Why chocolate can be a health food…
I’m not usually one to fall prey to the superfood trend but cacao truly is something I cannot live without.
Chocolate has gotten an unfair bad rap, from claims that it causes weight gain to acne. However, it is not the cacao or the cocoa that causes the problem, it is the junk that normally goes into it like sugar, dairy, and additives.
There is a growing body of research that shows cacao may confer anti-inflammatory benefits, support brain and heart health, support healthy blood sugar control, supports our immune system and our skin health. 
The reason is that it is very nutrient-dense e.g. it is a good source of zinc, important for immune function, skin and hormonal health. It also contains other key minerals like magnesium, potassium and iron which are vital for physiological functions throughout the body.
The superstar, however, is perhaps a family of antioxidants called flavonoids.
Flavonoids are a large family of over 5000 compounds found in fruits and vegetables, but also in plant products such as tea, cacao and wine.
Since the 1990s, there has been growing interest and research in flavonoids because they exhibit anti-inflammatory, antithrombogenic, antidiabetic, anticancer, and neuroprotective activities through different mechanisms of action in vitro and in animal models 
There are 6 subclasses of flavonoids as demonstrated in this chart:
(source:Linus Pauling Institute at the Oregon state University, https://lpi.oregonstate.edu/mic/dietary-factors/phytochemicals/flavonoids)
Cocoa components are particularly rich in catechins: mainly monomeric (−) epicatechin and (+) catechin, as well as oligomeric and polymeric proanthocyanidin flavanols. However, in smaller amounts, gallocatechin and epigallocatechin, have also been quantified 
Different flavonoids can help the body in different ways.
Some flavonoids have been recognized for their antimicrobial activity and many researchers have isolated and identified in vitro (in petri dish studies) the structures of flavonoids having properties of antifungal, antiviral and antibacterial activity. Because of this property, many flavonoids being used are extensively researched in the fields of nutrition, food safety and health.
The antiviral effect of flavonoids has been shown by Wang et al. , particularly in therapy against viral infections. Flavonoids such as quercetin, naringin, hesperetin and catechin possess a variable degree of antiviral activity. They may affect the replication and infectivity of certain RNA and DNA viruses. Quercetin and apigenin are among the most studied flavonoids which have been known to exhibit antibacterial activities 
In a study by Lu & Chong  computational work was carried out to predict the binding modes of 20 flavonoid derivatives with the enzymes of the 2009 haemagglutinin 6 (H1N1) influenza virus. All twenty flavonoid derivatives were found to be satisfactory in binding and inhibiting the activity of the virus. These findings may help to develop a potential drug form of the flavonoid derivatives for the treatment of H1N1 influenza disease. More research is needed, because we cannot simply extrapolate what we observe from in vitro studies to humans, however, this is a promising area of research. The caveat to this is that sugar has been shown  to impair immune cell functions for up to 4 hours after consumption, so the addition of large amounts of refined sugar in chocolate may mitigate some of the antimicrobial effects.
Another superstar in cacao that not many people talk about is Resveratrol. Resveratrol is a polyphenol which most associate with red wine but in fact, it is also found in cacao  and depending on the quality, 1 tbsp of cacao may contain comparable amounts to 1 glass of wine (the concentration of resveratrol in foods depend on geographic location, how it is grown and processed after harvest. The Santa Barbara…… please insert your lab readings and the name of your chocolate tested here).
(source: Linus Pauling Institute at Oregon State University https://lpi.oregonstate.edu/mic/dietary-factors/phytochemicals/resveratrol#food-sources)
Resveratrol has been shown in studies to have powerful antioxidant and anti-inflammatory activities. It has been shown in vitro and animal studies to inhibit cancer cell growth , associated with benefits for cardiovascular health , and cognitive function 
One of the ways resveratrol has been proposed to effect health benefits is by down-regulating the NLRP3-inflammasone pathway . Inflammasones are protein complexes inside the cell which are activated in response to a negative stimuli e.g. an infection, in order to mount an inflammatory process which deals with the insult. Appropriate activation of this cascade helps us overcome these acute events and ideally, the inflammasone is switched off after we have dealt with the event successfully.
The persistent activation of this inflammasone has been implicated in many chronic diseases such as type 2 diabetes, atherosclerosis, and neurodegenerative diseases. And more recently, the activation of the NLRP3 inflammasone has been implicated as a contributor in the cytokine storm some patients with Covid19 unfortunately experiences. The cytokine storm is responsible for the acute respiratory distress syndrome and multi-organ failure witnessed in some covid19 cases, therefore, a few of the treatments being trialled right now include modalities to block the hyper-inflammatory response.
Nothing as yet has been proven to prevent or treat covid19, however, an in vitro study looking at MERS-CoV using cell lines demonstrated that ‘resveratrol significantly inhibited MERS-CoV infection and prolonged cellular survival after virus infection’  (note-MERS-CoV is a different strain of the coronavirus so more research is needed to know if this petri-dish finding translates to human clinical benefits and also if it can be translated to other coronaviruses like covid-19, more research is needed).
The most known about benefit is perhaps the potential effect on cardiovascular health. A recent meta-analysis of 14 prospective studies published between 1996 and 2012 reported that higher intakes in each flavonoid subclass were significantly associated with a reduced risk of cardiovascular events, and for every for every 10 mg/d increment in flavonol intake, there was a 5% reduction in the risk of cardiovascular disease. .
This is perhaps related to the effect flavonoids have been demonstrated to have on endothelial function. The endothelium is the lining of our blood vessels, abnormal endothelial function can affect blood flow leading to cardiovascular problems, affect athletic performance and even sexual function in men. A meta-analysis of 18 randomized controlled studies found that acute (2h post-ingestion) and chronic (≤18 months) consumption of flavan-3-ol-rich cocoa beverages and chocolate bars significantly increased brachial flow-mediated dilation (FMD), a surrogate marker of endothelial function in participants . A small 15-day, cross-over intervention study in hypertensive individuals with endothelial dysfunction found that 100 g/day of flavan-3-ol-rich dark chocolate, but not 90 g/day of flavan-3-ol-free white chocolate, could restore FMD values almost to normal levels .
The beneficial effect of cocoa on the endothelium may explain why there is data showing cocoa could aid post-workout recovery 
The list of benefits do not end here….There is also some preliminary research indicating that flavonoids may bring health benefits for type 2 diabetes, cognitive function, and some inconclusive data so far on cancer prevention.
A lot more research is needed before we can draw conclusions and translate these findings to clinical applications, but before then, you will find me indulging in some dark, high-quality, fair trade chocolate on the regular and sipping hot cocoa because it is delicious AND may have promising health potential.
Disclaimer: The information contained in this article is my opinion, intended for education only and not to be used as medical advice. The information is accurate to the best of my knowledge up to 4/5/2020, however, as medical research evolves, new information may come to light. The statements have not been evaluated by the FDA. Please always check with your medical provider before implementing any change, and never alter your medical plans or treatments without consulting with your physician first.
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Resources for comparing flavanoid values:
https://www.ars.usda.gov/ARSUserFiles/80400525/Data/Flav/Flav_R03.pdf Food flavanoid values
Dr Chen is a UK medical doctor who lives in California, USA (UK board certified in internal medicine and family practice, MBBS, MRCP, MRCGP). She became interested in integrative medicine when herself and her family had health issues that allopathic medicine could not treat. She decided to get educated on using food as medicine, and became certified as an Integrative Health Practitioner, and now work with her clients to get to the root cause of health issues by using lifestyle measures to help them reach their health goals.
IG handle: @plateful.health
FB handle: @platefulhealth