“Death sits in the bowels”. “Bad digestion is the root of all evil”.-Hippocrates 400 B.C. It appears that this statement was ignored for a long time. I will first rely on information from a paper by Duda-Chodak et al, titled “Interaction of dietary compounds, especially polyphenols,with the intestinal microbiota: a review” published in the European Journal of Nutrition (2015) 54:325–341. I must add that it is my continuing search on cocoa health benefits, which leads me to new frontiers. The authors noted that for many years, it was thought that the function of the largeintestine was to reabsorb water and salt and remove unusedfood debris. It was now clear that the intestinal microbiota(gut flora) played a crucial role in the metabolism ofchemical compounds found within foods. The large numberof bacteria inhabiting the large intestine formed a highlycomplex ecosystem-intestinal microbiome.
In 2007, the‘human microbiome project’ was launched with the aim ofcollecting and integrating genomic information from manydiverse human microbiomes and examining the relationshipbetween changes in the human microbiome and variousdiseases. This led to several similar projects across the globe, the NIH Human Microbiome Project (2007, USA), the Irish ELDERMETProject (2007–2013), the European project-Metagenomics of the human intestinal tract (MetaHIT 2008–2011), the French project Microbes (human
intestinal microbiome in obesity and nutritional transition,2008–2010), the Australian jumpstarthuman microbiome project (2009), the Canadian HumanMicrobiome Initiative (2009) and theKorean Microbiome Diversity Project (2010–2015). All these references are to let you know, dear reader, how far research has gone to unearth the previously unknown linkage between the functions of the gut flora and human health.
The human gut was colonized by an enormous number ofmicroorganisms, mainly bacteria, about ~1014 bacterialcells, that is ten times more than the total number ofhuman cells. The metabolic capacity of the intestinalmicrobiome was approximately 100-fold greater than thatof the human liver.
The process of gut colonization started immediately afterbirth. The infant’s microbiota with initialinstability andlow diversity, evolved into a more stable adult-type microbiota
after the first 2–4 years of life. Its final compositiondepended on environmental factors.
Breastfeeding was a significant factor in thedetermination of the neonatal gut microbiota. In full-timebreastfed babies (1 month old), bifidobacteria constituteda predominant group in the faeces, while in formula-fedinfants, although bifidobacteria were also the predominantspecies, other bacteria such as enterobacteria, enterococci,lactobacilli, clostridia and Bacteroides spp. were presentin significantly higher numbers compared with breastfedinfants. Although host geneticscould predict microbial composition, severalextrinsic factors (mode of infant delivery, antibiotic exposure, neonatal nutrition, adult nutrition, stress, age, degreeof hygiene, bacterial infections) contributed to the developmentof an individual’s unique microbial composition and susceptibility to several diseases. It hasbeen shown that infants born vaginally acquire their ownmother’s vaginal and intestinal flora (dominated by Lactobacillus,Prevotella, Atopobium or Sneathia spp.) and havehigher levels of Clostridium spp, while infants delivered bycesarean section have increased levels of skin-associatedbacteria including Staphylococcus, Corynebacterium andPropionibacterium spp.
The microbiota of the human gastrointestinal tract startedin the mouth, with the number of viable cells estimated at108–1010 colony-forming units (CFU) of bacteria per gramof saliva. As a result of the swallowing reflex, these bacteriawere continuously transferred to the subsequent parts ofthe gastrointestinal tract. The number of microorganisms wassignificantly reduced in the stomach (~103 CFU/g gastricjuice), duodenum and jejunum (102–104 CFU/g content). This increased in the ileum and colon (about 1010 CFU/g content and 1010–1012 CFU/g content, respectively).
The composition of the humangut ecosystem was influenced by multiple and diverse factors,
such as age, origin, environment, dietary habits (includingprobiotics) and the application of antibiotics. Hence, eachindividual had his or her own unique profile of microbialspecies just like a fingerprint. In spite of diversity of bacterial species, the majority (98 % of
all species) belonged to only four bacterial phyla: Firmicutes(64 %), Bacteroidetes(23 %), Proteobacteria(8 %) andActinobacteria(3 %), whereas other minor taxonomic divisions
were quite diverse. It should be emphasizedthat the ratio between these groups was strongly dependenton the location within the intestine, and on the ethnicityof the host. Firmicutesand Bacteroidetesdominated in thelarge intestine, while in the jejunum Proteobacteriaweremore abundant than Bacteroidetes.
The ratio of Firmicutes over Bacteroidetes (F/B) changed throughout the lifespan. The ratio was lower in thefirst year of life (0.4), increased in adulthood (10.9), anddecreased during old age (0.6). The ratio of Firmicutesto Bacteroideteswas higher in obese than in lean humans. This ratiodecreased with weight loss on a low-calorie diet. This means that in addition to the effect of excesscalories per se, a high-calorie diet predisposed to obesitythrough microbiota modulation, which manifested by theincreased F/B ratio. Therefore, the F/B ratio served asa useful biomarker of obesity.
A balance between the host immune system and the commensalgut microbiota was crucial for maintaining health.If this balance was disturbed (dysbiosis), the host–microberelationship could progress toward disease. Dysbiosiscan be diet-related. Microbespresent in the human gut were essential for the process ofdigestion in the host. Microbes were also essential in the synthesesof vitamins and amino acids. In contrast, some compoundspresent in the diet caould modulate the microbiotacomposition and result in in changes in the metabolic activityof intestinal bacteria.
The composition of the gut microbiota was susceptible tothe quality and quantity of ingested carbohydrates-the main carbon and energy source for the microbes. Any imbalance could result in the over-growth of opportunistic pathogensand weaken the host defense against infection andchronic inflammation, through alterations in mucosalimmunity.
Dietary interventions designed to promote short chain fatty acids (SCFA) production in the colonhave proven beneficial in the treatment ofdysbiosis.Flavonols, apart from promoting the growth of beneficial microbes, modulated the gut microbiota byaffecting the adhesion of bacteria to intestinal cells. Thus, a diet in polyphenols have proven beneficial in reducing gastric inflammationor stomach cancer induced by Helicobacter pylori (H. pylori). In a related study, anthocyanins (a polyphenol found in some foods, e.g. cocoa) sigificantly enhanced the growth of Bifidobacteriumspp. and Lactobacillus–Enterococcus spp- showing thatanthocyanins and their metabolites exerted a positiveeffect on the intestinal bacterial population.
Another paper showing the positive effects of polyphenols on gut flora was by Rasnik et al, titled “Influence of diet on the gut microbiomeand implications for human health” published in the Journal of Translational Medicine (2017) 15:73. This examined the effects dietary polyphenols from common foods/fruits (seeds, vegetables,tea, cocoa products, and wine. )
Commonlyenriched bacterial genera amongst studies analyzingthese food sources included Bifidobacterium and Lactobacillus. Recorded health benefits included immune-modulation, anti-cancer, anti-bacterial and anti-inflammatory effects.Furthermore, consumption of cocoaderivedpolyphenols led to significantincreases in plasmahigh-density lipoprotein (HDL)-cholesterol and significant reductions inplasma triglyrides and C-reactive protein concentrations. C-reactive protein is a biomarker for inflammation and diseases.
It is clear that our gutmicrobiome has a profound impact on our health. The health effects are positively modulated by diets high in polyphenols. Cocoa is the richest food source of polyphenols on weigh basis. Increased comsumption would improve gut health and improve the health and wellbeing of individual.
DR. EDWARD O. AMPORFUL