article.

One swallow does not make a summer. A famous Dutch saying that could not be any more obvious. Just because one single scientific study about a certain topic makes certain claims, it does not necessarily mean it is true. On the other hand, a review article (a collection of scientific studies on a certain topic) of randomized, placebo-controlled double blind clinical trials (RCTs) will answer the following question:
"Do taking dietary supplements make sense?" Yes for a positive conclusion and no for a negative conclusion.

One swallow does not make a summer. A famous Dutch saying that could not be any more obvious. Just because one single scientific study about a certain topic makes certain claims, it does not necessarily mean it is true. On the other hand, a review article (a collection of scientific studies on a certain topic) of (prospective) cohort studies or case-control studies will answer the following question:
"Should I change my diet?".

Objectives:
Several epidemiological studies have suggested that flavonoid intake is associated with a decreased risk of cardiometabolic disease. However, the results remained inconsistent and there is no dose-response meta-analysis for specific outcomes. Therefore, this review article has been conducted.

Is there a dose-response relationship between dietary flavonoid intake and reduced risk of cardiometabolic disease?

Study design:
This review article included 47 prospective cohort studies with a total of 1,346,676 participants and 127,507 persons with cardiometabolic disease.

Results and conclusions:
The investigators found for every 500 mg/d increase in dietary flavonoid intake a reduced risk of 7% [summary RR = 0.93, 95% CI = 0.88 to 0.98] for cardiovascular disease.
Significant means that there is an association with a 95% confidence.

The investigators found for every 500 mg/d increase in dietary flavonoid intake a reduced risk of 11% [summary RR = 0.89, 95% CI = 0.84 to 0.94] for diabetes.
Significant because summary RR of 1 was not found in the 95% CI of 0.84 to 0.94. Summary RR of 1 means no risk/association.

The investigators found for every 500 mg/d increase in dietary flavonoid intake a reduced risk of 3% [summary RR = 0.97, 95% CI = 0.94 to 0.99] for hypertension.
Significantly means it can be said with a 95% confidence that every 500 mg/d increase in dietary flavonoid intake really reduced risk of hypertension with 3%.

The investigators found a linearity dose-response association between total dietary flavonoid intake and cardiovascular disease [p nonlinearity = 0.541] and diabetes [p nonlinearity = 0.077].

The investigators concluded that a higher level of dietary flavonoid intake, at least 500 mg/d  is beneficial for the prevention of cardiometabolic diseases, particularly cardiovascular disease, diabetes and hypertension.

Original title:
Total dietary flavonoid intake and risk of cardiometabolic diseases: A dose-response meta-analysis of prospective cohort studies by Li T, Zhao Y, […], Liu J.

Link:
https://pubmed.ncbi.nlm.nih.gov/36148848/

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Cardiometabolic diseases are a group of common but often preventable conditions including heart attack, stroke, diabetes, insulin resistance and non-alcoholic fatty liver disease.

Objectives:
Findings of observational studies that evaluated the association of serum vitamin D status and high blood pressure were contradictory. Therefore, this review article has been conducted.

Does a high serum vitamin D concentration reduce risk of hypertension in the adult population?

Study design:
This review article included 10 prospective cohort, 1 nested case-control study and 59 cross-sectional studies.
Overall 66,757 and 260,944 participants were included in cohort and cross-sectional studies, respectively.
Among cohort studies, the NOS scores were between 6 and 9.
Among cross-sectional studies, the NOS scores ranged between 4 and 10.
There was no publication bias.

Results and conclusions:
The investigators found in the pooled analysis of cohort studies (66,757 participants) a 16% significant decrease in risk of hypertension in participants who had a high level of serum vitamin D compared with those with low level [pooled RR = 0.84, 95% CI = 0.73 to 0.96, I2 = 64%, p = 0.001].
Sensitivity analysis showed that excluding each stuy had no significant effect on pooled RR.

The investigators found combining effect sizes of 10 cohort studies involving a total of 63,602 individuals and 25,019 cases of hypertension showed that each 25 nmol/L increase in serum vitamin D level resulted in a 5% reduction in risk of hypertension [RR = 0.95, 95% CI = 0.90 to 1.00].
Also, a significant non-linear association between serum vitamin D levels and hypertension was observed [p non-inearity 0.001].
A reduction trend in risk of hypertension was observed for serum vitamin D levels between 45 and 70 nmol/L, although for higher vitamin D levels the risk did not decrease anymore and eventually started increasing.

The investigators found meta-analysis of cross-sectional studies showed that highest level of vitamin D in comparison to the lowest level was associated with a 16% significant decrease in risk of hypertension [OR overall = 0.86, 95% CI = 0.79 to 0.90, I2 = 67.5%, p 0.001].
Sensitivity analysis determined that the exclusion of each study did not significantly affect the overall estimate.

The investigators found combining effect sizes of 30 cross-sectional studies involving a total of 139,685 individuals and 40,178 cases of hypertension showed that each 25 nmol/L increase in serum vitamin D level resulted in a 6% reduction in risk of hypertension [OR = 0.94, 95% CI = 0.90 to 0.99].  

Also, a significant non-linear association between serum vitamin D levels and hypertension was seen [p non-linearity 0.001].
A reduction trend in risk of hypertension was observed for serum vitamin D levels between 40 and 75 nmol/L, although higher vitamin D levels did not reduce odds of hypertension.

The investigators concluded that serum vitamin D concentrations between 40 and 75 nmol/L reduce risk of hypertension in the adult population, in both prospective cohort and cross-sectional studies.

Original title:
Serum Vitamin D Levels in Relation to Hypertension and Pre-hypertension in Adults: A Systematic Review and Dose-Response Meta-Analysis of Epidemiologic Studies by Mokhtari E, Hajhashemy Z and Saneei P.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8961407/

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Objectives:
Dietary fats are one of the well-known stimulators of carotenoid absorption, but the effects of the quantity and the type of dietary fats on carotenoid absorption have not yet been studied systematically. Therefore, this review article has been conducted.

Do dietary fats improve the absorption of carotenoids?

Study design:
This review article included a total of 27 in vitro studies and 12 RCTs.

Results and conclusions:
The investigators found meta-regression of in vitro studies showed that the bioaccessibility of carotenoids, except for lycopene, was positively associated with the concentration of dietary fats.

The investigators found meta-analysis of RCTs showed that the bioavailability of carotenoids was enhanced when a higher quantity of dietary fats was co-consumed.

The investigators found, moreover, fats rich in unsaturated fatty acids resulted in greater improvement in carotenoid bioavailability [SMD = 0.90, 95% CI = 0.69 to 1.11] as compared with fats rich in saturated fatty acids [SMD = 0.27, 95% CI = 0.08 to 0.47].

The investigators concluded that co-consuming dietary fats, particularly those rich in unsaturated fatty acids, with carotenoid-rich foods can improve the absorption of carotenoids.

Original title:
Effects of dietary fats on the bioaccessibility and bioavailability of carotenoids: a systematic review and meta-analysis of in vitro studies and randomized controlled trials by Yao Y, Tan P and Kim JE.

Link:
https://pubmed.ncbi.nlm.nih.gov/34897461/

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Objectives:
Epidemiological studies indicate that higher intakes of flavonoids are associated with reduced stroke risk. However, which subtypes play significant roles to protect against stroke remain unclear. Therefore, this review article has been conducted.

Does dietary intake of different flavonoid subclasses (flavanones, flavan-3-ols) reduce risk of stroke?

Study design:
This review article included 10 independent prospective cohort studies with 387,076 participants and 9,564 events (persons with stroke).

Results and conclusions:
The investigators found higher intakes of flavanones significantly reduced risk of stroke with 15% [RR = 0.85, 95% CI = 0.78 to 0.93].

The investigators found dose-response analysis showed that 50 mg/day increment of flavanones dietary intake was significantly associated with 11% reduction in stroke risk [RR = 0.89, 95% CI = 0.84 to 0.94].

The investigators found dose-response analysis showed that 200 mg/day increment of flavan-3-ols dietary intake was significantly associated with 14% reduction in stroke risk [RR = 0.86, 95% CI = 0.75 to 0.98].

The investigators found no association with respect to other flavonoid subclasses.

The investigators concluded that both 50 mg/day flavanones and 200 mg/day flavan-3-ols dietary intake reduce stroke risk. The findings of these associations of the present study need to be confirmed in other regions and ethnic origins.

Original title:
A meta-analysis of prospective cohort studies of flavonoid subclasses and stroke risk by Li XQ, Wang C, […], Guo XF.

Link:
https://pubmed.ncbi.nlm.nih.gov/35023220/

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Objectives:
Oat supplementation interventions (OSIs) may have a beneficial effect on cardiovascular disease (CVD) risk. However, dietary background can modulate such effect. Therefore, this review article has been conducted.

Does dietary oat supplementation lower levels of blood lipids (cholesterol, triglycerides) and improve anthropometric parameters (glucose level, body mass index, weight, blood pressure, waist circumference) among participants with predominantly mild metabolic disturbances?

Study design:
This review article included 74 RCTs with a total of 4,937 predominantly hypercholesterolemic, obese subjects, with mild metabolic disturbances. Of these, 59 RCTs contributed to the meta-analyses.

The majority of included RCTs (81.1%) had some concerns for risk of bias.

Results and conclusions:
The investigators found oat supplementation (as oat, oat beta-glucan-rich extracts or avenanthramides), compared to control arms without oats, significantly improved levels of:
-total cholesterol (TC) [WMD = -0.42 mmol/L, 95% CI = -0.61 to -0.22];
-LDL cholesterol [WMD = -0.29 mmol/L, 95% CI = -0.37 to -0.20];
-glucose [WMD = -0.25 nmol/L, 95% CI = -0.36 to -0.14];
-body mass index [WMD = -0.13 kg/m², 95% CI = -0.26 to -0.01];
-weight [WMD = -0.94 kg, 95% CI = -1.84 to -0.05] and;
-waist circumference [WMD = -1.06 cm, 95% CI = -1.85 to -0.27].

The investigators found RCTs on inflammation and/or oxidative stress markers were scarce and with inconsistent findings.

The investigators found RCTs comparing an oat supplementation intervention to heterogeneous interventions (e.g., wheat, eggs, rice, etc.), showed lowered levels of glycated haemoglobin, diastolic blood pressure, HDL cholesterol and apolipoprotein B.

The investigators concluded dietary oat supplementation (as oat, oat beta-glucan-rich extracts or avenanthramides) may lower levels of blood lipids and improve anthropometric parameters among obese participants with predominantly mild metabolic disturbances, regardless of dietary background or control. May lower because the majority of included RCTs had some concerns for risk of bias. Therefore, further high-quality trials are warranted to establish the role of oat supplementation intervention on blood pressure, glucose homeostasis and inflammation markers.

Original title:
Effect of oat supplementation interventions on cardiovascular disease risk markers: a systematic review and meta-analysis of randomized controlled trials by Llanaj E, Dejanovic GM, […], Muka T.

Link:
https://pubmed.ncbi.nlm.nih.gov/34977959/

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These products are suitable for persons with cardiovascular diseases.