- The human body is not just made up of isolated compartments like the mouth, stomach, and intestines, but also includes structures like the tubarial salivary glands, the interstitium, and the mesentery that play crucial roles in nutrition and metabolism.
- The tubarial salivary glands, located near the nasopharynx, help keep the area moist and lubricated for swallowing, highlighting the importance of saliva in digestion and the potential impact on food intake in patients undergoing head and neck radiotherapy.
- The interstitium serves as a network of fluid-filled spaces that facilitate the exchange of nutrients between cells and tissues, emphasizing the complex distribution system involved in nutrition beyond just digestion and underscoring the importance of staying hydrated for cellular health.
When we think about nutrition, we almost always picture the same key players: the mouth, stomach, intestines, liver, pancreas and, perhaps, the gut microbiota. However, the human body is not made up of isolated compartments. Eating is not just about introducing food into the digestive tract, it also involves salivating, swallowing, transporting, distributing fluids, activating defences, moving fats through the lymph, connecting tissues and supporting organs
In recent years, three body structures have attracted particular interest: the tubarial salivary glands, the interstitium and the mesentery. All three demonstrate that nutrition, hydration, absorption, transport, immunity and metabolism are closely linked
Tubarial salivary glands: eating well means swallowing well
In 2021, researchers identified previously unnoticed glandular structures at the back of the nasopharynx – near the region where the Eustachian tube opens. These glands did not fit with classical anatomical descriptions
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The tubarial salivary glands, as they came to be known, do not digest fats, do not absorb amino acids and do not regulate glucose, but they may play a role in something far more fundamental. They seem to keep a key area for swallowing moist and lubricated – but this area is not in the mouth
Saliva contributes to the earliest stages of digestion. It helps to form a bolus of food, enables swallowing, plays a part in taste, and protects the mucous membranes. When its production or distribution is disrupted, it can cause symptoms like a dry mouth (xerostomia), difficulty swallowing (dysphagia), changes in taste, and a reduced appetite. In patients with head and neck cancer, these changes can significantly affect their food and nutrient intake
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For this reason, the tubular salivary glands are of particular interest in head and neck radiotherapy. If a glandular area is irradiated without recognising its potential function, this could lead to side effects. From a nutritional point of view, this is hugely important – a person who cannot swallow properly cannot eat properly. These recently discovered glands are a reminder that nutrition begins before the stomach
Interstitium: the fluid where your cells live
The interstitium can be described as a network of fluid-filled spaces within and between tissues. When it was discovered in 2018, many media outlets reported it as a “new organ”. This label has been disputed, but what matters is not so much the name as the concept: interstitial fluid is not just a passive filler between cells
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From a nutritional perspective, it can be understood as a site of exchange. Nutrients absorbed in the intestine enter the bloodstream, but to reach many cells they must pass through the extracellular space, where water, electrolytes, glucose, amino acids, fatty acids, immune signalling molecules, metabolites and waste products (among many other things) move about
Nutrition does not end when nutrients cross the intestinal wall, but how do nutrients actually reach the tissues? The answer involves blood, lymph, the endothelium (the inner lining of blood and lymphatic vessels), the extracellular matrix (the network that supports and connects cells) and interstitial fluid itself. It involves a complex distribution system that is often overlooked in simplified nutritional advice
The body’s water is not found solely in the blood or even inside cells, it is distributed across different areas. That is why staying hydrated and following a proper diet goes far beyond digestion, to directly impact the fluid environment in which our cells live
Mesentery: a nutrient highway from the intestine
Until recently, it was believed that the third of our protagonists, the mesentery, consisted of a series of folds that held parts of the intestine in place. However, a 2022 anatomical study revealed that it is in fact a structure with its own functional identity
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It is true that the mesentery supports the intestine, but it also does much more: it contains blood vessels, lymphatic vessels and lymph nodes, nerves, and adipose tissue. It is, in short, a highway between the intestine and the rest of the body
Its nutritional importance is indisputable. After digestion, many nutrients pass into the bloodstreament route: to transport them, the intestine converts them into particles called chylomicrons, which pass into the lymphatic system and, from there, into the bloodstream
The mesentery also plays a role in our immune systems. The intestine is constantly exposed to food, bacteria, metabolites and foreign molecules. Consequently, the immune tissue associated with the intestine must learn to tolerate what is beneficial and respond to what is harmful. The mesentery plays a part in this interaction between diet, the microbiota, immunity and inflammation
The mesentery is not just an anatomical feature: it is metabolism organised within tissue itself
New ways of understanding nutrition
These three body areas do not change basic nutrition recommendations, but they do enrich the way we explain nutrition. They force us to move away from a view focused solely on nutrients towards an anatomical, integrated perspective
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The tubarial glands remind us that eating requires saliva, lubrication and swallowing; the interstitium, that water and nutrients must circulate between cells and tissues; and the mesentery, that absorption is not merely a matter of passing through the intestinal wall – it also involves transport, defence and communication
Perhaps the most interesting point is that nutrition is not confined to your dinner plate and gut. On the contrary; eating is a comprehensive process that involves the entire body
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Este artículo fue publicado originalmente enThe Conversation, un sitio de noticias sin fines de lucro dedicado a compartir ideas de expertos académicos
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José Miguel Soriano del Castillo no recibe salario, ni ejerce labores de consultoría, ni posee acciones, ni recibe financiación de ninguna compañía u organización que pueda obtener beneficio de este artículo, y ha declarado carecer de vínculos relevantes más allá del cargo académico citado
