Purple Passion!

There is a wealth of information on what we should eat to optimise our health and longevity, and some of that information is conflicting.  

What is never in conflict though is the need to eat a wide range of fruit and vegetables – we need to “eat the rainbow” for optimal health and while we don’t really believe in “superfoods” we are a big fan of the colour PURPLE!

We get excited about the colour PURPLE because purple to us means anthocyanins – which means a whole bunch of things for our health.

Anythocyanins are the plant compounds that make plants purple – purple leaves or purple fruit are caused by the presence of a wide range of anthocyanin compounds. 

The purple colour has an important biological function for the plant of attracting pollinators and seed dispersers and defending against stressors.  One of the stressors the anthocyanins protect plants from is high UV light – which is why New Zealand plants have higher levels of anthocyanins than plants grown in other parts of the world – in fact a study on New Zealand blackcurrants showed they had 1.5 X the levels of anthocyanins as the same cultivars grown in North America (listen to more about the study here ).

In plants, anthocyanins help to mitigate photooxidative injury (that’s injury from too much light) by efficiently scavenging free radicals and reactive oxygen species. It is those same functions which are very useful for human health – more on that in a minute.

Cold weather also triggers anthocyanin production in plants – again for the protective effect – that’s why you often see the very intense purple colours in the cooler seasons.

The more we read about anthocyanins, the more we shake our heads in wonder – we eat all this awful, processed food made from processed grains and preservatives when we could be treating ourselves to this rainbow of plants with all the corresponding health benefits.

Is a coincidence that what is good for plants is good for humans?

Is it a coincidence that our bodies are so dependent on plants for good health and medicine?  Morphologically, Australopithecus africanus, a hominid that lived around three million years ago had stronger jaws to cope with tougher plant food than we do now, they chewed on the uncooked underground storage organs of plants.  Later, Homo erectus is believed to have foraged on the savannah for grasses and grass seeds, which are a better food source than the plants eaten by Australopithecus, and less difficult to digest – resulting in a change to the jawline and less thick enamel on their teeth.

Interestingly, morphology is not the only thing to have changed over time - one of the most important biochemical pathways in plants is the shikimic acid (SA) pathway, through which plants biosynthesise three of the nine essential amino acids that are not produced in the human body. Humans have evolved to require derivatives of the SA pathway, and therefore to depend on plants for optimal health.

The SA pathway also provides us with flavonoids and alkaloids, many of which are used as medicines; for example, star anise (Illicium verum) and sweetgum (Liquidambar styraciflua) are sources of SA as the basis for Tamiflu, which is used to prevent symptoms of influenza.

Is it possible the anthocyanin pathway is another biochemical pathway that humans have co-evolved to take advantage of?  We don’t know, but we have summarised some of the scientific studies about anthocyanins below, with their links, if you would like to read further. 

In these links you can read about how anthocyanins influence brain health, lung health and heart health.

It all adds up to us loving the colour PURPLE!

Boysenberries

• Boysenberry consumption significantly reduces airway inflammation through decreased cell infiltration and mucus production;
• Boysenberry consumption reduces collagen deposition from chronic inflammation and assists in the repair of damaged tissue by supporting fibrolytic M2 macrophages
• Boysenberry consumption prophylactically prevents airway inflammation.
• Boysenberry consumption prophylactically prevents airway inflammation.

Potential modes of action by boysenberry bioactive molecules are summarised below:

• Reduce immune cell infiltration and mucus over secretion via anthocyanin cyanidin-3-Oglucoside modulating the IL-4Rα-STAT6 signaling pathway (Ma et al., 2019);
• Cyanidin acts as an agonist (activator) for peroxisome proliferator-activator receptor (PPAR)-γ (Jia et al., 2013);
• This may increase numbers and activity of M2 fibrolytic macrophages, thereby helping with removal of inappropriately deposited collagen;
• The procyanidins epicatechin (EC) and epigallocatechin (EGC) inhibit TNF-α NFκB signalling to reduce CCL11 eosinophil recruitment (Sawyer et al., 2017, Coleman et al., 2016a);
• Procyanidins also potentially inhibit IL-4/IL-13 signaling through receptor internalisation, membrane polarisation and/or affecting the redox potential of the cell which decreases inflammatory signaling pathways.

Blackcurrants

• Blackcurrants have been shown to reduce inflammation in asthmatics. Blackcurrant anthocyanins attenuated OVA-induced airway inflammation, eosinophilia, and CCL11 production in a murine asthma model.  Similarly, higher levels of IL-17 in asthmatic patients have been shown to stimulate neutrophil-mobilizing cytokines such as IL-6 and -18 through MAPK and NF- k B pathways (Shaw, et al., 2017, Kim, H et al,. 2011). 
• Blackcurrants support a healthy vascular system in older adults. Carotid-femoral pulse-wave velocity, an index of central arterial stiffness, and central blood pressure were measured at baseline and again at the end of the 7-day study period.  Carotid-femoral pulse-wave velocity and central blood pressure decreased significantly after the 7-day study period with blackcurrant intake. In addition, carotid-femoral pulse-wave velocity and central blood pressure in the blackcurrant intake trial decreased significantly more than in the placebo intake trial (Okamoto et al., 2020).
• The anthocyanins found in blackcurrants, according to in vitro and in vivo experiments with animals, as well as several epidemiological or clinical studies in humans, have been demonstrated to be effective in protection of the heart against ischemia/reperfusion-induced injury and in reduction of mortality related to cardiovascular diseases (T.L. Zern, et al., 2005, A. Cassidy, et al., 2013, Cassidy, et al., 2015, Mink et al., 2007, Scarabelli et al., 2009, Toufektsian, et al., 2008, Wang, et al., 2014, Zern, et al., 2005).
• New Zealand Blackcurrants were shown to increase VO2 max, and the total running distance of elite athletes by 10.6%. Also, as greater distances were covered with repeated sprints, there was 15% higher lactate at exhaustion, and larger changes in lactate during early recovery after repeated sprints to exhaustion when blackcurrant was consumed (Perkins, I. C. et al., 2015 ).