Full Disclosure: ‘ have partnered with CurraNZ (www.curranz.co.nz), the blackcurrant health & fitness supplement company to do a series of blog posts on the science behind the benefits of NZ blackcurrants. This content is sponsored to the extent that CurraNZ has paid for my time to review the research, the copy/opinions here are my own.
Cardiovascular disease is one of the biggest contributors to early mortality worldwide, and New Zealand is not exempt from this. Conditions that increase the risk of cardiovascular disease are themselves leading to poor quality of life and poorer health outcomes, including hypertension, insulin resistance and type 2 diabetes.
Blackcurrants are a major source of anthocyanins, a polyphenol that is part of the flavonoid group. They contain significant amounts of proanthocyanins, which have been studied for the effects they may exert on blood pressure and our vascular system. There have been some promising results from clinical trials that suggest blackcurrant extract supplements may well form part of the diet and lifestyle approach that is required to improve health outcomes associated with metabolic disease. Indeed, arterial blood flow improvements of up to 45% have been found in clinical trials administering the extract, which is important for overall vascular health.
In trials that examine the impact of blackcurrants on blood pressure, doses of 210mg of the anthocyanins (equating to two 300mg blackcurrant capsules) significantly decreased blood pressure in older adults, particularly in those that had higher than normal blood pressure to start with. The effect is dose and time dependent, with smaller amounts and a single dose administration having no impact acutely. Studies with significant results are those that span 7 days, suggesting it is the build-up of the anthocyanins in the bloodstream that exerts a favourable vascular effect. Further cardiovascular benefits have been seen in similar cohort of people, with (in addition to blood pressure improvements) reduced arterial stiffness in carotid and femoral arteries and improvements in blood flow and overall vascular health was found with a 7-day protocol using the same dose of the blackcurrant extract. These finding warrants attention given how important arterial health and blood flow is for cardiovascular health and reducing the impact of ageing on vascular function. Interestingly, a dosing protocol over 14 days, where participants took the supplement every other day (as opposed to every day) also revealed a favourable impact, with lower diastolic blood pressure and mean arterial pressure. While there is limited research investigating the intermittent dosing protocol, this is a promising strategy for people who may not be able to take a daily dose of the supplement.
Blackcurrant extract (when administered before a meal in amounts of 600mg) has also been found to significantly lower blood glucose and insulin response to a high carbohydrate meal in healthy adults. Avoiding those exertions in blood sugar is essential, even in healthy adults as one of the underlying causes of insulin resistance is the roller coaster effect of a meal that results in the peaks and troughs in blood sugar. Too high and there is increased oxidative stress and damage, and too low there is a stress response in the body that increases stress hormones impacting on levels of inflammation, food cravings and subsequent food decisions. Over the long term, these exertions can result in insulin resistance and progress to metabolic syndrome, type 2 diabetes and cardiovascular disease. Controlling overall blood sugar is critical to optimising health and minimising overall disease risk.
The lifestyle behaviours that help minimise risk of insulin resistance, type 2 diabetes and cardiovascular disease all aim to improve blood flow, control blood sugar, reduce inflammation and arterial stiffness in an effort to delay the ageing process. Blackcurrant extract appears to be a worthwhile addition to the toolbox for those keen to do what they can to minimise their risk.
Mikki Williden, PhD 