Since writing ‘Ergogenic aids – is it possible to boost performance with food?’ in May, I have already added almonds to the list of foods that are thought to give a boost to performance. I can now add another, blackcurrants. The University of Chichester have recently announced some very interesting results, looking at the effect of using a concentrated blackcurrant supplement on sporting performance. After just seven days taking the NZ blackcurrant supplement, healthy male and female triathletes were found to have significantly better blood lactic acid readings and cycle time trial performance (8).

Why is lower lactic acid an advantage?

Commonly the term “lactic acid buildup” is used by athletes to describe the intense pain felt during exhaustive exercise and was until recently widely thought to be the cause of next day muscle stiffness, though this has now been disproved.

Lactic acid is produced during anaerobic respiration and begins to accumulate in the muscles when the athletes work-rate is above the anaerobic threshold. Generally accepted as being at 80-90% of the maximum heart rate, the anaerobic threshold occurs when insufficient oxygen is being delivered to the working muscles for aerobic respiration to be effective. In the absence of oxygen the Krebs Cycle can not be completed and free hydrogen combines with pyruvic acid forming lactic acid. Lactic acid build-up causes a burning feeling in the muscles and increased acidity in the blood, hampering the delivery of glucose. High levels of lactate and associated hydrogen ions are therefore detrimental to performance.

Improving your lactate acid threshold.

An individuals anaerobic threshold is also known as their lactate acid threshold, i.e. when the time when lactic acid begins to build up. If your lactate acid threshold is reached quickly and during low intensity exercise, it generally means your energy systems are not working well. This may be because you are not as fit as you could be and are not getting enough oxygen to the muscle cells but it can have other causes. Endurance training improves an individuals lactate or anaerobic threshold, developing greater aerobic capacity and improving the cells alkaline buffering ability.

What does NZ Blackcurrant supplementation do?

Researchers at Chichester have found that taking blackcurrant supplements appears to increase an individuals lactate acid threshold as well as improving lactic acid breakdown and clearance from the muscle. Over-all this resulted in an around 3% improvement in cycling time trial performance, but in some individuals the improvement was as high as 8.6%. The active ingredient in the blackcurrants is thought to be the phytonutrient anthocyanins. All blackcurrants are a good source of anthocyanin but NZ blackcurrant are proclaimed as a particularly good source of the four major anthocyanin compounds. Anthocyannins from NZ blackcurrants have also been associated with decreased lung inflammation and improvement in symptoms of asthma (1) improvement in peripheral blood flow (2) and circulation (3) in humans and vasorelaxation / vasodilation in animal studies (4).

Anthocyanins and proanthocyanidins found in blackcurrants have also been found to inhibit α-glucosidase activity and intestinal glucose uptake  (5,6), slowing the glycemic response of a high sugar meal.

 New Zealand Blackcurrants

According to research completed in New Zealand, NZ blackcurrant cultivars have higher anthocyanin and polyphenol levels when compared to blackcurrants from other sources. The New Zealand Institute for Crop and Food Research (CFR) found that the anthocyanin content of European blackcurrants is 250-500mg per 100g (average) whereas the content in NZ blackcurrants is nearer, 570mg per 100g (average). Ben ard and Ben Rua, blackcurrant species unique to New Zealand, are high yielding varieties grown on a large commercial scale and NZ research has found they have approximately 25% higher anthocyanin levels than blackcurrants from Poland, Canada, Scotland and Sweden.

Anthocyanin content by country (source Just Berry PD Corp) (5)

Who is using blackcurrants ?

The research is very new and further trials are needed but Surrey Cricket Club have announced that they have been using CurraNZ, the supplement tested at Chichester, since March. The club’s strength and conditioning coach and nutritionist, Ryan Blake has been quoted saying “CurraNZ is ideal for players given the high physical demands they face in professional cricket.”

ADVICE

Anthocyanins are found in many other fruit and vegetables as well as blackcurrants and many of these have already been hailed as super-foods. The Chichester research has only looked at blackcurrant and more specifically at a NZ Blackcurrant supplement made by CurraNZ and it is not yet known if these findings are specific to something in these specific berries or can be seen with all blackcurrants or all sources of specific anthocyanins. Other good sources of anthocyanin are aubergine, plums, purple asparagus, cranberries, blueberries, blackberries, red cabbage, black grapes and cherries. It is likely that the amount needed to see an effect may make getting enough from the diet difficult and the skin is almost certainly the best source. Jam maybe a good alternative to supplements being a concentrated source and there is some research  suggesting anthocyanin absorption may be improved by glucose content (9).

Anthocyanin content is also known to be higher in plants grown on poor soil and where the conditions are harsh. Content is known to vary significantly between plants and years.

All fruits and vegetables contain beneficial phytochemicals. NHS and world health organisation advice is to eat as many different fruit and vegetables as possible including as many different colours. Eating a few more blackcurrants certainly won’t hurt.