The small intestine is a hollow tube that runs from the stomach to the large intestine (colon).

People with lactose intolerance are unable to fully digest the sugar (lactose) in milk. As a result, they have diarrhea, gas and bloating after eating or drinking dairy products. The condition, which is also called lactose malabsorption, is usually harmless, but its symptoms can be uncomfortable.

Too little of an enzyme produced in your small intestine (lactase) is usually responsible for lactose intolerance. You can have low levels of lactase and still be able to digest milk products. But if your levels are too low you become lactose intolerant, leading to symptoms after you eat or drink dairy.

Most people with lactose intolerance can manage the condition without having to give up all dairy foods.

If not managed properly, lactose intolerance may cause severe digestive problems. These symptoms may appear as quickly as 30–60 minutes after eating.

The most common symptoms are:

• Bloating
• Abdominal cramps
• gas
• Diarrhea
• Nausea

Some people also experience an urgent need to go to the toilet, Vomiting, lower belly pain, and Constipation.

Diarrhea occurs due to undigested lactose in your small intestine, which causes water to move into your digestive tract.

Once it reaches your colon, the lactose is fermented by the bacteria in your gut, forming short-chain fatty acids (SCFAs) and gas. This causes Bloating, gas, and pain.

The severity of symptoms varies based on how much lactose you can tolerate and how much you’ve eaten.

Fortunately, these symptoms last only briefly. You’re also typically not affected unless you consume large amounts of lactose or have another condition that’s worsened by the digestive irritation caused by lactose intolerance.

Lactose intolerance occurs when your small intestine doesn't produce enough of an enzyme (lactase) to digest milk sugar (lactose).

Normally, lactase turns milk sugar into two simple sugars — glucose and galactose — which are absorbed into the bloodstream through the intestinal lining.

If you're lactase deficient, lactose in your food moves into the colon instead of being processed and absorbed. In the colon, normal bacteria interact with undigested lactose, causing the signs and symptoms of lactose intolerance.

There are three types of lactose intolerance. Different factors cause the lactase deficiency underlying each type.

Primary lactose intolerance

People who develop primary lactose intolerance — the most common type — start life producing enough lactase. Infants, who get all their nutrition from milk, need lactase.

As children replace milk with other foods, the amount of lactase they produce normally drops, but usually remains high enough to digest the amount of dairy in a typical adult diet. In primary lactose intolerance, lactase production falls off sharply by adulthood, making milk products difficult to digest.

Secondary lactose intolerance

This form of lactose intolerance occurs when your small intestine decreases lactase production after an illness, injury or surgery involving your small intestine. Diseases associated with secondary lactose intolerance include intestinal infection, celiac disease, bacterial overgrowth and Crohn's disease.

Treatment of the underlying disorder might restore lactase levels and improve signs and symptoms, though it can take time.

Congenital or developmental lactose intolerance

It's possible, but rare, for babies to be born with lactose intolerance caused by a lack of lactase. This disorder is passed from generation to generation in a pattern of inheritance called autosomal recessive, meaning that both the mother and the father must pass on the same gene variant for a child to be affected. Premature infants can also have lactose intolerance because of an insufficient lactase level.

In people with lactose intolerance caused by an underlying condition, treating the condition might restore the body's ability to digest lactose, although that process can take months. For other causes, you might avoid the discomfort of lactose intolerance by following a low-lactose diet.

To lower the amount of lactose in your diet:

• Limit milk and other dairy products
• Include small servings of dairy products in your regular meals
• Eat and drink lactose-reduced ice cream and milk
• Add a liquid or powder lactase enzyme to milk to break down the lactose

Factors that can make you or your child more prone to lactose intolerance include:

• Increasing age. Lactose intolerance usually appears in adulthood. The condition is uncommon in babies and young children.
• Ethnicity. Lactose intolerance is most common in people of African, Asian, Hispanic and American Indian descent.
• Premature birth. Infants born prematurely might have reduced levels of lactase because the small intestine doesn't develop lactase-producing cells until late in the third trimester.
• Diseases affecting the small intestine. Small intestine problems that can cause lactose intolerance include bacterial overgrowth, celiac disease and Crohn's disease.
• Certain cancer treatments. If you've had radiation therapy for cancer in your stomach or you have intestinal complications from chemotherapy, your risk of developing lactose intolerance increases.

Lactose intolerance (lactase deficiency) is the lack of digestive enzymes required for digesting the lactose sugar found in milk and dairy products. The problem occurs as a genetic predisposition, though the condition is harmless. This can cause severe bloating, indigestion, vomiting, diarrhea, etc., on the consumption of dairy products.

• The best method to treat this condition is avoidance of dairy products and shift to non-dairy alternatives like soymilk etc.
• The second alternative is to choose among assorted dairy products like hard cheese etc., with low lactose.
• Consuming dairy products along with meals can reduce the symptoms.
• In severe conditions, lactase enzyme tablets or drops can be used. They contain lactase enzymes which can help in the consumption of dairy products.
• Probiotics with live culture can be taken to improve the dairy digesting ability.

Conditions
Osteopenia,Osteoporosis,Malnutrition
Drugs
Avoiding dairy food,Lactase enzyme supplements
Symptoms
Indigestion,Diarrhea,Dehydration