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Prebiotics and probiotics, microbiome and immune system

Covid-19 deserves the credit for bringing to public attention the crucial role of the microbiome, as a modulator of the immune system. Some ideas on prebiotics and probiotics.

Microbiome, nature and functions

The microbiome it is composed of billions of microorganisms of different species (bacteria, viruses, fungi, protozoa), transmitted by matriarchal, which are found in the intestine and live in symbiosis with our organism, actually performing a function of 'intermediaries' between the external and internal environment. The billions of bacteria belong to over 800 different species, mostly defined as 'commensals' or 'good bacteria' (lactobacilli and bifidobacteria in particular). These, as a whole, constitute the bacterial flora interacting not only with each other, but also with other microorganisms (fungi, archaea, etc.) and with the host.

The bio-functional activities of the microbiome are numerous:

- immunity. Influence of the activity and expression of agents involved in the immune response (cytokines, lymphocytes, dendritic cells, pro / anti-inflammatory agents, etc.),

- digestion. Modulation of the metabolism of some nutrients, production of some neurotransmitters (serotonin etc.), reduction of the possibility of developing allergies and / or intolerances,

- metabolism. The substantial amount of vitamins and important short-chain fatty acids (Short-Chain Fatty Acids, SCFA, eg. butyric and propionic acid), which develops thanks to the fibers included in the diet, intervenes on energy homeostasis. Namely on the modulation of body weight, the disorders associated with obesity and overweight, the suppression of inflammatory signals,

- bidirectional modulation of the gut-brain axis. Gut health affects neurotransmission and mental well-being. A gastrointestinal discomfort, on the other hand, sends signals that in the brain can translate into states of anxiety, stress or depression,

- health and correct functioning of organs and systems. Respiratory, reproductive, liver, kidney, heart, bone and skin health, etc.

Intestinal dysbiosis, causes and effects

Intestinal dysbiosis it is a state of imbalance of the intestinal microflora, which manifests itself with an alteration in the quantity and variety of bacteria present there. Its first causes are identified in:

- unbalanced diets, due to the consumption of junk food or of nutritional deficiencies,

- drugs (e.g. antibiotics, cortisone and anti-inflammatory drugs, laxatives),

- alcohol and smoke,

- contaminants. Agrotoxic residues in food and the environment, endocrine disruptors and toxic substances, also in MOCAs (materials and objects in contact with food) and others everyday objects, fine particles in the atmosphere.

The effects dysbiosis are the increase in intestinal permeability, the weakening of the immune system and thus the greater vulnerability of the organism to the risk of infections.

Microbiome in health, the role of prebiotics

The health of the microbiome it depends on a varied and balanced diet, in the context of a healthy lifestyle. The prebiotics contained in some foods also have an important role in promoting the balance of the intestinal flora, or intestinal eubiosis. The ABC:

A) correct diet rich in prebiotics. Polysaccharides ('non-digestible' fructo- and galacto-oligosaccharides, a specific subgroup of MAC (Microbiota-accessible carbohydrates) modify the composition of the intestinal microbiota. By selectively promoting the growth of Bifidobacterium e Lactobacillus.

MACs are found in fruits, vegetables, whole grains and legumes, the key foods of the Mediterranean diet, in line with the model of 'Healthy diets from sustainable food systems'proposed by the EAT Commission of The Lancet. (1)

Polyunsaturated fatty acids - such as linolenic acid, phytocompounds and phenolic compounds - are also correlated with the balance of the intestinal microbiota and qualified as prebiotics. They are found mostly in vegetables, fruit, fish and nuts.

Clinical Studies Experiments show how the transient alterations of the microbiome induced by the diet are detectable in humans as early as 24-48 hours after the dietary intervention.

B) Physical activity and rest adequate. The recent ones are referred to in this regard WHO guidelines (World Health Organization) is ISS (National Institute of Health).

C) Possible integration of probiotics. These live microorganisms, when administered in adequate quantities and times (> 1 billion per day, for a treatment that can vary from 3-4 weeks to 3 months), can actually exercise beneficial functions for the body.


Probiotics are defined in the FAO / WHO guidelines (2001) as'live microorganisms which when administered in adequate amounts confer a health benefit on the host'(2,3).

The Ministry of Health in the guidelines on probiotics and prebiotics (2018) prescribes that microorganisms used in food and dietary supplements meet the following requirements:

A) tradition of use for the integration of human intestinal microflora (microbiota),

B) food safety. A useful reference is offered by the criteria defined by EFSA on the status by QPS (Qualified Presumption of Safety). In any case, the microorganisms used for food production must not be carriers of acquired and / or transmissible antibiotic resistance,

C) be active and vital when they reach the intestine in such quantities as to multiply there and exert a balancing action on the intestinal microflora by direct colonization (4,5).

Probiotics they are therefore found in some food supplements and fermented foods that belong to the traditional cultures of different peoples. Where fermentation has been used since time immemorial as a method of preserving food. Some examples are the kefir caucasian (fermented milk), the kimchi Korean (fermented cabbage with garlic, ginger, chilli, the miso Japanese (soy fermented with sea salt).

This approach on probiotic products is constantly evolving. Currently, the mechanisms by which specific strains intervene on the prevention and possibly the treatment of some pathologies are not yet clear (6,7,8,9). Finally, there are some scientific studies that show:

- anti-inflammatory effect of a formulation with L. rhamnosus, B. lactis e B. longitude, (10)

- reduction of symptoms and severity of IBS (Irritable bowel syndrome, irritable bowel syndrome), by administering Bifidobacterium Longum BB536Lactobacillus rhamnosus HN001. Thanks to the restoration of intestinal permeability and microbiota balance in patients with IBS, (11)

Symbiotic products

Symbiotic products are foods or dietary supplements consisting of the association of prebiotics and probiotics.

Scientific evidence suggest the effectiveness of prebiotics - thanks to a varied and balanced diet - and probiotics in improving our overall health. With a beneficial action on gastrointestinal pathologies, but also on the strengthening of the immune defenses. Thanks to the contributions to the structure and function of the intestinal barrier, as well as to the well-being of the intestinal microenvironment.

doses, route of administration, inter-individual variability, strain-specific properties are just some of the variables to be investigated before considering the results obtained from certain and reproducible studies.

Dario Dongo and Carlotta Suardi 


(1) The Lancet Commissions. (2019). Food in the Anthropocene: the EAT – Lancet Commission on healthy diets from sustainable food systems. The Lancet, Volume 393, Issue 10170, 2–8 February 2019, Pages 447-492 http://dx.doi.org/10.1016/S0140-6736(18)31788-4

(2) FAO, WHO. Joint FAO / WHO Working Group Report on Drafting Guidelines for the Evaluation of Probiotics in Food. London, Ontario, Canada. April 30 and May 1, 2002, https://www.who.int/foodsafety/fs_management/en/probiotic_guidelines.pdf 

(3) Lorenzo Morelli, Lucio Capurso. (2012). FAO / WHO Guidelines on Probiotics: 10 Years Later. Journal of Clinical Gastroenterology: October 2012 - Volume 46 - Issue - p S1-S2 doi: 10.1097 / MCG.0b013e318269fdd5

(4) Ministry of Health. (2018) Guidelines on probiotics and prebioticshttp://www.salute.gov.it/imgs/C_17_pubblicazioni_1016_allegato.pdf

(5) Dario Dongo (2018). Probiotics and prebiotics, green light from the Ministry. GIFT (Great Italian Food Trade). 15.5.18/XNUMX/XNUMX, https://www.greatitalianfoodtrade.it/salute/probiotici-e-prebiotici-via-libera-del-ministero

(6) Christopher L. Gentile, Tiffany L. Weir. (2018). The gut microbiota at the intersection of diet and human health. Science 362, 776–780 doi: 10.1126 / science.aau5812

(7) Niels Banhos Danneskiold-Samsøea, Helena Dias de Freitas Queiroz Barrosb, Rosangela Santosc, Juliano Lemos Bicasc, Cinthia Baú, Betim Cazarinb, Lise Madsena, Kirsten Kristiansena, Glaucia Maria Pastorec, Susanne Brixf, Mário Roberto Maróstica 2019 Júniorb. Interplay between food and gut microbiota in health and disease. Food Research International 115 23–31. https://doi.org/10.1016/j.foodres.2018.07.043

(8) Maria Gloria Dominguez-Bello, Filipa Godoy-Vitorino, Rob Knight, Martin J Blaser. (2019). Role of the microbiome in human development. BMJ Gut; 0: 1–7. doi: 10.1136 / gutjnl-2018-317503

(9) Paola Palestini, Dario Dongo. (2019). Microbiome and intestine, the second brain. GIFT (Great Italian Food Trade). 14.2.19/XNUMX/XNUMX, https://www.greatitalianfoodtrade.it/salute/microbioma-e-intestino-il-secondo-cervello

(10) Marzia Sichetti, Stefania De Marco, Rita Pagiotti, Giovanna Traina, Donatella Pietrella (2018). Anti-inflammatory effect of multistrain probiotic formulation (L. rhamnosus, B. lactis and B. longum). Nutrition 53 (2018) 95-102. doi I: 10.1016 / j.nut.2018.02.005

(11) Bonfrate L, Di Palo DM, Celano G, Albert A, Vitellio P, De Angelis M, Gobbetti M, Portincasa P. (2020). Effects of Bifidobacterium longum BB536 and Lactobacillus rhamnosus HN001 in IBS patients. Eur J Clin Invest. 2020 Mar; 50 (3): e13201. doi: 10.1111 / eci.13201

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Dario Dongo, lawyer and journalist, PhD in international food law, founder of WIISE (FARE - GIFT - Food Times) and Égalité.

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Nutritionist biologist, ADA II level master at the University of Milan Bicocca. External lecturer at LUNEX University, Luxembourg.

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