Food & Function Blog

In their recent Food & Function review, Manuel Coimbra and co-workers from Aveiro, Portugal, provide a critical overview of the potential health impact of coffee melanoidins. When coffee beans are roasted, the coffee components undergo structural changes leading to the formation of melanoidins (high molecular weight, nitrogenous, brown-coloured compounds), which are linked to antioxidant, antimicrobial, anticariogenic, anti-inflammatory, antihypertensive, and antiglycative behaviour. Their health implications are therefore of great interest.

In order to understand the potential benefits of coffee melanoidins, it is important to know their chemical structures. Studies show that polysaccharides, proteins, and chlorogenic acids are all involved in coffee melanoidin formation; however, their exact structures and formation mechansims are yet to be fully understood.

In this paper the authors provide a critical overview of the knowledge obtained so far about the structure of coffee melanoidins, their mechanisms of formation and their potential health benefits. They also highlight that there are still several unanswered questions and further studies are required to understand the relationship between the chemical structure of the different melanoidins and their biological activities.

To read the Food & Function review in full, please click the link below: free until June 14th!

Coffee melanoidins: structures, mechanisms of formation and potential health impacts, Ana S. P. Moreira, Fernando M. Nunes, M. Rosario Domingues and Manuel A. Coimbra, Food Funct., 2012, DOI: 10.1039/c2fo30048f

You may also be interested in this recently published review on ‘Effects of tea and coffee on cardiovascular disease risk‘ from Food & Function Editorial Board member Kevin Croft.  Or, if you are interested in keeping up to date with the latest articles published in Food & Function why not sign up for free table of contents alerts.

In this Food & Function review article, Adrian Cookson and co-workers from New Zealand look at how the mucus layer covering the gastrointestinal tract is influenced by intestinal bacteria and dietary components.

The large bowel provides the ideal environment for the growth of many genera of bacteria, in particular, bifidobacteria and lactobacilli. The complex bacterial community can be altered by introducing fermentable dietary components such as starch, non-starch polysaccharides, and non-digestible oligosaccharides, selectively stimulating the growth of specific strains of bifidobacteria. These dietary components can change the metabolic end products of bacterial fermentation, which in turn are able to modify the expression of mucin genes and proteins leading to an increase in the mucus layer thickness. However, the relationship between dietary components, the adherent bacterial community and host function remains to be fully understood.

The review also discusses the effects of dietary components on the microbial community, through the selective growth stimulation of specific bacterial species, and how this may alter the end-products of bacterial fermentation and ultimately affect the mucus layer.

Read the full article for free until 29th May by clicking the link below.

The interactions between endogenous bacteria, dietary components and the mucus layer of the large bowel, Alicia M. Barnett, Nicole C. Roy, Warren C. McNabb and Adrian L. Cookson, Food Funct., 2012, DOI: 10.1039/c2fo30017f

You may also be interested in… Nuclear translocation of NF-κB in intact human gut tissue upon stimulation with coffee and roasting products, Tanja Sauer, Martin Raithel, Jürgen Kressel, Sonja Muscat, Gerald Münch and Monika Pischetsrieder, Food Funct., 2011,2, 529-540 DOI: 10.1039/C1FO10055F, Paper

You can keep up to date with the latest developments from Food & Function by signing up for free table of contents alerts and monthly e-newsletters.

Carbohydrates such as sugars, starches and fibers are an important part of a healthy diet. However, government and health organizations around the world have differing guidelines for the intake and type of sugars, which are often generalised and vague. This can cause confusion for nutrition practitioners, especially in relation to “added sugar”. Consuming excess calories ultimately leads to weight gain as the calories are turned into fat by the body, therefore guidelines to asssit nutritionists may help control obesity and its related conditions.

Scientists from the US have now reviewed the health concerns about dietary sugars, and have compiled dietary guidelines for sugars issued by various organizations. In their review, Joanne Slavin and co-workers point out a need for consistent terminology and definitions in order to provide better guidance. They also note that nutrition professionals are often needed to guide the dietary choices of individuals and families, not large populations. Therefore it is important that practitioners consider factors such as health status, habits, calorific needs, and lifestyle in order to effectively translate population-based sugar guidance statements to individuals.

Click the link below to read the full review. It’s free to access for 6 weeks until the 6th May:

The confusing world of dietary sugars: definitions, intakes, food sources and international dietary recommendations, Jennifer Hess, Marie E. Latulippe, Keith Ayoob and Joanne Slavin, Food Funct., 2012, DOI: 10.1039/c2fo10250a

You can keep up to date with the latest developments from Food & Function by signing up for free table of contents alerts and monthly e-newsletters.

Scientists in the US have investigated the effects of quercetin (a flavonoid found in many vegetables) on the uptake of green tea polyphenols. Green tea polyphenols (GTPs) have previously been shown to display anticarcinogenic activity against lung, liver and pancreatic cancer; however, their concentration in human plasma is quite low and ways to increase their bioavailabilty is therefore of great interest. 

The research team found that that quercetin increased the bioavailability of GTPs and decreased their methylation leading to an enhanced antiproliferative effect in different cancer cells in vitro and in vivo. Quercetin increased the cellular absorption of epigallocatechin gallate (an active component of green tea) four-fold. The results suggest that eating foods rich in quercetin, such as onions, apples and red wine may help prevent cancer.

This article is free to access for 4 weeks!  Click on the link below to read the article in full:

Quercetin increased bioavailability and decreased methylation of green tea polyphenols in vitro and in vivo, P. Wang, D. Heber and S. M. Henning, Food Funct., 2012, DOI: 10.1039/c2fo10254d

You can keep up to date with the latest developments from Food & Function by signing up for free table of contents alerts and monthly e-newsletters.

Scientists from Portugal have studied how anthocyanins are absorbed in the stomach using an in vitro model. Anthocyanins are flavonoid compounds which can be found in blueberries, raspberries and blackcurrants, but their bioavailability is difficult to assess because they exist as different structures in equilibrium depending on pH.

The stomach is often ignored as a metabolizing organ although it has been identified as a site of absorption for different compounds. In this work, adenocarcinoma stomach cells (MKN-28) as a model of the gastric barrier was used to investigate the absorption and metabolism of anthocyanins. The results show that anthocyanins can cross MKN-28 cells in a time dependent manner via a saturable transport mechanism. Also the succesful use of the MKN-28 cell line as a model for gastric digestion could be implemented for other screening procedures and in turn give new insight on bioavailability.

Click the link below to read the article in full. Free to access until April 10th:

A new approach on the gastric absorption of anthocyanins
Iva Fernandes, Victor de Freitas, Celso Reis and Nuno Mateus
Food Funct., 2012, DOI: 10.1039/c2fo10295a

You may also be interested in the article below which is also free to access:

Development of a simple model device for in vitro gastric digestion investigation
Jianshe Chen, Vishwajeet Gaikwad, Melvin Holmes, Brent Murray, Malcolm Povey, Ye Wang and Ying Zhang
Food Funct., 2011, 2, 174-182, DOI: 10.1039/C0FO00159G

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Researchers from France have described a new method of combining an in vitro digestion method with a Caco 2 cell model to study lipid digestion, absorption and conversion to lipid bodies and used this to study the influence of the structure of dietary lipid sources during digestion.

Until recently, studies on dietary fats only considered the impact of their global intake and their total fatty acid composition, not  their structure in foods. By understanding the intake and absorption of dietary oils, diseases such as obesity, diabetes and atherosclerosis (which are characterised by a high fat diet) can be better understood.

In this work, four emulsions based on  milk fat olein (OL) or rapeseed oil (RA) as the dispersed phase and either lecithin or sodium caseinate as the emulsifier were examined. It was demonstrated that in vitro digestion fluids resulting from food emulsions could be used to incubate on Caco-2 cells as a new model for testing emulsion digestion and absorption. It was also shown that the emulsion composition influenced the activation of lipid metabolism and TAG secretion.

To read the full article, click the link below. Read it for free until 23rd March.

Coupling in vitro gastrointestinal lipolysis and Caco-2 cell cultures for testing the absorption of different food emulsions, Cecile Vors, Perrine Capolino, Clemence Guerin, Emmanuelle Meugnier, Sandra Pesenti, Marie-Agnes Chauvin, Julien Monteil, Noel Peretti, Maud Cansell, Frederic Carriere and Marie-Caroline Michalski, Food Funct., 2012, DOI: 10.1039/c2fo10248j

You may also be interested in this review article which is free to access

Review of in vitro digestion models for rapid screening of emulsion-based systems
David Julian McClements and Yan Li
Food Funct., 2010, 1, 32-59, DOI: 10.1039/C0FO00111B

You can keep up to date with the latest developments from Food & Function by signing up for free table of contents alerts and monthly e-newsletters.

Scientists in Australia and China have investigated the effects of dietary nitrate intake on nitric oxide (NO) status. NO is important for the control of vasodilation and blood pressure and it can be obtained from the arginine/NOS pathway in cells, but also via nitrates in foods such as spinach and cabbage.

The mechanism of nitrate intake in the mouth is important because about 25% of dietary nitrate is secreted into saliva, of which approximately 20% (5% of the ingested intake) is converted to nitrite in the mouth by bacteria on the tongue. The nitrite is swallowed and is converted to NO in the acidic environment of the stomach or is absorbed and further reduced to NO in the body through a number of mechanisms. This pathway can be interrupted by spitting and not swallowing the nitrite-rich saliva or by the use of antibacterial mouth wash; it is unknown whether the use of antibacterial toothpaste interrupts the pathway.

In this study, the dose–response of dietary nitrate on both NO status and nitrate reduction in the mouth was assessed. It was found that increasing nitrate intake results in a linear dose-related increase in nitric oxide status and nitrate reduction in the mouth. It was also found that the use of antibacterial toothpaste does not inhibit nitrate reduction.

To read the article in full, click the link below: it’s free to access until 20th March.

Nitrate causes a dose-dependent augmentation of nitric oxide status in healthy women, Catherine P. Bondonno, Kevin D. Croft, Ian B. Puddey, Michael J. Considine, Xingbin Yang, Natalie C. Ward and Jonathan M. Hodgson, Food Funct., 2012, DOI: 10.1039/c2fo10206d

You may also be interested in this article which is also free to access:

Dealcoholized red wine reverse vascular remodeling in an experimental model of metabolic syndrome: role of NAD(P)H oxidase and eNOS activity
Marcela Alejandra Vazquez-Prieto ,  Nicolás Federico Renna ,  Carina Lembo ,  Emiliano Raúl Diez and Roberto Miguel Miatello, Food Funct., 2010, 1, 124-129, DOI: 10.1039/C0FO00077A

You can keep up to date with the latest developments from Food & Function by signing up for free table of contents alerts and monthly e-newsletters.

Ana Martinez and colleagues from Mexico have reported a theoretical study on the antioxidant mechanism of xanthones. Xanthones are bioactive compounds found in tropical fruits such as mangosteen (Garcinia mangostana) and have shown antioxidant behaviour in a number of experimental studies, however the mechanism of action is not thoroughly understood.

In this work, the antioxidant properties of 20 xanthones and 8 xanthone anions were studied and the more efficient free radical scavengers were identified using a theoretical approach based on single electron transfer (SET). The quantum chemical calculations showed that the reaction between xanthones and OH radicals is thermodynamically unfavourable, however the reaction between xanthone anions (which are present under physiological conditions) and OH radicals is exergonic, and so xanthone anions behave as antioxidants by deactivating the OH free radical species. Understanding the free-radical scavenging mechanisms of these compounds may help combat degenerative diseases such as Alzheimer’s disease which are linked to the antioxidant mechanistic pathway.

Read the article in full by clicking the link below. It’s free to access until March 13th!

Xanthones as antioxidants: a theoretical study on the thermodynamics and kinetics of the single electron transfer mechanism, A. Martínez, E. Hernández-Marin and A. Galano, Food Funct., 2012, DOI: 10.1039/C2FO10229C

 You may also be interested in the following article which is free to acces.

Dietary chromones as antioxidant agents—the structural variable, M. M. Dias,  N. F. L. Machado and M. P. M. Marques, Food Funct., 2011, 2, 595-602, DOI: 10.1039/C1FO10098J

You can keep up to date with the latest developments from Food & Function by signing up for free table of contents alerts and monthly e-newsletters.

Scientists from Massey University, New Zealand, have investigated the physicochemical and microstructural changes of sodium caseinate-stabilized emulsions during lipid digestion in simulated gastric fluid (SGF) containing pepsin.

During passage through the gastrointestinal tract a food product passes through many different and complex environments from the mouth to the stomach and then to the intestine.  During this journey food will be exposed to widely different pHs, enzymes electrolytes and mechanical environments.  Model systems are thus used to understand such complex conditions because they allow the digestion behaviour and the interactions of individual physiological components of an emulsion to be investigated separately.

The milk protein casein is known to be easily hydrolysed because of its relatively open flexible structure and during digestion it may be hydrolysed by pepsin, which in turn may lead to changes under gastric conditions in the physicochemical properties of the emulsions. The emulsions can also undergo further change when they enter the small intestine.

In this study, the average size, size distribution, microstructure, proteolysis of interfacial proteins and lipolysis of the emulsion droplets were monitored as a function of digestion time. It was found that digestion in SGF accelerated the coalescence of emulsion droplets during simulated intestinal digestion. However, the changes in the size and the microstructure of the emulsions under gastric conditions did not appear to influence the rate and the extent of lipid digestion in the subsequent intestinal environment.

To read the full article, click the link below.  Free until 15th February:

Influence of gastric digestive reaction on subsequent in vitrointestinal digestion of sodium caseinate-stabilized emulsions, Jessie Li, Aiqian Ye, Sung Je Lee and Harjinder Singh, Food Funct., 2012, DOI: 10.1039/c2fo10242k

Also of interest and free to access:

Review of in vitro digestion models for rapid screening of emulsion-based systems
David Julian McClements and Yan Li, Food Funct., 2010, 1, 32-59, DOI: 10.1039/C0FO00111B

Scientists from Canada have investigated b-carotene release from lipid nanodispersions under simulated gastrointestinal conditions. Enhancing the health benefits of food by incorporating bioactive molecules (such as b-carotene) is of increasing interest as it may help with chronic conditions. The bioactives can be incorporated into the food matrices by designing oil-in-water emulsions.

In this work, the influence of interfacial structure of solid lipid nanoparticle dispersions and oil-in-water emulsions containing encapsulated b-carotene  were examined under simulated gastrointestinal conditions. It was found that the uptake of lipolytic products and lipophilic bioactives depended on nonionic surfactant type, the extent of lipid digestion, as well as the presence of bile salts and phospholipids.

This work was presented at the Delivery of Functionality in Complex Food Systems Symposium held in Guelph in August 2011, and is part of our themed issue on the Delivery of Functionality coming soon in 2012. The article is free to access until the end of 2011, to read it in full click the link below:

Digestibility and b-carotene release from lipid nanodispersions depend on dispersed phase crystallinity and interfacial properties, Amir Malaki Nik, Sarah Langmaid and Amanda J. Wright, Food Funct., 2012, DOI: 10.1039/c1fo10201j