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27th April 2022
A higher avocado intake reduces the risk of cardiovascular disease according to the findings from two large prospective studies reported by researchers from Harvard T.H. Chan School of Public Health, Boston, USA.
Cardiovascular disease (and which also includes coronary heart disease) represents the leading cause of death globally. Interestingly, studies suggest that there is a valid association between several dietary factors and patterns with coronary heart disease. One healthy food is avocado, which contains a large amount (71%) of monounsaturated fatty acids and helps to promote healthy blood lipid profiles, enhancing the bioavailability of fat soluble vitamins and phyto-chemicals from the avocado or other fruits and vegetables. In fact, there are data showing how avocado consumption is associated with a reduced risk of metabolic syndrome and other work has indicated that eating at least one avocado each day provides a beneficial effect on cardio-metabolic risk factors that extended beyond their heart-healthy fatty acid profile. Furthermore, a recent systematic review found that avocado intake increased serum HDL-cholesterol concentrations, prompting the authors to suggest that the association between avocado intake and cardiovascular risk should be confirmed by well-conducted prospective observational studies or long-term trials.
For the present study, the US team examined the association between a higher avocado intake and cardiovascular outcomes. They turned to data held in both the Nurse’s Health Study (NHS) and the Health Professionals Follow-up Study (HPFS), which are two prospective cohort studies which were initiated in the 1970’s and 1980’s respectively. In both of these cohort studies, participants were asked to complete validated questionnaires asking about lifestyle and diet every 2 years and from this information, the researchers were able to determine how much avocado was consumed. This was then categorised as never or less than once a month, 1 – 3 times per month, weekly and > twice a week. The primary outcome of interest was incident cases of total cardiovascular disease, which was a composite of several adverse cardiovascular outcomes e.g., fatal coronary heart disease. The main secondary outcome related to strokes.
Higher avocado intake and adverse cardiovascular outcomes
A total of 68,786 women from the NHS and 41,701 men from the HPFS who were free of cardiovascular disease and stroke at baseline were included and followed for 30 years (median for men was 13.3 years and 14.2 for women). During follow-up there were a total of 14,274 cases of cardiovascular disease (CVD) in both NHS and HPFS.
After adjustments were made for dietary and lifestyle factors, compared to those who did not eat avocados, individuals with a higher avocado intake (> twice/week) week had a 16% lower risk of CVD (hazard ratio, HR = 0.84, 95% CI 0.75 – 0.95) and a 21% lower risk of coronary heart disease (HR = 0.79, 95% CI 0.68 – 0.91). However, there was no significant reduction for stroke.
The authors calculated that for each half serving/day increase in avocado intake, the pooled hazard ratio for CVD was 0.80. In fact, the authors added that by replacing half a serving/day of margarine, butter, egg, yoghurt, cheese or processed meats with the equivalent amount of avocado would be associated with a 16 to 22% lower risk of CVD.
Pacheco LS et al. Avocado Consumption and Risk of Cardiovascular Disease in US Adults J Am Heart Assoc 2022
11th April 2022
Coffee intake (whether ground or instant) of at least 2 – 3 cups per day has been found to be associated with significant reductions in the risk of developing cardiovascular disease (CVD), arrhythmias, as well as cardiovascular and all-cause mortality. This is according to the findings of three studies analysing data held within the UK Biobank.
Although coffee contains caffeine, it is also a rich source of phenolic compounds including chlorogenic acids which contribute to coffee’s antioxidant activity. Moreover, coffee intake at midlife has been associated with a lower risk of dementia and Alzheimer’s disease compared with those drinking no or only little coffee. However, the cardiovascular benefits from drinking coffee are less clear with one study finding that in men, the risk of nonfatal myocardial infarction was not associated with coffee drinking. In contrast, a large prospective study observed that coffee consumption was inversely associated with total and cause-specific mortality.
Due to these conflicting results, three studies presented at the American College of Cardiology Scientific Session have examined cardiovascular and mortality benefits disease associated with coffee intake.
In the first study, effects of habitual coffee consumption on incident cardiovascular disease, arrhythmia, and mortality: findings from UK BIOBANK, researchers from the University of Melbourne, Australia, included data from 382,535 individuals with a mean age of 57 years (52% female) and assessed the effect of coffee intake over a 10-year period. The results showed that a coffee intake of 2 – 3 cups/day was significantly associated (for all associations, p < 0.01) with the lowest risk for developing CVD (Hazard ratio, HR = 0.91, 95% CI 0.88 – 0.94), coronary heart disease (HR = 0.90), heart failure (HR = 0.85) and all-cause mortality (HR = 0.86). They found a U-shaped relationship between higher coffee intake and incident arrhythmia which was also lowest at 2 – 3 cups/day (HR = 0.92).
In the second study, regular coffee intake is associated with improved mortality in prevalent cardiovascular disease, the Australian team focused on the effect of coffee in patients with existing cardiovascular disease. With a population of 502,543 individuals, again followed for 10 years, CVD was subsequently diagnosed in 342,279 participants, of whom, 19.6% died. The team found that coffee intake was safe at all levels and that survival was improved again at 2 – 3 cups/day (HR = 0.92, 95% CI 0.86 – 0.99, p = 0.03). Among 24,111 participants diagnosed with an arrhythmia, drinking only one cup of coffee per day was associated with the lowest mortality risk (HR = 0.85) and specifically in those with atrial fibrillation or flutter, one cup of coffee per day was associated with improved survival (HR = 0.82, p < 0.01).
In the third study, ground, instant or decaffeinated coffee? Impact of different coffee subtypes on incident arrhythmia, cardiovascular disease and mortality, the team wondered if there were any differential cardiovascular benefits depending on how the coffee was prepared. Overall, they found that drinking between 1 and 5 cups of coffee per day were associated with a reduced risk of arrhythmia, CVD, CHD, heart failure and stroke. The greatest reduction in risk for CVD was seen with drinking 2 – 3 cups/day of ground coffee (HR = 0.83, 95% CI 0.79 – 0.87) but there was still a significant, albeit smaller, reduction in risk from consuming instant coffee (HR = 0.91, 95% CI 0.88 – 0.95).
Finally, in the third study, the authors showed that drinking 2 – 3 cups/day of decaffeinated coffee was associated with a mortality benefit (HR = 0.85, 95% CI 0.80 – 0.91, p < 0.01), leading the authors to conclude that non-caffeine compounds within coffee are likely to be important factors associated with greater survival among coffee drinkers.
Given these findings, the authors suggested that coffee intake should be considered as part of a healthy diet.
24th March 2022
The use of a cocoa extract containing flavanols did not reduce the overall incidence of cardiovascular events but did lower the incidence of cardiovascular deaths. This was the main finding of a randomised trial by researchers from the Division of Preventive Medicine, Brigham and Women’s Hospital, Boston, US.
Flavan-3-ols, which are a subclass of flavonoids, represent a type of poly-phenolic substances which are present in a range of plants such as cocoa and cocoa containing foods such as chocolate. Furthermore, research demonstrates a beneficial effect of cocoa on blood pressure, insulin resistance, and vascular and platelet function. As well as flavonoids, a cocoa extract typically contains other ingredients such as epicatechin and the methylxanthines, theobromine and caffeine. In fact, studies suggest how the presence of these latter components mediate an increased plasma concentration of epicatechin metabolites that coincides with enhanced vascular effects. To date, much research which has focused on the cardiovascular effect of cocoa containing products such as chocolate, and suggests a small inverse association between consumption and both coronary heart disease and stroke. However, there is a lack of data from large-scale trials, on the cardiovascular benefits of a flavanol-rich cocoa extract which contains all the bioactive compounds present in the cocoa bean.
As a result, the US team undertook the Cocoa Supplement and Multivitamin Outcome Study (COSMOS), a pragmatic, randomised trial which sought to examine the effect of a cocoa extract on cardiovascular disease and cancer in older adults. For the present study, the authors have only reported on the cardiovascular outcomes.
The team recruited adults over 65 years of age, who were initially free of major cardiovascular disease and given either a cocoa extract containing 500 mg/day of cocoa flavanols and a multivitamin supplement or matching placebo. All participants were required to stop taking cocoa supplements (although chocolate could still be eaten) and a blood biomarker of flavanol intake were initially measured and repeated after years 1, 2 and 3. The primary outcome was a composite of total cardiovascular disease (CVD) outcomes including myocardial infarction (MI), stroke, cardiovascular mortality and coronary revascularisation. The authors then set the secondary outcomes as the individual components of the primary outcome, i.e., cardiovascular death, stroke etc.
Cocoa extract and cardiovascular outcomes
A total of 21,442 individuals with a mean age of 72.1 years (59.1% female) were randomised to cocoa (10,719) or placebo and followed for a median of 3.6 years. Based on an analysis of plasma samples, there was a three-fold higher increase compared to placebo, in the levels of flavanol biomarker and this did not differ between follow-up assessment.
During the follow-up period there were 866 confirmed cardiovascular events, 410 in those taking the cocoa extract and 456 in the placebo group, giving a hazard ratio, HR of 0.90 (95% CI 0.78 – 1.02, p = 0.11).
For the secondary outcomes, only cardiovascular death was significantly different (HR = 0.73, 95% CI 0.54 – 0.98).
The authors concluded that while the cocoa extract did not reduce the primary outcome, longer follow-up of trial participants may further elucidate the relationship between consumption of the extract and cardiovascular events.
Sesso HD et al. Effect of Cocoa Flavanol Supplementation for Prevention of Cardiovascular Disease Events: The COSMOS Randomized Clinical Trial Am J Clin Nutr 2022
18th February 2022
The cardiovascular disease burden among those who survived an infection with COVID-19 appears to be huge and present even for those not originally hospitalised during the acute phase of their infection. This is according to a study by researchers from the Clinical Epidemiology Center, Research and Development Service, Missouri, US.
Studies among patients who were originally hospitalised because of a COVID-19 infection have found higher rates of subsequent cardiovascular disease. In fact, it has been found that COVID-19 is a risk factor for acute myocardial infarction and ischaemic stroke. However, many of the studies linking infection with COVID-19 and subsequent adverse cardiovascular outcomes relate to patients who were originally hospitalised because of their infection. As a result, these individuals might have had a number of co-morbidities that increased their cardiovascular disease risk burden. In the absence of a comprehensive assessment of the cardiovascular effects of COVID-19 at 12 months and among individuals treated in different care settings, the authors of the current study, set out to address this important knowledge gap.
The team used the US department of Veterans Affairs national healthcare databases to build a cohort of individuals who had survived for at least 30 days after an acute COVID-19 infection and two other groups; one consisting of Veterans Affairs members with no evidence of a COVID-19 infection and a historical cohort (i.e., prior to the current pandemic) from 2017. The researchers followed these three cohorts to estimate the risks of pre-specified incident cardiovascular outcomes and further analysed these outcomes with respect to the existence of prior cardiovascular disease and according to their particular care settings.
Cardiovascular disease burden and COVID-19
The overall sample included 153,760 individuals with a mean age of 61.4 years (89% male) who had COVID-19, 5,637,647 contemporary controls and 5,859,411 historical controls. All three groups were followed for a median of 347.3 days.
Among those with COVID-19, there was a 52% increased risk of stroke (hazard ratio, HR = 1.52, 95% CI 1.43 – 1.62) compared to contemporary controls and a 49% increased risk of a transient ischaemic attack (HR = 1.49). Increased risks were also found for dysrhythmias including atrial fibrillation (HR = 1.71) and sinus tachycardia (HR = 1.84) and thromboembolic disorders such as a pulmonary embolism (HR = 2.93) and deep vein thrombosis (HR = 2.09).
The authors then used the composite endpoint of major adverse cardiovascular events (MACE) which included myocardial infarction, stroke and any of the pre-specified outcomes. Compared to the contemporary control group, the risk of MACE was 55% higher (HR = 1.55) and for any cardiovascular outcome (HR = 1.63).
The cardiovascular disease burden after a COVID-19 infection was also higher than for contemporary controls among those who did not have prior cardiovascular disease. Furthermore, these risks were still elevated, compared to those in the contemporary group, irrespective of the care setting where patients were treated, e.g., non-hospitalised, hospitalised and intensive care .
The authors concluded that their study had demonstrated a substantial cardiovascular disease burden among those who had experienced an acute infection with COVID-19, even among those without prior disease and in any care setting in comparison to those without an infection.
Xie Y et al. Long-term cardiovascular outcomes of COVID-19 Nat Med 2022
26th January 2022
SGLT2-Is can be considered as an effective class of drugs to improve cardiovascular morbidity and mortality. This was the conclusion of a meta-analysis by researchers from the Division of Cardiology, Southern Illinois University School of Medicine, US.
SGLT2-Is were developed and licensed as a class of drugs for the management of type 2 diabetes and one agent in particular, dapagliflozin, has been shown, as an add-on drug to conventional anti-diabetic drugs, to improve glycaemic control. However, with more widespread use of these drugs, it became apparent that there were potential cardioprotective effects, such as a reduction in the worsening of heart failure, irrespective of whether or not the patients were diabetic.
For the present study, the US researchers, set out to establish whether the magnitude of any cardiovascular benefit from SGLT2-Is were generalisable to patients of different ages and ethnicities. They searched for placebo-controlled randomised clinical trials in patients with existing atherosclerotic cardiovascular disease (ASCVD) or the presence of risk factors for ASCVD such as diabetes or heart failure. They set the primary outcome as cardiovascular death or hospitalisation for heart failure (HHF) and major cardiovascular events (MACE), HHF, cardiovascular death, acute myocardial infarction and all-cause mortality as secondary outcomes. They included gender, age (< 65 or > 65) and ethnicity as subgroups for separate analyses.
A total of 10 trials including 71,553 patients were analysed with 39,053 who received SGLT2-Is.
The primary outcome of cardiovascular death or HHF was reported in all trials and there were 6921 incidents, 8.1% occurring in those given SGLT2-Is and 11.6% in the placebo group. The use of SGLT2-Is was calculated to be associated with 33% reduced risk of the primary outcome (odds ratio, OR = 0.67, 95% CI 0.55 – 0.80, p < 0.01).
There was also a reduced risk of MACE in those taking SGLT2-Is (OR = 0.90, 95% CI 0.81 – 0.99, p = 0.03). However, there was no difference in the rate of acute myocardial infarction in those taking SGLT2-Is compared to placebo (OR = 0.95, 95% CI 0.87 – 1.03). Moreover, subgroup analysis favoured the use of SGLT2-Is in all groups compared and all-cause mortality was also lower in those taking SGLT2-Is (OR = 0.87, 95% CI 0.80 – 0.96, p = 0.04).
The authors concluded that the ‘cardiovascular outcomes of SGLT2-I therapy can be compared across all trials, and it demonstrates remarkable consistency of class benefit, despite the variations in populations enrolled.’
Bhattarai M et al. Association of Sodium-Glucose Cotransporter 2 Inhibitors With Cardiovascular Outcomes in Patients With Type 2 Diabetes and Other Risk Factors for Cardiovascular Disease: A Meta-analysis. JAMA 2022