Yoghurt and lactose: cooperation for nutrition

Lorenzo MorelliIstituto Microbiologia UCSC

Piacenza – Cremona Italylorenzo.morelli@unicatt.it

Yoghurt and lactose: «characters of this opera»

1. Lactose2. Lactose maldigesters

3. Yogurt4. Yogurt bacteria

Main characters of this presentation:

The sugar of «mammals» At its appearance it was unknown to bacteria (evolutionary more «ancient» than mammals) Most bacteria «still» unable to ferment lactose Some bacteria have solved this evolutionary problem

1.Lactosemammalian milk is the only known natural source of significant amounts of lactose

Lactose: a young actor or an actor for the youngs?

As this is the sugar of mammals it plays some positive roles for infant nutrition:

- Lactose constitutes around 40% of the energy provided by breast milk

- It has been also suggested that it increases mineral absorption

- It has been also suggested that lactose could have a prebiotic effect

Grenov et al, 2016

Lactose: a young actor or an actor for the youngs?Bifidobacteria are key players for the health of infants…

Some bifidobacteria utilize lactose better that glucose…

Amaretti et al, 2006

Lactose digestion in adults

Vonk et al,2012

Main characters of this presentation:

2. Lactose maldigesters3. Biological Mechanism of Lactose Intolerance

About two thirds of the World’s population undergoes a genetically programmed decrease in lactase synthesis after weaning (primary lactase deficiency) . Additionally, in individuals with lactase persistence the occurrence of gastrointestinal infection, inflammatory bowel disease, abdominal surgery and other health issues can also cause a decrease in lactase activity (secondary lactase deficiency.Whatever the cause, lactase deficiency results in unabsorbed lactose being present in the intestinal tract, which has effects that can lead to symptoms of lactose intolerance in susceptible individuals .

Deng et al, 2015

2. Lactose maldigesters: just to define

LACTASE DEFICIENCY AND LACTOSE INTOLERANCE:

... Lactose tolerance varies widely among individuals with lactose maldigestion.

A single threshold of lactose for all lactose intolerant subjects cannot be determined owing to the great variation in individual tolerances.

…The vast majority of subjects with lactose maldigestion will tolerate up to 12 g of lactose as a single dose with no or minor symptoms.

Higher doses may be tolerated if distributed throughout the day.

2. Definitions: just to summarize

Szilagy,2015

Vonk et al,2012

What happens with undigested lactose ?

2. Lactose intolerance3. Biological Mechanism of Lactose Intolerance

About 2/3 of the World’s population undergoes a genetically programmed decrease in lactase synthesis after weaning (primary lactase deficiency) .

Additionally, in individuals with lactase persistence the occurrence of gastrointestinal infection, inflammatory bowel disease, abdominal surgery and other health issues can also cause a decrease in lactase activity (secondary lactase deficiency).

Whatever the cause, lactase deficiency results in unabsorbed lactose being present in the intestinal tract, which has effects that can lead to symptoms of lactose intolerance in susceptible individuals .

Deng et al, 2015

Long-term effects of lactose restriction

Although restricting dietary lactose or FODMAPs (fermentable oligo-, di-, monosaccharides and polyols) may improve gastrointestinal complaints, long-term effects of a diet free of dairy or FODMAPs products may be of concern => Dairy products are the major source of calcium in many individuals. No study has addressed the safety and effectiveness of calcium replacement for patients with lactose intolerance; …

Diet also has effects on the colonic microbiome. Altering the dietary intake of FODMAPs alter gastrointestinal microbiota and a significant decrease in the concentration of probiotic bifidobacteria after four weeks of a low FODMAP diet has been reported . Whether this change has any long-term implications is unknown.

Deng et al, 2015

Main characters of this presentation:

3.YOGURT

Main characters of this presentation:

4.YOGURT BACTERIA

Streptococcus thermophilus

Lactobacillus delbrueckii subsp bulgaricus

The plot: how bacteria have solved this evolutionary drama

Uptake viaATP permease

Uptake viaPEP PTS It requires metabolically active bacterial cells

The plot: how bacteria have solved this evolutionary drama

Only the Leloir pathway is active in unviable, lysed bacterial cells

Yogurt bacteria use the Leloir pathway

Also on stage • Yogurt is characterised by the presence,

when consumed, by an high bacterial count.

• Streptococci and Lactobacilli are then viable at the moment of the ingestion

• And afterwards?

Costumes: yogurt bacteria must wear «viability»

Savaiano, 2014

Scenario : Low survival to intestinal transit

but HIGH lactase activity

Scenario : the viability of yogurt cultures make the difference !

Savaiano et al, 1984

Hydrolysis of lactose by unviable bacteria also in ripened cheeses

«ITEMS»Istituto Danone, 1998

A first conclusionIt is then possible to assume that lactose hydrolysis is deeply

related to the evolutionary history of mammals and bacteria .

Some bacteria inhabiting the human intestine and relevant for our

health are potent lactose fermenters, in a «prebiotic» way

Yogurt bacteria (as well as some other lactic acid bacteria) are able to

hydrolyze lactose even if unviable (but they have to be viable at

the moment of ingestion) thanks to their specific uptake system.

A regulatory view.In the European Union the use of health claims made on food is strictly regulated (Reg EC1924/2006)

Very few claims approved after the assessment of the available data by the European Food Safety Authority

BUT

The lactose hydrolysing ability of yogurt bacteria has been successufully recognized

A regulatory view.

A regulatory view.

A regulatory view.

A regulatory view.

A regulatory view.

To conclude…we may use the EFSA conclusions

To conclude…we may use the EFSA conclusions

To conclude

THANKS FOR YOUR

ATTENTION