Summary: Eating 150 grams of blueberries a day can reduce the risk of cardiovascular disease by up to 15%.
Source: University of East Anglia
Eating a cup of blueberries a day reduces risk factors for cardiovascular disease – according to new research led by the University of East Anglia, in collaboration with colleagues from Harvard and across the UK.
New findings published today in the American Journal of Clinical Nutrition show that eating 150g of blueberries daily reduces the risk of cardiovascular disease by up to 15 per cent.
The research team from UEA’s Department of Nutrition and Preventive Medicine, Norwich Medical School, say that blueberries and other berries should be included in dietary strategies to reduce the risk of cardiovascular disease – particularly among at risk groups.
The team set out to see whether eating blueberries had any effect on Metabolic Syndrome – a condition, affecting 1/3 of westernised adults, which comprises at least three of the following risk factors: high blood pressure, high blood sugar, excess body fat around the waist, low levels of ‘good cholesterol’ and high levels of triglycerides.
Lead researcher Prof Aedin Cassidy, from UEA’s Norwich Medical School, said: “Having Metabolic syndrome significantly increases the risk of heart disease, stroke and diabetes and often statins and other medications are prescribed to help control this risk.
“It’s widely recognised that lifestyle changes, including making simple changes to food choices, can also help.
“Previous studies have indicated that people who regularly eat blueberries have a reduced risk of developing conditions including type 2 diabetes and cardiovascular disease. This may be because blueberries are high in naturally occurring compounds called anthocyanins, which are the flavonoids responsible for the red and blue colour in fruits.
“We wanted to find out whether eating blueberries could help people who have already been identified as being at risk of developing these sort of conditions.”
The team investigated the effects of eating blueberries daily in 138 overweight and obese people, aged between 50 and 75, with Metabolic Syndrome. The six-month study was the longest trial of its kind.
They looked at the benefits of eating 150 gram portions (one cup) compared to 75 gram portions (half a cup). The participants consumed the blueberries in freeze-dried form and a placebo group was given a purple-coloured alternative made of artificial colours and flavourings.
Co-lead, Dr Peter Curtis, said: “We found that eating one cup of blueberries per day resulted in sustained improvements in vascular function and arterial stiffness – making enough of a difference to reduce the risk of cardiovascular disease by between 12 and 15 per cent.
“The simple and attainable message is to consume one cup of blueberries daily to improve cardiovascular health.”
“Unexpectedly, we found no benefit of a smaller 75 gram (half cup) daily intake of blueberries in this at-risk group. It is possible that higher daily intakes may be needed for heart health benefits in obese, at-risk populations, compared with the general population.”
The research was led by the University of East Anglia in collaboration with The Harvard T.H. Chan School of Public Health, the University of Southampton, the University of Surrey, and the University of Cambridge. It was funded by the US Highbush Blueberry Council and the Biotechnology and Biological Sciences Research Council (BBSRC).
University of East Anglia
Lisa Horton – University of East Anglia
The image is in the public domain.
Original Research: Open access
“Blueberries improve biomarkers of cardiometabolic function in participants with metabolic syndrome—results from a 6-month, double-blind, randomized controlled trial”. Aedin Cassidy et al.
American Journal of Clinical Nutrition. doi:10.1093/ajcn/nqy380
Blueberries improve biomarkers of cardiometabolic function in participants with metabolic syndrome—results from a 6-month, double-blind, randomized controlled trial
Anthocyanin-rich blueberry intake is associated with reduced type 2 diabetes and cardiovascular disease (CVD) risk in prospective studies, although long-term randomized controlled trials (RCTs) have not been conducted in at-risk populations.
In the longest-duration RCT to date, we examined the effect of 6-mo blueberry intake on insulin resistance and cardiometabolic function in metabolic syndrome.
A double-blind, parallel RCT (n = 115; age 63 ± 7 y; 68% male; body mass index 31.2 ± 3.0 kg/m2) was conducted, which fed 2 dietarily achievable blueberry intakes [equivalent to 1/2 and 1 cup/d (75/150 g)] compared with matched placebo. Insulin resistance was assessed via the homeostasis model assessment of insulin resistance (primary endpoint) and confirmed by [6-6-2H2]-glucose-labeled, 2-step hyperinsulinemic clamp (n = 20). Clinically relevant cardiometabolic endpoints [including flow-mediated dilatation, augmentation index, lipoprotein status (by nuclear magnetic resonance spectroscopy), and nitric oxide (NO)-related metabolite assay] and anthocyanin metabolism were assessed.
A daily intake of 1 cup of blueberries improved endothelial function (flow-mediated dilatation: +1.45%; 95% CI: 0.83%, 2.1%; P = 0.003), systemic arterial stiffness (augmentation index: –2.24%; 95% CI: –3.97%, –0.61%; P = 0.04) and attenuated cyclic guanosine monophosphate concentrations. In statin nonusers (n = 71), elevated high-density lipoprotein cholesterol (+0.08 mmol/L; P = 0.03), high-density lipoprotein particle density (+0.48n, ×10–6; P = 0.002) and apolipoprotein A-I (+0.05 g/L; P = 0.01) concentrations were observed following the 1-cup/d intervention. Treatment compliance was 94.1% (wrapper returns) and total concentrations of anthocyanin-derived phenolic acid metabolites significantly increased, dose-dependently, in serum and 24-h urine (P < 0.01 and P < 0.001, respectively). Insulin resistance, pulse wave velocity, blood pressure, NO, and overall plasma thiol status were unaffected. Likewise, a half cup per day had no effect on any biomarkers.
Despite insulin resistance remaining unchanged we show, to our knowledge, the first sustained improvements in vascular function, lipid status, and underlying NO bioactivity following 1 cup blueberries/d. With effect sizes predictive of 12–15% reductions in CVD risk, blueberries should be included in dietary strategies to reduce individual and population CVD risk. This study was registered at clinicaltrials.gov as NCT02035592.