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Lactose Intolerance

Lactose intolerance (lactase deficiency, hypolactasia) is the inability or insufficient ability to digest lactose due to low levels of lactase. Abdominal bloating, abdominal pain, diarrhea and flatulence are common symptoms.


Presentation

The symptoms depend on the quantity of lactose ingested and the ability of the body to digest the amount of lactose. This in turn depends on the extent of lactase deficiency.

The main symptoms presented by the patients are abdominal fullness or bloating, nausea, abdominal pain, diarrhea and flatulence [11]. Borborygmi may also be experienced.

On physical examination, the abdomen may be tender. One may feel the bloating of the abdomen. Auscultation may reveal borborygmi sounds.

Euthyroid
  • Thirty-eight patients with LI (30 euthyroid and 8 with subclinical hypothyroidism), and 12 patients without LI were included in the final analysis.[ncbi.nlm.nih.gov]
  • In patients after gastro-intestinal tract surgery, a dose of LT4 higher than that typically used is needed to restore euthyroidism.[ncbi.nlm.nih.gov]
  • However, an abnormality in the bioavailability of LT(4) should also be considered in patients requiring large doses of LT(4) to achieve euthyroidism.[ncbi.nlm.nih.gov]
Noncompliance
  • The most common cause of apparent ineffectiveness or resistance to treatment with oral levothyroxine (LT(4)) is the result of noncompliance, known as pseudomalabsorption.[ncbi.nlm.nih.gov]
  • PATIENTS: The replacement T4 dose has been analyzed, from 2009 to 2012, in 34 hypothyroid patients due to Hashimoto's thyroiditis and lactose intolerance and being noncompliant with a lactose-free diet.[ncbi.nlm.nih.gov]
Lactose Intolerance
  • Respondents with self-perceived lactose intolerance had significantly lower (P 0.05) average daily calcium intakes from dairy foods than did those without self-perceived lactose intolerance.[ncbi.nlm.nih.gov]
  • There is no treatment for lactose intolerance, but symptoms can be managed through diet changes. What is lactose intolerance? Lactose intolerance is when your body can't break down or digest lactose.[hopkinsmedicine.org]
  • PURPOSE: To assess the maximum tolerable dose of lactose and interventions for reducing symptoms of lactose intolerance among persons with lactose intolerance and malabsorption.[ncbi.nlm.nih.gov]
  • Since dairy nutrients address important health concerns, the amelioration of lactose intolerance is an investment in health. Lactose intolerance is common, is easy to treat, and can be managed.[ncbi.nlm.nih.gov]
  • RESULTS: A total of 21 out of 51 patients (41.1%) were self-perceived to be lactose intolerant, 24/51 (47%) had a positive HBT, and 14/51 (27.4%) presented with symptoms of lactose intolerance during HBT.[ncbi.nlm.nih.gov]
Diarrhea
  • BACKGROUND: Lactose intolerance is a form of lactose maldigestion where individuals experience symptoms such as diarrhea, abdominal cramping, flatulence, vomiting and bowel sounds following lactose consumption.[ncbi.nlm.nih.gov]
  • Diarrhea and borborygmi were mostly associated with LM.[ncbi.nlm.nih.gov]
  • The control groups were 126 cases of infants with diarrhea randomly collected from our hospital at the same period, which their rotavirus detection was negative.[ncbi.nlm.nih.gov]
  • Individuals with intolerance to lactose cannot drink regular cow's milk without developing diarrhea, gas, and often abdominal pain.[medicinenet.com]
  • The most frequent symptoms of LI in junior high school (JHS) group were abdominal pain (64.1%), abdominal distention (22.6%), nausea (15.1%), flatulence (5.7%), and diarrhea (1.9%), mostly within one hour of lactose ingestion.[ncbi.nlm.nih.gov]
Abdominal Pain
  • A reduction in abdominal pain was also demonstrated in the study results. Fifty percent of RP-G28 subjects with abdominal pain at baseline reported no abdominal pain at the end of treatment and 30 days post treatment (p   0.0190).[ncbi.nlm.nih.gov]
  • LI was found in 81% of RAP children with abdominal pain most frequently, followed by nausea, bloating, diarrhea, borborygmi, and flatulence. Symp-tom onset occurred 30 minutes after lactose ingestion, especially nausea, bloating, and abdominal pain.[ncbi.nlm.nih.gov]
  • Symptoms of abdominal pain, nausea, borborygmi, flatulence, diarrhea and others were noted for 24 hours and blood glucose was estimated at 0 hour and 30 minutes after 50 gm oral lactose load to healthy volunteers.[ncbi.nlm.nih.gov]
  • Symptoms of lactose intolerance include abdominal pain, bloating, flatulence and diarrhea with a considerable intraindividual and interindividual variability in the severity.[ncbi.nlm.nih.gov]
  • Common symptoms include abdominal pain and bloating, excessive flatus, and watery stool following the ingestion of foods containing lactose.[ncbi.nlm.nih.gov]
Abdominal Cramps
  • BACKGROUND: Lactose intolerance is a form of lactose maldigestion where individuals experience symptoms such as diarrhea, abdominal cramping, flatulence, vomiting and bowel sounds following lactose consumption.[ncbi.nlm.nih.gov]
  • cramps and diarrhea after ingesting an amount of lactose equivalent to that in one quart of milk; 14 reported similar symptoms after one or two glasses of milk; all had consumed milk as infants without having such symptoms.[doi.org]
  • Symptoms are abdominal cramps, flatulence and watery, acid stools, and decrease the quality of life but lactose intolerance is not associated with "true disease".[ncbi.nlm.nih.gov]
  • Nineteen of 20 healthy Oriental adults living in the United States developed abdominal cramps and diarrhea after ingesting an amount of lactose equivalent to that in one quart of milk; 14 reported similar symptoms after one or two glasses of milk; all[ncbi.nlm.nih.gov]
  • Outcomes were area under the breath H2 curve (AUC H2) and self-reported symptom severity (visual analog scales: flatulence/gas, audible bowel sounds, abdominal cramping, diarrhea).[ncbi.nlm.nih.gov]
Borborygmi
  • Diarrhea and borborygmi were mostly associated with LM.[ncbi.nlm.nih.gov]
  • Lactose intolerance related to primary or secondary lactase deficiency is characterized by abdominal pain and distension, borborygmi, flatus, and diarrhea induced by lactose in dairy products.[ncbi.nlm.nih.gov]
  • LI was found in 81% of RAP children with abdominal pain most frequently, followed by nausea, bloating, diarrhea, borborygmi, and flatulence. Symp-tom onset occurred 30 minutes after lactose ingestion, especially nausea, bloating, and abdominal pain.[ncbi.nlm.nih.gov]
  • Borborygmi may also be experienced. On physical examination, the abdomen may be tender. One may feel the bloating of the abdomen. Auscultation may reveal borborygmi sounds.[symptoma.com]
  • The result is an unfortunate combination of diarrhea, cramps, and the sound of gurgling or rumbling in the belly, also known as borborygmi.[rd.com]

Workup

Diagnosis of lactose intolerance can be done with a complete history and by certain dietary manipulations. There are few laboratory tests which aid in the diagnosis.

One of them is lactose tolerance test. In this test, the fasting blood glucose levels are measured. Then 50g lactose is given [12]. Serial blood glucose levels are measured as 0, 60, 120 minutes. If the levels increase less than 20 mg/dL above the fasting level then the test is positive. False negative results occur in cases with diabetes, abnormal gastrointestinal emptying etc [13].

The other is milk tolerance test. 500 ml of milk is given and if the glucose levels rise less than 9 mg/dL, then it indicates lactose intolerance [14].

Breath hydrogen test is more specific as compared to lactose tolerance test [6]. Patients are given lactose and then the expired air is assessed for hydrogen gas concentrations. Rise in the concentration more than 20 ppm after lactose administration indicates lactose intolerance due to lactase deficiency [12]. Sleep, exercise, smoking, aspirin use can cause false-positive results.

Dietary manipulations involve diagnosing lactose intolerance by reducing intake of lactose-containing foods to check disappearance of the symptoms. The symptoms reappear as soon as lactose-containing foods are re-started [15] [16].

Small bowel biopsy is very rarely performed though it is a confirmatory test. Biopsy samples of the small intestine are tested for lactase activity.

One can use various imaging techniques in cases where secondary causes of lactose intolerance are to be detected.

Treatment

Most individuals can manage the symptoms by simple dietary modifications. Some can tolerate cheese better than milk, so instead of milk one can consume milk products like cheese or yogurt for daily calcium intake. Some who can tolerate small amounts of lactose may need to limit lactose intake or change the form in which they consume it. For example, some individuals can tolerate milk when combined with other meals like cereals, or cheese spread over other foods. Some individuals may need to stop lactose completely.

One must also make note and avoid all other non-dairy products and grocery items which contain lactose like bread, margarine, salad dressing, some snacks or candies, certain medications etc.

A dietary plan will help control the symptoms and not compensate on the nutrients. In cases of secondary lactose intolerance, one must treat the underlying cause to control lactose intolerance.

Lactose-free or lactose-reduced milk or milk products which are treated with lactase enzyme are recommended to meet the nutritional needs. Lactase tablets which help digest lactose from the food can be consumed along with lactose-containing foods.

Non-milk products like fish, dark green leafy vegetables are high in calcium content. Foods fortified with calcium and vitamin D can meet the nutritional needs of the body.

Prognosis

Lactose intolerance has a very good prognosis with appropriate dietary care. Osteopenia can be observed as a complication to lactose intolerance [9] [10].

Etiology

Lactose intolerance is said to occur when an individual suffers from lactase enzyme deficiency and the resulting malabsorption. Lactose is not well digested and undigested lactose may pass through the intestines producing gastrointestinal symptoms.

Lactase deficiency can cause three types of lactose intolerances as follows:

  1. Primary lactose intolerance: This is one of the commonest causes of lactose intolerance where the production of lactase reduces after about 2 years of age or even later. They could digest lactose initially but cannot do so now due to lactase deficiency.
  2. Secondary lactose intolerance: This occurs when the mucosa of the small intestine is damaged due to any infection or acute illness. It can be caused due to diseases like acute gastroenteritis, giardiasis, ascariasis, gastrinoma, chemotherapy etc. This can happen at any point in life.
  3. Congenital lactose intolerance: Is an autosomal-recessive trait and hence is very rare [2] [3]. There is deficient lactase enzyme production right from birth.

Epidemiology

The incidence of lactose intolerance differs depending on the race. The incidence among southern Europeans is about 25 to 30% while that among the Native Americans and Asian Americans is about 75 to 90% [4]. The prevalence of lactose intolerance is highest among Asians, South Americans and Africans.

Commonly affected age group is from 20 to 40 years old [2] [5]. Its prevalence among both the genders is equal. During pregnancy, some of the women tend to recover their ability to digest lactose.

Sex distribution
Age distribution

Pathophysiology

Lactose is digested and broken down into glucose and galactose by the enzyme lactase produced by the intestinal villi. In cases where lactase is deficient, this process of hydrolysis is averted. The unabsorbed lactase triggers increased secretion of fluid and electrolytes in the intestine till the osmotic balance is reached.

The intestine itself cannot maintain a high electrochemical gradient between the contents and the blood; hence there is fluid influx which is about three times the osmolality of lactose [6] [7].

This osmosis increases the rate of the intestinal movement causing indigestion. The free lactose is fermented in the bowel by the colonic bacteria into short-chain fatty acids and releases hydrogen gas [8]. The increased bowel movements, the excess fluid and gases lead to the gastrointestinal symptoms like bloating, flatulence, diarrhea, abdominal discomfort, etc.

Prevention

One cannot prevent lactose intolerance but one can definitely control the discomfort and reduce the intensity of the symptoms one experiences due to intake of lactose.

Individuals must read labels carefully on all products. One must not only look out for words like milk or lactose but also for whey, curds, milk products, milk powder etc.

Avoiding intake of milk in the direct form can help reduce symptoms. Instead try consuming milk products or blend it with other food products.

Summary

Lactose is a disaccharide, a sugar found in milk as well as milk products. The name comes from ‘lac’ or ‘lactis’, the latin word for milk. The intestinal villi produce an enzyme called lactase (β-D-galactosidase). This enzyme breaks down lactose into simple, monosaccharide sugars - glucose and galactose. These are then absorbed easily into the blood.

Lactose intolerance implies an inability to digest lactose and break it into glucose and galactose due to deficiency or lack of lactase called as hypolactasia [1].

Patient Information

Lactose is a type of sugar found in milk and milk products. Deficiency of an enzyme lactase leads to lactose intolerance. Lactase breaks down lactose into simpler sugars called glucose and galactose. When lactose doesn’t get digested it leads to symptoms like abdominal bloating, diarrhoea, pain and flatulence.

Diagnosis is made by taking a detailed history and dietary manipulations. Medical tests like lactose tolerance test, breath hydrogen test, biopsy etc. help to diagnose it. One must rule out other causes of digestive disturbances like milk allergy, inflammatory bowel disease etc. as the symptoms can be misleading.

Individuals with lactose intolerance have a variable amount of lactose they can safely tolerate. Many individuals can manage the symptoms by dietary modifications. Some may need to restrict lactose-containing foods like milk and milk products while others may have to stop it completely. One must read the labels of all products to check any sources of lactose in it. A dietary plan can help one to meet the nutritional needs of the body. One can consume calcium and vitamin D supplements or fortified foods to compensate for the lack of milk in the diet.

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Last updated: 2018-06-22 04:26