Mai bun ca uleiul de peste

Piata globala a uleiului de peste va atinge 4 miliarde de dolari in 2022. Avand in vedere rolul acizilor grasi omega-3 in reducerea inflamatiilor, tensiunii arteriale si colesterolului rau, alaturi de boli de inima in general, nu este de mirare! 

Exista totusi persoane in industria nutritiei care spun ca in cele din urma uleiul de peste va fi depasit - cel putin in popularitate si vanzari - de un alt suplimente cu o gama larga de beneficii. Ceva numit beta-glucan; este in regula daca nu ai auzit de asa ceva pana acum. Abia si-a scos capul in lumea nutritiei mainstream.

Ce sunt beta-glucanii si ce fac ei? 

Beta-glucanii sunt polizaharide (un carbohidrat cu cateva molecule de zahar legate impreuna) care apar in peretii celulari la anumite cereale, bacterii, ciuperci si alge. 

Interesant este ca dupa ce ii ingeram, sistemul imunitar uman ii vede precum molecule asociate cu patogenii. Asta inseamna ca beta-glucanii activeaza atat imunitatea inascuta cat si dobandita, ceea ce este un lucru bun. 

Imunitatea inascuta este cea cu care te nasti. Este alcatuita din celule specializate prcum neutrofilele, monocitele, celulele ucigase si un set de 30 de proteine sanguine numite proteine complementare. Impreuna organzieaza atacuri impotriva patogenilor invadatori. 

Imunitatea dobandita (adaptativa) include celule care necesita antrenament. Fiecare infectie invata celulele T si celulele B sa produca anticorpi care ataca anumite infectii. Aceste celule "isi amintesc" infectia si produc o imunitate pe termen lung (este si principiul majoritatii vaccinurilor). 

Se credea initial ca beta-glucanii activeaza doar imunitatea inascuta, ceea ce era grozav, dar cercetari recente arata ca activeaza si imunitatea dobandita, ceea ce este si mai grozav.

In practica inseamna ca beta-glucanii au proprietati imunomodulatoare, antimicrobiene, antioxidante si radioprotective (protejeaza tesuturile de radiatii). Si cum beta-glucanii sunt in esenta fibre insolubile, se speculeaza ca pot avea si efecte cardioprotective printr-un mai bun control al colesterolului, greutaii si raspunsului glicemic. 

Sa fim intelesi: beta-glucanii nu unt patogeni! Doar pacalesc sistemul imunitar si il fac sa creada ca este atacat, obtinand un raspuns de la el. Mentin sistemnul imunitar in alerta, astfel acesta avand un raspuns mai rapid si eficient daca ceva chiar il ataca. 

Dovezi stiintifice? 

S-au facut o multime de cercetari asupra beta-glucanilor, si ceva studii umane. Ce se intampla cand pacienti (cu varste intre 25 si 65 de ani) primesc beta-1,3-glucan timp de 90 de zile:

• 2,3 zile in minus de imbolnavire
• 70% mai putine simptome ale infectiei a tractului respirator superior
• 10 zile in minus de astfel de simptome
• 45% mai putine episoade de simptome ale infectiei a tractului respirator superior
• 80% mai mica severitatea simptomelor

Este doar un studiu, dar 17 alte studii au observat ca beta-glucanii cresc rezistenta la infectii ale tractului respirator superior. Alte 8 studii au observat ca sportivi de elita cat si amatori de sport au o scadere mult mai mica a sistemului imunitar dupa exercitii intense.

Alte studii au vazut ca beta-gluanii ajuta la ameliorarea alergiilor, reducerea aparitiei herpesului si chiar pot reduce durerile cauzate de osteoartrita. 

Se pare ca vasta nu este un factor in eficienta lor, functioneaza la fel de bine la tineri cat si la batrani. Si nu s-au observat efecte adverse. 

Pot lua suficient beta-glucan din mancare?

Pe scurt, nu prea! La inceput credeam ca poti lua doze suficiente din mancare, consumand de exemplu ovaz, 50 g pe zi. Asta ar insemna 2-3 grame de beta-glucani. Dar se pare ca lucrurile nu sunt atat de simple. Ovazul, la fel ca alte plante cu continut mare de beta-glucan, are un amestec de diferiti izomeri de beta-glucani. Nu este rau, dar beta-1,3-glucan este mai puternic. 

Mai mult, tractul nostru intestinal nu digera foarte bine peretii celulari ai acestor grane, asa ca nu abosrbim foarte bine beta-glucanul din ele. Si in final, cand beta-glucanul nu este purificat, contine multe impuritati, deseori actionand impotriva efectelor biologice ale moleculei. 

Pentru a obtine la maxim efectele benefice ale beta-glucanului este nevoie de suplimentare cu beta-1,3-glucan.  De regula se extrage din alge precum Euglena gracilis, acestea avand o concentratie de beta-glucan in peretii celulari de 95%. 

Referinte

1. M. Rondanelli, et al. The biological activity of beta-glucans. Minerva Med. 2009 Jun;100(3):237-45. – This review summarizes the recent knowledge about the positive effect of beta glucans on human health. Quote: "A growing body of science indicates that beta-glucans promote health in a number of important ways. For instance, several studies have also shown that oat beta-glucans blunt the glycemic and insulin response. Moreover, beta-1,3-glucans improve the body's immune system defense against foreign invaders by enhancing the ability of macrophages, neutrophils and natural killer cells to respond to and fight a wide range of challenges such as bacteria, viruses, fungi, and parasites."
2. Vetvicka V, Vetvickova I. Glucans and Cancer: Comparison of Commercially Available B-glucans – Part IV. Anticancer Res, 38(3):1327-1333, Mar 2018. – Quote: "Among the well-studied effects of B-glucans, we can mention stimulation of both humoral and cellular immunity, metabolic control of diabetes, stimulation of wound healing, stress reduction, attenuation of chronic fatigue syndrome, lowering cholesterol levels, and inhibition of cancer. ...Chronic respiratory problems. In Japan, glucan has been widely used, for over 30 years, in the treatment of gastrointestinal cancer."
3. Davis, JM, Murphy, EA, Brown AS, Carmichael, MD, Ghaffar A, Mayer EP. Effects of oat beta-glucan on innate immunity and infection after exercise stress. Med Sci Sports Exerc. 2004, Aug;36(8):1321-7. – These data suggest that daily ingestion of beta glucan may offset the increased risk of upper respiratory tract infections (URTI) associated with exercise stress, which may be mediated, at least in part, by an increase in macrophage antiviral resistance.
4. Julia J. Volman, et al. Dietary modulation of immune function by β-glucans. Physiology & Behavior, Volume 94, Issue 2, 23 May 2008, Pages 276-284. – The immune response can be modulated by nutrients like β-glucans, which are glucose polymers that are major structural components of the cell wall of yeast, fungi, and bacteria, but also of cereals like oat and barley. In this review the current status concerning possibilities to modulate immune function by β-glucans is discussed. In vitro as well as in vivo studies in animals and humans show that especially β-glucans derived from fungi and yeast have immune modulating properties. Most frequently evaluated are effects on leukocyte activity, which has been suggested to contribute to the increased resistance against infections observed after β-glucan interventions.
5. Vaclav Vetvicka, Jana Vetvickova, β-Glucan Improves Conditions of Chronic Fatigue in Mice by Stimulation of Immunity. The Open Biochemistry Journal, 2-18-2020. – This study found that glucan supplementation strongly improved the suppressed phagocytosis and changes in cytokine and levels of oxidative stress markers caused by fatigue. In addition, glucan supplementation also increased the motor functioning of tested animals.
6. Dalia Akramiene, et al. Effects of ß-glucans on the immune system. Medicinia, 11 August 2007. – This paper explains how ß-Glucans are naturally occurring polysaccharides. These glucose polymers are constituents of the cell wall of certain pathogenic bacteria and fungi. These substances increase host immune defense by activating the complement system, enhancing macrophages and natural killer cell function. ß-Glucans also show anti-carcinogenic activity. They can prevent oncogenesis due to the protective effect against potent genotoxic carcinogens. As immunostimulating agents, which act through the activation of macrophages and NK cell cytotoxicity, ß-glucan can inhibit tumor growth in promotion stage, too.
7. McFarlin BK, Carpenter KC, Davidson T. Baker's yeast beta glucan supplementation increases salivary IgA [immunoglobulin] and decreases cold/flu symptomatic days after intense exercise. J Diet Suppl 10(3):171-83, Sept 2013. – Beta glucan was associated with a 37% reduction in the number of cold/flu symptom days postmarathon compared to placebo (p = .026).
8. Kwanghook, K., et al. Algae-derived β-glucan enhanced gut health and immune responses of weaned pigs experimentally infected with a pathogenic E. coli. Animal Feed Science and Technology, Volume 248, February 2019 – Quote: "Feed supplementation of algae-derived β-glucan alleviated diarrhea of F18 E. coli infected pigs by enhancing gut integrity. Feeding β-glucan also boosted host immune response against E. coli infection."
9. Borchani C, Fonteyn F, et al. Structural Characterization, Technological Functionality, and Physiological Aspects of Fungal B-D-glucans: A Review. Crit Rev Food Sci Nutr, 56(10:1746-52, PMIC 25830657, Jul 2016 – Quote: "Thus, they [(1-3)(1-6)-B-glucans] are effective in inhibiting growth of cancer cells and metastasis and preventing bacterial infection. In humans, B-glucans reduce blood cholesterol, improve glucose absorption by body cells, and so help wound healing."
10. Graugaum H-J, Busch R, Stier H. A double-blind, randomized, placebo-controlled nutritional study using an insoluble yeast beta-glucan to improve the immune defense system. Dood Nutr Sci, 3(6):738-746, June 2012. – In a placebo-controlled, double-blind, randomized clinical trial, the effect of an insoluble yeast beta-glucan preparation on the incidences of common colds and its effect on common cold symptoms were compared to placebo. ...the beta-glucan group had significantly less infections compared to placebo. Beta-glucan significantly reduced the typical cold symptoms ('sore throat and/or difficulty swallowing', 'hoarseness and/or cough' and 'runny nose') as opposed to placebo. The present study demonstrated a prophylactic [preventative] effect of yeast beta-glucan on the occurrence of common colds as opposed to placebo. In addition, when these episodes occurred, they were from the beginning less pronounced and subsided faster.
11. Carlos A.F. Oliveira, et al. β-Glucan successfully stimulated the immune system in different jawed vertebrate species. Comparative Immunology, Microbiology and Infectious Diseases, Volume 62, February 2019, Pages 1-6. – Several reports have shown the positive effects of β-glucans on the immune system. For 28 days, scientists, fed four different vertebrate species: mice, dogs, piglets and chicks, with two β-glucan molecules (BG01 and BG02). They measured the serum interleukin 2 as an indicator of innate immune response, the neutrophils and monocytes phagocytosis index as a cellular response, and antibody formation as an adaptive response. The results clearly showed that the different β-glucan molecules exhibited biologically differently behaviors, but both molecules stimulate the immune system in a similar pattern in these four species. This finding suggests that vertebrates shared similar mechanisms/patterns in recognizing the β-glucans and confirms the benefits of β-glucans across different vertebrate species.