Today we will talk about LACTOSE INTOLERANCE, a physical condition characterized by the inability to digest milk sugar. Before starting the description of lactose intolerance, let us briefly summarize what the word INTOLERANCE means and what LACTOSE is.
By FOOD INTOLERANCE, or rather, FOOD INTOLERANCE, we mean the IMPOSSIBILITY to digest a specific nutrient. This predisposition, if ignored, can trigger a TOXIC reaction characterized by some GASTRO-INTESTINAL DOSE-DEPENDENT symptoms. Food intolerance IS NOT AN ALLERGY !!! Which, on the contrary, ALWAYS provides for the triggering of an IMMUNE-MEDIATED reaction and is NOT DOSE-DEPENDENT.
Lactose is a DISACCHARIDE SUGAR, or an OLIGOSACCHARIDE composed of TWO DIFFERENT UNITS: one of GLUCOSE and one of GALACTOSE. These two MONOMERS are united by a chemical bond of the BETA 1-4 GLYCOSIDE type, which should be CLOSED in the INTESTINAL digestion or in the BACTERIAL fermentation.
Lactose is the typical sugar of milk and some of its derivatives. In fact, not all milk by-products contain CONSIDERABLE doses of lactose; usually, the long fermented and seasoned ones can benefit from the bacterial hydrolytic action and are ALMOST totally devoid of it, while the FRESH and LITTLE (OR NOTHING) fermented (called DAIRY) bring significant quantities.
Lactose intolerance is NOT a disease, but rather a PHYSICAL CONDITION! This is the lack of an INTESTINAL ENZYME of the SPECIFIC HYDROLASE-DISACCARIDASE type: that is the BETA-D-GALACTOSIDASE, more commonly called LACTASE! Not surprisingly, the scientific term for lactose intolerance is IPOLACTASIA. Lactase is a real BIOLOGICAL CATALYST and is found on the BRUSH LETTER of the ENTEROCYTES (ie the cells of the mucosa) placed at the extremity of the VILLI of the SMALL INTESTINE. If a subject who does NOT have enough lactase (i.e. LESS than 50% of necessary) takes too much lactose compared to HIS digestive capacity, this is NOT digested and triggers a symptomatology that we will see in the next slides.
Lactase is TYPICALLY expressed in the child's intestine up to the 6th month of life. Thereafter, it can either DECREASE until it disappears, or PERSIST at lower concentrations BUT for life. This VARIABLE depends on many factors, including: heredity, subjectivity, ethnic group and maintenance of enzymatic trophism (in practice, it is as if the enzymes have to be kept in "training"). The populations that most CONSERVE lactase are those that colonize Northern Europe, while the global average documents the preservation of the enzyme in adulthood which is around 30%. This means that about 70% of the population demonstrates a NON PERSISTENCE of lactase ... even if Luckily a good part of these people DO NOT feel the specific clinical characteristics. Lactose intolerance can manifest itself in 3 different ways, namely: CONGENITAL form, PRIMARY form and SECONDARY form. The congenital form immediately affects the newborn and manifests itself with WATER DIARREA, malabsorption and growth retardation. The primary form, also genetically determined, is the most common and is based on the loss of the enzyme over the course of life. The secondary form can have various triggering causes, including: Crohn's disease, celiac disease, radioactive exposure, autoimmune reactions, certain infections, certain drug treatments and certain post-surgical conditions. Then, it is essential to underline that some of the forms of secondary lactose intolerance can be of the TRANSITIONAL type, that is, they stop at the time of the primary pathological resolution; a classic example of this periodic intolerance is viral or bacterial gastro-enteritis hypolactasia.
At this point, many listeners will ask themselves:
WHY are some people able to express lactase for life and others BECOME intolerant?
The answer is quite simple and has prehistoric origins. The first human creatures appeared on earth about 3.5 million years ago; however, HOMO SAPIENS SAPIENS (ie the most evolved form, the contemporary one) only began to master breeding techniques 8-9 thousand years ago. Given and considering that the use of animal milk began ONLY after breeding, it is possible that (from an evolutionary point of view) the time span elapsed is still insufficient!
As we have already said, lactose intolerance occurs after the ingestion of milk, dairy products or foods that contain them, through a TOXIC GASTROENTERIC type symptomatology and NOT of the RESPIRATORY or SKIN type, instead typical of the ALLERGY to MILK PROTEINS .
The complication mechanism is quite simple: by not digesting lactose, it accumulates in the distal portion of the small intestine and (by osmotic effect) draws water and sodium from the mucosa causing diarrhea. Later, when the lactose reaches the colon, the physiological bacteria metabolize it producing some gases such as: METHANE, HYDROGEN, CARBON DIOXIDE and VOLATILE FATTY ACIDS, which (obviously) manifest themselves as: FLATULENCE, ABDOMINAL DISTENSION AND SENSE OF SWELLING. Sometimes, by reflex action, NAUSEA and VOMITUS can also arise.
The doubt of lactose intolerance must arise with the manifestation of diarrhea. However, it must be specified that a part of the lactose intolerant population does NOT know they are, as they DO NOT manifest intestinal reactions so important as to start a diagnostic process for hypolactasia! on the other hand, the absence of symptoms completely nullifies the need for LACTOSE EXCLUSION therapy since, without diarrhea, there is not even a reduction in food absorption.
In case of "well founded suspicions" instead, it is advisable to carry out specific diagnostic tests in order to recognize a possible lactase deficiency. The first analyzes coined for this need were real glycemic tests and were based on the principle that IF lactose is digested and then absorbed, after its intake there should be an increase in blood glucose. On the contrary, it indicates a positivity to hypolactasia. Very precise and specific, but invasive to say the least, is the intestinal biopsy of the FASTING portion, in which a sample of tissue is taken to be analyzed to check the density of the lactase contained in it. Today, the exam considered GOLD-STANDARD is the BREATH-TEST, or breath test. It is non-invasive and easy to perform. As for the glycemic load, we proceed with the intake of a certain amount of lactose after which, every 30 'for 3 or 4 hours, the gases from the EXHAUSTED AIR are analyzed. If there is much more HYDROGEN than normal (respectively produced by the bacteria of the colon and absorbed by the mucosa), the test is considered POSITIVE. Other tests much less used today (or used in the diagnosis of lactose intolerance in the newborn) are: the analysis of the FAECAL pH, the determination of the FECAL REDUCING POWER and the CHROMATOGRAPHY of the FAECAL SUGAR PAPER.
It is logical that, in the event of severe intolerance, the only solution is the abolition of lactose from the diet. On the other hand, some gastro-enterologists consider periodic SUSPENSION followed by a GRADUAL reintroduction useful. In fact, it seems that the INTAKE of about 5-10g of lactose per day, associated with foods that are able to slow down intestinal transit, can favor the restoration (perhaps partial) of sugar tolerability. For many listeners this behavior may seem unwarranted:
Why, in adulthood, try to drink milk if it is not digestible?
First of all because, unlike CELIAC, lactose intolerance does not hide SEVERE complications! Furthermore, milk and dairy products are VERY important foods due to their content in calcium, vitamin B2 and galactose. Ultimately, taking SMALL amounts every day (obviously, in the ABSENCE of diarrhea) represents a discrete nutritional ADVANTAGE.
At the moment there is NO CURE and the only way to avoid the manifestation of symptoms is the EXCLUSION or REDUCTION of lactose in the diet. Fortunately, there are several FOOD ALTERNATIVES (some modern, others ancient) that are very useful for the intake of milk and derivatives by the intolerant. These are: MILK with a REDUCED PERCENTAGE of LACTOSE (or DELACTATED milk for added enzymatic action), and fermented dairy products such as: yogurt, Greek yogurt, kefir and buttermilk. These products do not cause the accumulation of fermenting lactose and, consequently, in addition to preventing diarrhea, they do NOT seem to increase the amount of GAS typical of intolerance symptoms. Furthermore, the intake of probiotic microorganisms with fermented dairy products exert a positive action on the bacterial flora, contributing to the intestinal readjustment of lactase.
Dairy products that must be avoided, or taken in quantities inversely proportional to the degree of intolerance towards lactose are: milk from any animal, cottage cheese or cottage cheese, yogurt, cream, ricotta, melted cheese, emmenthal, crescenza, etc. Obviously, all the products that contain them such as: milk chocolate, ice cream, custard, bechamel etc. must also be moderated with them.
