Funded under the National Recovery and Resilience Plan (NRRP), Mission 4 Component 2 Investment 1.3, Theme 10.
Mentorship programSpoke 04
Is Milk Really the Cause of Bloating? The Answer Lies in Digestion!
A study suggests the issue isn’t the milk itself but how it’s digested, highlighting the role of diet in improving tolerance and reducing discomfort.
Silvia Tagliamonte
Researcher in Physiology
Published: December 13, 2024
Share:
Today, it’s widely believed that cow’s milk should be avoided at a certain point in life, as it can cause gastrointestinal discomfort. However, as a study from the University of Naples suggests, the real difference isn’t so much the milk itself but rather how we digest it, which varies from person to person and is influenced by our regular diet.
Milk consumption in Italy has dropped significantly over the past few decades. Between 1998 and 2020, the percentage of people drinking milk daily fell from 62.2% to 48.1%. Particularly, among children aged 3 to 10, the habit of having milk for breakfast dropped by about 20 percentage points, from 56.6% to 45.6%.
The reasons behind this decline - which many of us can observe firsthand in our own households - are varied, including cultural, dietary, and lifestyle shifts. Some key factors include the rise of plant-based alternatives seen as healthier and more sustainable than animal milk, busier lifestyles that disrupt breakfast habits at home, and changing food preferences that lead especially younger generations to replace milk with other beverages.
Additionally, we need to consider the role of information, which is not always scientifically accurate, in shaping beliefs about the link between milk consumption and gastrointestinal issues.
Gastrointestinal issues like bloating, gas, abdominal cramps, and a general feeling of heaviness are common for many people and can be triggered by various dietary and digestive factors, including milk consumption. Milk, as we know, has long been a staple in human diets. On the one hand, it’s a rich source of essential nutrients - containing calcium, proteins, vitamins, and minerals crucial for the health of bones, muscles, and the body overall. On the other, many people experience digestive discomfort after consuming it, leading to the idea that, at a certain age, it’s best to stop drinking milk, which has overshadowed scientific evidence highlighting its numerous health benefits.
But is this really the most sensible choice?
A recent study by the University of Naples Federico II suggests that the real issue isn’t the milk itself but rather how it’s digested. The good news is that, with a personalized diet that adapts to each person’s unique physiological needs, it’s possible to “retrain” the digestive system, improving tolerance to this food.
People who report gastrointestinal symptoms after drinking milk often believe they are lactose intolerant, even without a formal diagnosis. But what’s the real cause? One possible explanation lies in our body’s ability to digest milk proteins effectively, including caseins and whey proteins. During digestion, these proteins break down and release bioactive peptides - compounds that can have both positive and negative effects on different biological systems. Researchers from the Department of Agricultural Sciences at the University of Naples Federico II conducted a clinical study with healthy, non-lactose-intolerant participants: 20 regular milk drinkers who reported no gastrointestinal issues after consuming milk, and 20 non-regular drinkers who avoided milk due to such symptoms. “The results showed that people experiencing gastrointestinal discomfort linked to milk digest its proteins differently,” explains Professor Paola Vitaglione, a physiology expert at the University of Naples Federico II, “releasing a higher amount of peptides with opioid activity, which can affect intestinal motility by slowing gastric emptying and intestinal transit.”
These peptides, as hypothesized in the study, bind to opioid receptors in the gastrointestinal tract, altering normal transit. The result? A slower, less efficient digestive process that can cause an uncomfortable feeling of heaviness.
Do We All Digest in the Same Way?
But that’s not all. Our ability to digest milk is also strongly influenced by the composition of our gut microbiome - the complex community of bacteria in our intestines that plays a crucial role in food digestion.
The microbiome is unique to each person and adapts based on our dietary habits. Those who regularly drink milk without issues often have a different bacterial profile compared to those who struggle to digest it and thus reduce their intake. In regular milk consumers, the microbiome is often rich in bacteria that efficiently break down milk proteins, enabling quicker and smoother digestion. In contrast, those who rarely drink milk or avoid it out of concern for gastrointestinal discomfort may have a microbiome that’s less “suited” to digesting this food. This can lead to an accumulation of undigested proteins in the intestine, resulting in symptoms like bloating, abdominal pain, and gas.
This discovery is significant because it shifts the focus from milk itself as a possible “culprit” to the individual physiological processes that determine how we respond to foods. Milk isn’t inherently problematic; rather, it’s each person’s unique ability to process and digest it that makes the difference.
And this isn’t unique to milk: the same principle can apply to many other foods. What one person tolerates well may be a real challenge for another’s digestive system.
This is where interindividual variability comes into play, explains Professor Paola Vitaglione. The way each of us digests food depends not only on the composition of our gut microbiome but also on a range of genetic and environmental factors that influence how various biological systems function and interact with the microbiota itself.
This variability helps explain why there isn’t a one-size-fits-all diet. Each of us has a unique body with different needs and responses to the same foods. For some, milk may be an excellent source of nutrients and easy to digest. For others, it might be more challenging - not because of the milk itself but due to the specific traits of their digestive system. The key concept, then, isn’t to demonize a particular food, but to understand how it interacts with our physiology and to recognize the unique characteristics of our bodies that determine our tolerance.
Toward a Personalized Diet: Why Nutrition Should Be Tailored
In light of all this, the importance of a personalized approach to nutrition is becoming ever clearer. In an era where we increasingly discuss personalized medicine and nutrition, recognizing your body’s uniqueness is essential. Instead of cutting milk or other foods out of your diet entirely, it may be beneficial to explore alternative solutions currently under research. In fact, scientific research is increasingly focusing on developing customized foods designed to meet each individual’s specific needs, using innovative and sustainable technologies to improve food quality.
Research projects within Spoke 04, for instance, aim not only to enhance food quality through innovative formulations - such as postbiotics (https://onfoods.it/research-projects/development-functional-legume-based-foods-and-ingredients-through-fermentation) - but also to expand knowledge in the field of personalized and sustainable nutrition that accounts for the vast individual variability in dietary responses (https://onfoods.it/research-projects/discovering-effects-pulses-through-gut-microbiome-and-bioavailability-bioactive). Thanks to advanced knowledge gained through studying the microbiome, genetics, and precision nutrition, we may soon be able to design personalized diets that “retrain” the digestive system, making digestion more efficient and reducing discomfort linked to certain foods.
These approaches aim to provide concrete solutions for those who, like milk consumers, experience discomfort related to specific foods, enabling them to enjoy the nutritional benefits. The future of nutrition and food technologies is therefore heading toward greater consumer awareness and food personalization, with the goal of promoting individual well-being while respecting each person's biological uniqueness.
Silvia Tagliamonte
Researcher in Physiology
Silvia Tagliamonte is a researcher on a fixed-term contract at the Department of Agriculture of the University of Naples Federico II, in the scientific-disciplinary sector BIOS-06/A - Physiology. Her research focuses on the digestibility of proteins, carbohydrates, and fibers, as well as the bioaccessibility and/or bioavailability of phytochemicals from various matrices, using in vitro studies and human clinical trials
This blog post is related to
Food quality and nutrition
To push towards sustainable and tailored food and nutrition
Lead organisation
Spoke leaderPatrizia Riso
Research projectDE LEGUMINIBUS
Principal investigators
Paola Vitaglione,Danilo Ercolini,Luisa Cigliano
Referred to
Spoke 04