The global health effects of yogurt are beyond the single effects of each nutrients and live bacteria, as indeed, “yogurt is more than the sum of its parts”. The updated scientific data about food matrix benefits of yogurt will be the topic of the 6th YINI Summit in the context of the Nutrition 2018 Congress, on June 10, in Boston.
Professor Robert Hutkins from the University of Nebraska (USA) will focus on the specific role of live active bacteria of the yogurt.
A fermentation process that can provide additional properties to the food beyond basic nutrition
The popularity and increased consumption of yogurt, kefir, and other fermented dairy has been driven, in part, by the health benefits these products are thought to confer. Many of the nutritional attributes associated with these products, including, minerals, and vitamins are naturally present in the starting food materials. However, for fermented foods such as yogurt, the products of fermentation and the bacteria involved in the fermentation process, can provide additional properties to the food beyond basic nutrition. Among the most well-established effects is the role of yogurt bacteria in improving lactose digestion in individuals with lactose malabsorption.
“What benefits may be brought by fermented foods and fermentation processes? What are the effects on gut microbiome? Can yogurt or probiotic consumption improve gut microbiome and health?” are some of the questions addressed by Pr. Robert Hutkins during the Summit.
Who is Robert Hutkins?
Robert Hutkins is the Khem Shahani Professor of Food Microbiology in the Department of Food Science and Technology at the University of Nebraska. He received his B.S. and M.S. degrees from the University of Missouri and his Ph.D. from the University of Minnesota
The Hutkins Lab is focused on the studies of important bacteria in human health and in fermented foods. The lab is particularly interested in understanding how diet and various food components, especially microorganisms used in the manufacture of fermented foods and beverages, influence the bacteria that reside in the gastrointestinal tract. The lab is also focused on prebiotic fibers and how these food materials shift the intestinal microbiota in humans and animals and enhance human health.
Prof. Hutkins has presented many scientific seminars on probiotics and prebiotic, as well as lectures on fermented foods and other food science topics. He is also the author of the soon-to-be published 2nd edition of “Microbiology and Technology of Fermented Foods”.
Learn more with the presentation of its recent intervention on the health benefits of fermented dairy foods at the International Congress of Nutrition, in Nov 2017 in Buenos Aires.
Fermented dairy products such as yogurt, which has been associated with reduced risk of cardiovascular disease and type 2 diabetes, may be a source of magnesium.This review article shows that high dietary intake of magnesium is associated with a protection against cardiovascular risk factors including metabolic disease, type 2 diabetes (T2D), and hypertension, as well as against stroke and total cardiovascular diseases (CVDs).
Magnesium– also found in leafy vegetables, legumes, nuts and whole-grains – is an essential element in our diet that plays a crucial role in several biological processes, say the authors. So it comes as no surprise that changes in magnesium could have an impact on disease status.
Surveys have shown that many people in Europe and the USA fail to meet the daily allowance of magnesium, probably because of Western dietary patterns. Chronic deficiency of magnesium has been linked with several cardiometabolic conditions.
In this review, the authors highlight epidemiological data that contribute to a growing body of evidence pointing to an association between increased magnesium intake and reduced risk of cardiovascular disease (CVD).
Magnesium intake is associated with reduced risk of diabetes and other cardiovascular diseases (CVD) risk factors
Several observational studies have shown that higher magnesium intake is associated with a lower risk of type 2 diabetes (T2D). This is in a dose-response relationship, one study showing the risk of T2D was 8-13% lower per 100 mg/day of magnesium intakes.
Magnesium supplementation has been associated with a fall in insulin resistance, one of the underlying causes of the cluster of CVD risk factors that form the metabolic syndrome. Indeed, recent studies have suggested that higher intake of magnesium is associated with lower risk of metabolic syndrome.
In particular, evidence suggests high dietary magnesium may be linked to low blood pressure, while randomised controlled trials have suggested benefits of magnesium supplementation for improving lipid profiles in people with dyslipidaemia.
Dietary magnesium is associated with reduced cardiovascular diseases (CVD) events
As well as risk factors for CVD, dietary magnesium appears to be associated with reduced risk of cardiovascular events themselves, say the authors.
For example, population studies around the world have found a dose-dependent inverse association between magnesium intake and incidence of stroke.
Dietary magnesium intake also appears to play a protective role in the risk of death from total CVD and CV sub-types, especially in women, although the authors warn that the variability in the meta-analyses means the results should be interpreted with caution.
How does magnesium achieve these possible benefits on cardiovascular diseases risks?
The possible protective influence of magnesium intake on CVD risk may be achieved by improving glucose and insulin metabolism, and its effect on dyslipidaemia, as well as combating hypertension and inflammation, say the authors.
They conclude that the findings highlight the importance of eating enough magnesium-rich foods to help reduce CVD risk and prevent other chronic diseases. Further clinical research is needed to help clarify the relationship between magnesium intake and CVDs and CVD death.
The gut microbiota is gradually revealing its secrets. Its ecosystem contains about 1000 different species of microorganisms, which encode more genes than the human host and recent studies show its impact on several health issues… Review of the literature suggests that diet can modify the intestinal microbiome, which in turn has a profound impact on overall health. This impact can be either beneficial or detrimental, depending on the relative identity and abundance of constituent bacterial populations.
Yogurt live bacteria and their impact on gut health
Yogurt is characterized by its live microorganisms (Streptococcus thermophilus and Lactobacillus delbrueckii subsp. Bulgaricus), as well as strains of Bifidobacterium and Lactobacillus added specifically for their probiotic properties. Both culture organisms may benefit from the gut environment and, consequently, have an impact on health. These “probiotic” properties are of great interest for research. A recent study(1) report that regular consumption of yogurt appeared to increase the numbers of Lactobacilli. The microbial diversity also appears to increase slightly with yogurt consumption in some subjects.
The dairy matrix also matters! Still, dairy foods have long been the main delivery vehicle, and most probiotics do just fine in this matrix.
Clinical studies provide more and more evidence on the health benefits associated with yogurt consumption. For instance, yogurt bacteria, via the enzyme β-galactosidase they provide, improve lactose digestion, allowing people with lactose maldigestion to eat yogurt. Research also shows that yogurt containing probiotics improves intestinal and extra-intestinal health, and leads to improved immune and anti-inflammatory responses to infectious diarrhea and respiratory infections.
Not all fermented foods contain live organisms.
Beer and wine, for example, undergo steps that remove the organisms. Other fermented foods are heat-treated and the organisms are inactivated. Bread is baked and sauerkraut is often canned. So while these foods may be nutritious, they do not have probiotic activity, but may impact gut microbiota as well, as fermented foods.
Bio-active peptides and health benefits of yogurt
What could explain the health benefits of yogurt, reported by numerous epidemiological studies? Yogurt is a nutrient-dense food that contributes to the intake of protein, calcium, bioactive compounds and several micronutrients, which could help to explain some of its health benefits.
Dietary proteins can act as key regulators of immunometabolic factors and gut microbiota. Furthermore, during the fermentation process of milk with yogurt cultures, dairy proteins are cleaved, generating in smaller molecules that can have some biological effects. These bio-active peptides could explain the greater beneficial effect of yogurt on metabolic health compared with non-fermented dairy products, such as milk. For example, the fermentation of yogurt may lead to an increased production of bioactive peptides with physiologic effects such as increased insulin sensitivity and glucose tolerance. Several peptides or peptide fractions have also been investigated for their bioactive properties such as anti-hypertensive, anti-thrombotic, satiety, opioid, immuno-modulatory, osteogenic, and antioxidant activities. Fermented dairy peptides and especially yogurt-type peptides generally exerted greater anti-inflammatory effects than other dairy products. These immunometabolic effects are associated with major taxonomic changes in the gut microbiota. Whether specific bacterial species are modulated by peptides released from fermentation from dairy products remains to be determined. These newly proposed mechanisms require therefore more research before being validated as a key factor in the protection against CMD, like type 2 diabetes or obesity.
Yogurt is the best source of key bacteria
Yogurt and fermented milks are part of the most significant sources of viable bacteria (1 cup of yogurt = 10 8-10 bacteria). Despite the impact of fermented foods and beverages on the gut microbiota, their many health benefits or recommended consumption have not been widely translated to global inclusion in world food guidelines. In Europe, only one health claim (EFSA, 2010) has been approved for beneficial microbes: “live yogurt cultures improve lactose digestion”. The microbes contained in yogurt may also affect the function of the resident gut microbiota, even if they do not affect its composition, as it has been suggested by numerous studies. Indeed, the health benefits associated with the consumption of yogurt are more and more studied, and the importance of yogurt cultures Lactobacillus and Streptococcus in health promotion, by strengthening the intestinal mucosal barrier for example, have been recognized.
As latest research questions conventional dietary recommendations on dairy foods due to the properties of dairy fats, fermented dairy products such as yogurt, cheese and kefir, could prove to be a healthy choice for protecting against cardiovascular disease (CVD).
Dairy foods have long been believed to increase the risk of CVD due to their fats content and their association with increased cholesterol levels. In response, dietary guidelines in Western countries recommend limiting full-fat dairy products in favour of low-fat versions.
However, with recent evidence suggesting that systemic inflammation is the key biochemical driver of atherosclerosis and damage to the heart muscle, this advice and the science underlying it are now under debate, according to the authors of this review article.
High saturated fatty acid intake may not cause harmful cholesterol levels
Question marks have been raised over the science that suggested a causal relationship between a high intake of saturated fatty acids (SFA), high LDL-cholesterol, atherosclerosis and coronary heart disease.
Indeed, the authors say, despite high levels of SFAS, full-fat dairy foods have positive or at least neutral effects on cardiovascular health, while also contributing to higher intakes of nutrients such as vitamins D and K.
The focus is shifting to consider the effect of the fermented dairy food matrix on cardiovascular health
Research has moved away from focusing on single nutrients, such as saturated fat, towards considering the food matrix, the nutrient and non-nutrient components of foods and how they interact and affect body chemistry.
Researchers are also trying to pin down the specific effects of different types of dairy foods, including fermented products, such as yogurt, cheese and kefir, on cardiovascular health.
Fermented dairy products such as yogurt may hold potential benefits for cardiovascular health
Although fermented dairy products are often linked with gut health, they also appear to benefit cardiometabolic health, which encompasses cardiovascular and metabolic diseases, including type 2 diabetes (T2D) and the metabolic syndrome.
Higher consumption of cheese, yogurt and kefir is linked with lower levels of LDL-cholesterol and blood pressure, together with a lower risk of T2D, stroke and coronary heart disease (CHD). These potential benefits may increase the more you consume.
Yogurt in particular is associated with a reduced risk of cardiovascular diseases (CVD)
Yogurts in particular, with their diverse assortment of different bioactive, nutrient-rich compounds, especially when consumed with fruit, have been linked with a reduced risk of CVD, diabetes and metabolic syndrome – i.e. high blood pressure, high blood glucose, large waist circumference and abnormal blood fats.
Choose fermented dairy products to optimise nutrient intake and potential cardiovascular health benefits
Exactly how fermented foods influence risk factors for CVD is yet to be uncovered. However, it is thought that probiotics and vitamin K2, which are both present in fermented dairy foods, may play a part.
The fermentation process itself may also have a role as it leads to changes in the structure of fats and proteins. These may account for some of the observed effects. There may also be benefits of full-fat dairy consumption based on higher bioavailability of high-value nutrients and anti-inflammatory and antioxidant properties.
Hence while full-fat dairy products can continue to be consumed in moderation as part of a healthy balanced lifestyle, choosing fermented dairy products is most likely to optimise nutrient intake and potential cardiovascular health benefits.
Infants who are given yogurt to eat every day may be less likely to suffer from eczemadue to a reduced skin hypersensitivity to histamine.
Atopic eczema (atopic dermatitis) is the most common form of eczema, often arising before a child’s first birthday.
Previous reports have suggested that consuming probiotics during the perinatal and postnatal periods is associated with a reduced risk of atopic eczema in the infant, but until now it hasn’t been known why. The authors of this study aimed to discover what the mechanism might be.
The authors’ hypothesis was based on reports that probiotic consumption is not associated with risks of other allergic conditions and does not appear to affect levels of IgE (immunoglobulin E), the antibodies that lead to an allergic reaction. Their preliminary results suggest that daily yogurt consumption may reduce skin hypersensitivity to histamine – thereby possibly reducing risk of eczema during infancy.
Mother and infant pairs were tested for skin hypersensitivity
To investigate whether probiotics could be reducing skin hypersensitivity, the authors carried out a cross-sectional study of 256 mothers with babies aged up to 6 months.
The mums were asked to complete questionnaires about food consumption perinatally and postnatally, and skin prick tests were used to assess skin response to histamine.
Daily yogurt consumption in infancy was associated with a reduced skin hypersensitivity to histamine
Infants who had eczema showed a larger skin reaction to the histamine – as shown by the size of their wheals on the skin prick test – than those who did not have eczema.
Among those without eczema, the reaction to the skin prick test was less in those who consumed yogurt daily than in those who did not.
No association was seen between perinatal consumption of yogurt by the mothers and skin prick reactions, either in the mothers or their infants.
The authors conclude that these preliminary findings point to the need for further research into the potential role of probiotic / yogurt consumption in regulating skin hypersensitivity to histamine.
Dairy foods are high in saturated fats and yet may have a protective effect against cardiovascular diseases.
In the EU, 49 million people are living with cardiovascular diseases (CVD), which remains a major cause for concern. Dietary guidelines targeting CVD risks have tended to restrict the intake of saturated fats because of their association with raised blood cholesterol and some proposals have advised restricting dairy foods as, major sources of saturated fats. However, recent studies (1,2) indicate that such an approach would be over-simplistic.
Evidence suggests dairy does not raise CVD risk
Despite their high saturated fatty acids (SFA) content, dairy foods have repeatedly been found to have either no effect, or a beneficial effect on Cardiovascular diseases risk(1). Meta-analyses of prospective studies show that drinking milk does not increase the relative risk of coronary heart disease compared with low milk consumption. Other meta-analyses have shown no increase in CVD risk – and a fall in risk of stroke – per unit increase in milk and cheese consumption. Furthermore, yogurt consumption has been associated with a reduced risk of type 2 diabetes.
The health benefits of the whole dairy matrix may offset the risks of cardiovascular diseases
The lack of increased risk of cardiovascular diseases among high dairy consumers may be due to the protective properties of other components that counter-balance the effects of SFAs. The health effect of a food may depend less on the individual effects of its nutrients and more on the overall effect of the food as a whole matrix.
Milk and dairy products are rich in micronutrients and proteins, such as whey protein, which have been shown to lower blood pressure. Milk proteins may also have a beneficial effects on blood lipids, although further research is needed to confirm this. Research has also suggest that dairy product consumption does not increase arterial stiffness, an important predictor of CVD events.
The dairy matrix may have specific beneficial effects. Different types of dairy seem to be linked to various health effects while different processing methods may enhance interactions in the dairy matrix and so alter the metabolic effects. Hence, in a crossover study, cheese did not lower total cholesterol or LDL-c relative to baseline, whereas butter increased both.
What about the effects of full-fat yogurt?
Yogurt is a nutrient-dense food within the dairy group and is fermented, bringing live culture bacteria. Yogurt contains several bioactive fats(2): Medium-chain fatty acids (MCFAs) in yogurt are a source of rapid energy and not likely to be deposited as fat in the body. MCFAs have been associated with anti-diabetes effects, including improved glucose tolerance, protection against insulin resistance and preserved insulin action. Conjugated linoleic acid (CLA) has been linked with anti-obesity effects, and improved metabolic parameters associated with type 2 diabetes.
It is also likely that the calcium, protein, bioactive nutrients and live cultures contained in yogurt are responsible for its beneficial effects of yogurt on CMD risk. However, further research is needed to discover the individual roles of these nutrients and how they work together in the food matrix.
A larger review of the science on the beneficial effects of the yogurt and its fermented dairy matrix will be made in June 2018, during the next YINI global summit: “Yogurt, more than the sum of its parts”
A wealth of research is shedding light on how fermented dairy foods such as yogurt and cheese may be associated with reduced risk of cardiometabolic disease, including cardiovascular diseases (CVDs), stroke, and type 2 diabetes, according to the authors of this review.
Official dietary recommendations for dairy foods tend to be based on the impact of single nutrients or types of product on health – for example, advising low-fat products to avoid weight gain or reduce saturated fat to lower the risk of heart disease. But now a much more complicated picture is emerging of the many ways in which dairy foods may be associated with reduced risk of cardiometabolic disease, a term that encompasses cardiovascular and metabolic conditions such as insulin resistance and type 2 diabetes. The authors of this review of lab-based research, animal studies and human trials argue that both well-known and lesser-known components of dairy foods, as well as processing methods such as fermentation, can affect biological pathways and through them lead to benefits for cardiometabolic health.
Potential cardiometabolic benefits of dairy proteins are emerging
Cow’s milk proteins, mainly casein and whey, have been associated with improving cardiometabolic health, for example by helping to maintain the correct balance of blood glucose and insulin levels, at least in animals.
This may be linked to specific amino acids and/or naturally occurring bioactive peptides released during fermentation.
Traditional dietary guidelines obscure the potential benefits of dairy fats on cardiometabolic disease
High blood levels of dairy fatty acids are consistently associated with a reduced incidence of diabetes and possibly coronary heart disease and stroke in cohort studies.
The authors say that the traditional emphasis on saturated fats and high levels of LDL-cholesterol in dietary guidelines has obscured the potentially positive effects of dairy-derived saturated fatty acids on, for example, HDL-cholesterol.
This emphasis also downplays the potential benefits of other types of fatty acids and lipid components that make up most of the fat content of milk. These include a variety of saturated, monounsaturated and polyunsaturated fatty acids, as well as bioactive compounds found in the Milk Fat Globule Membrane (MFGM) that surrounds fat droplets in milk.
Benefits may also come from fat-soluble vitamins D, K, and K2, produced from dairy fats during fermentation.
Probiotics in fermented dairy products may help prevent cardiometabolic disease by promoting changes in gut microbiota
The review shines a spotlight on growing evidence of the links between probiotics in fermented dairy products, such as yogurt, and changes in the gut microbiota.
This interaction between probiotics and the gut microbiota may confer a protective effect of dairy fermented food against weight gain, obesity and metabolic conditions such as diabetes.
The potential role of fermentation and vitamin K2 in cardiometabolic risk is a promising new area of research
The authors draw links between vitamin-K2-producing bacteria, used in the production of fermented dairy products, and the potential to reduce the risk of cardiometabolic diseases. This represents a promising area for further research.
Yogurt is associated with reduced cardiometabolic conditions, such as long-term weight gain and diabetes
The associations between dairy intake and reduced risk of overweight, heart disease and diabetes may depend more on the type of product than its fat content, say the authors:
Yogurt, for instance, seems consistently to be associated with reduced long-term weight gain – even when sweetened with sugar – compared with low-fat or whole milk.
Cheese seems to have a relatively neutral association with weight gain.
Both yogurt and cheese are also associated with a lower risk of type 2 diabetes, adding further strength to the evidence that fermentation may be a key factor in cardiometabolic health.
Traditionally, the nutritional evaluation of the relation between diet and health has focused on individual food constituents or nutrients separately. This approach, which links one nutrient to one health effect, may partly explain some of the discrepancies between a food’s predicted health effect based on its nutrient content and its actual health effect, when consumed as a whole food.
A diet does not consist of single nutrients
The food matrix is defined as “the nutrient and non-nutrient components of foods and their molecular relationships, i.e. chemical bonds, to each other” (cf. National Agriculture Library, USDA). Foods have complex structures, which affect digestion and absorption and may generate interactions within the food matrix, there by altering the bioactive properties of nutrients in ways that are not predictable from the nutrition-label information. This appears more and more evident for the dairy matrix.
The dairy matrix has higher beneficial effects on health than single nutrients
There are differences between the metabolic effects of a whole dairy, and those of single dairy constituents, on body weight, cardiometabolic diseases (CMD) risk or bone health. For instance, despite the high level of saturated fatty acids in dairy fats, experts(1) agree that there is no association between the intake of dairy products and the risk of CMD or even with type 2 diabetes. They also pointed to the fact that the relationship between dairy and health differs, according to the subtype of dairy product. In addition, different processing methods and dairy structures can enhance interactions in the dairy matrix, thereby modifying the metabolic effects of dairy consumption. Therefore, the nutritional value of dairy products should be considered as the biofunctionality of the sum of nutrients within dairy matrix structures.
The yogurt matrix may play an important role in protecting against cardiometabolic diseases (CMD)
Observational studies shows that yogurt consumption is associated to a reduction of the risks of obesity and type 2 diabetes, and accumulating evidence supports the role of yogurt consumption in weight management. Yogurt appears to have a neutral effect on the risk of heart and vascular diseases. In a recent review(2), the authors discuss the possible mechanisms underlying the association found by these studies and point out the potential effect of the yogurt matrix.
The yogurt matrix may play an important role in boosting the health benefits of its nutrients. The gel structure of the matrix may protect its nutrients and bioactive compounds against degradation and allow improved nutrient interactions. It may be responsible for the reduced incidence of type 2 diabetes in people who eat yogurt compared with milk and other dairy products.
The fermentation process and live bacteria of yogurt may also bring health benefits. Yogurt is believed to have positive effects on the gut microbiota and intestinal barrier function – these effects may contribute to its cardiometabolic health benefits. Indeed, unbalanced gut microbiota (dysbiosis) and impaired intestinal barrier function can contribute to obesity, inflammation and type 2 diabetes. Consuming yogurts with live cultures may have important beneficial effects on maintaining a healthy and balanced gut microbiota. Moreover, bioactive peptides released during yogurt fermentation have cardiometabolic health effects: blood pressure-lowering, cholesterol-lowering, anti-thrombotic, anti-oxidant, mucin-stimulating, and immune modulating activities. Bioactive peptides may also help to improve insulin sensitivity.
Yogurt contains also several bioactive fats and high-fat yogurt consumption has been associated with a reduced risk of CMDs. For example, medium-chain fatty acids (MCFAs) in yogurt have been associated with anti-diabetes effects and conjugated linoleic acid (CLA) have been linked with anti-obesity effects, and improved metabolic parameters associated with type 2 diabetes. Yogurt is also good source of calcium, which may also help to prevent type 2 diabetes through mechanisms that reduce nutrient deficiencies, control high blood pressure, prevent obesity and reduce inflammation.
Last but not least, positive effects of yogurt on CMDs have often been attributed to the potential for yogurt to increase satiety, which may be due in part to its protein content.
The beneficial effects of dairy proteins on glucose regulation, which could explain a protective effect on T2 Diabetes risk
The protein quantity and quality are contributing factors to their effects on glucose control. As foods are much more complex than a single nutrient, many factors (nutritive and/or bioactive), mediate the relationship between food intake and health. This is particularly the case with the food matrix of dairy products.
Protein ingestion can increase the ability to secrete insulin, and the ability to modulate insulin secretion and sensitivity varies with the source of protein. There are many more factors involved in glycemic management than just insulin, such as incretin hormones (synthetized by the gut). Among animal-based proteins, certain subtypes show negative, and other show neutral or positive effects on type 2 diabetes risk. A review(3) point out that a higher intake of dairy products (milk, yogurt, cheese and whey proteins) consistently shows a beneficial relationship with glucose regulation and type 2 diabetes risk reduction.
If dairy proteins have more effects on insulin and incretin secretion compared to other animal proteins, the authors(3) underlines the interest of the food matrix of dairy products, contening several components which exerts beneficial effects on glucose control, insulin secretion and sensitivity. These components are among others: calcium, magnesium, potassium, trans-palmitoleic fatty acids, and sugars with low-glycemic index.
These results shows that further focus on product types, characteristics and protein properties are necessary to better determine a product’s glucoregulatory abilities.
A larger review of the science on the beneficial effects of the yogurt and its fermented dairy matrix will be made in June 2018, during the next YINI global summit: “Yogurt, more than the sum of its parts”
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