Lactose Intolerance

Many people with gastrointestinal symptoms such as bloating, discomfort and diarrhoea believe that they have lactose intolerance and avoid or limit their intake of dairy foods and may not be consuming enough calcium. Most people with confirmed lactose intolerance can comfortably eat some dairy food.

WHAT IS LACTOSE?

Lactose is the naturally occurring sugar found in dairy products such as milk and ice cream.

WHAT IS LACTOSE INTOLERANCE?

During digestion lactose is broken down in the small intestine. An enzyme called lactase splits the lactose into two simple sugars - glucose and galactose. Lactose malabsorption occurs when there is insufficient lactase enzyme to break down all the lactose. This results in some lactose passing undigested into the large bowel where bacteria break it down to produce lactic acid, carbon dioxide and hydrogen gas. Many people with lactose malabsorption do not experience gastrointestinal symptoms. If symptoms such as bloating, cramps, wind and diarrhoea are experienced by people with lactose malabsorption it is which is then called lactose intolerance. Unfortunately the symptoms of lactose intolerance may actually be due to other conditions such as irritable bowel syndrome and so it can be misdiagnosed.

HOW COMMON IS LACTOSE INTOLERANCE AND WHO IS AFFECTED?

We do not have accurate figures as much of the data available is from people who believe they have lactose intolerance but it has not been medically confirmed. The incidence of lactose intolerance in Australians is thought to be around 10% but it is reportedly higher in America, Very few babies are born with lactose intolerance. This genetic condition is rare and is usually noticed within the first few weeks of life as the infants cannot tolerate breast milk which contains lactose and therefore require a special lactose free formula.

Many people have a reduction in lactase levels after childhood and this is the cause of most lactose intolerance. This is more common in certain ethnic groups such as Middle Eastern, Asian, Southern European, African and indigenous Australians. A temporary form of lactose intolerance can also occur following an acute episode of gastroenteritis, or inflammation of the mucosal lining of the intestines such as occurs in Crohn’s disease. This is because the cells that produce the lactase enzyme are damaged. This form of lactose intolerance may improve once the triggering illness has been treated.

DIAGNOSING LACTOSE INTOLERANCE

It is important that lactose intolerance is correctly diagnosed by a medical professional to ensure that dairy foods are not avoided unnecessarily. This is usually done by measuring the levels of hydrogen gas in the breath after consuming a drink high in pure lactose on an empty stomach. Remember you can be a lactose malabsorber without having the symptoms of lactose intolerance.

HOW MUCH LACTOSE IS IN FOODS?

This table shows the lactose content of some common dairy products:

Food Serve Size Lactose Calcium
Milk, regular 250ml 12g 290mg
Yogurt, regular, natural 200g 8g 340mg
Cheese, cheddar 40g 0g 300mg
Cream cheese 20g 0.6g 56mg
Ice cream 50g 3g 45mg
Chocolate (milk) 50g 4.6g 125mg
Soy beverage (fortified) 250ml 0g 290mg
Source: NUTTAB 2006

TIPS ON MANAGING LACTOSE INTOLERANCE

Individuals have different levels of lactase insufficiency and can tolerate varying amounts of lactose. Most people will be able to manage small amounts of dairy foods, spread across the day. Avoiding dairy altogether can result in an inadequate calcium intake which increases the risk of osteoporosis - a disease in which bones become fragile and break easily. Including low fat dairy foods in the diet is important as they are nutrient rich and one of the richest sources of calcium.

Try to eat low lactose foods such as hard cheeses which have almost no lactose, or yogurts where the live bacteria have already reduced the lactose levels and help to digest the lactose. Another tactic is to consume dairy foods, such as milk, with a meal. This dilutes the lactose and the slower emptying of the stomach improves digestion and tolerance. Some people with lactose intolerance completely eliminate dairy foods from their diets. However, including dairy in small amounts with other foods helps your body to better tolerate lactose as the enzymes of the bacteria in the colon become more efficient in the process of large bowel fermentation.

If you decide to use soy beverages instead of cow’s milk, ensure they are calcium fortified (calcium is added to the product to levels similar to cow’s milk). Lactose free yogurts and milks and soy yogurts are also available for those people who wish to avoid lactose completely. Cow’s milk based products labeled as “lactose free” will have lactase which is the enzyme which breaks down lactose added early in processing. A “lactose free” product will contain no detectable levels of lactose.

HEALTHY DIET TIPS LACTOSE INTOLERANCE

Aim to include three dairy serves each day

Mild lactose intolerance Moderate lactose intolerance

Include matured cheeses as they are low in lactose e.g. cheddar, parmesan, camembert, feta

Regular fat milk is usually tolerated better than reduced fat or skim varieties as the fat slows release from the stomach and reduced fat milks are higher in lactose

Include yogurt with a live bacterial culture to help break down the lactose

Try a small glass of milk with food as this is better tolerated and will help you maintain your remaining lactase levels and also bacteria in your bowel that can break down lactose

Include lactose free milks and yogurts either soy, oat, rice or nut with added calcium or cow’s milk with added lactase enzyme both are lactose free

Include matured cheeses as they are low in lactose e.g. cheddar, parmesan, camembert, feta

Small quantities or milk (20-30 ml) are usually well tolerated

Consider trying lactase enzyme supplements when eating out or having foods high in lactose

Test yourself occasionally with a small glass of milk with food to see if you still need to keep your lactose level low

Include lactose free milks and yogurts either soy, oat, rice or nut with added calcium or cow’s milk with added lactase enzyme both are lactose free

A small number of people have severe lactose intolerance and may need to limit even foods with low levels of lactose. If you believe that you have severe lactose intolerance you need to have this confirmed by your doctor and to check that you do not have an intolerance or allergy to cow’s milk protein instead. If you have cow’s milk intolerance or allergy you will need to obtain calcium from soy products with added calcium, some seeds and nuts, fish with edible bones like sardines and may also require a calcium supplement.

This fact sheet contains general information and is not intended as a substitute for medical advice. Please consult your healthcare professional for specific advice for your personal situation.

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REFERENCES

NIH State-of-the-Science Conference Statement on Lactose Intolerance and Health NIH Consensus and State-of-the-Science Statements. Volume 27, Number 2 February 22–24, 2010 www.consensus.nih.gov/2010/lactose.htm

Järvelä I, Torniainen S, Kolho KL. Molecular genetics of human lactase deficiencies. Ann Med. 2009;41(8):568-75. Barrett JS, Irving PM, Shepherd SJ, Muir JG, Gibson PR Comparison of the prevalence of fructose and lactose malabsorption across chronic intestinal disorders. Aliment Pharmacol Ther. 2009 Jul 1;30(2):165-74. Epub 2009 Apr 15.

Aasma Shaukat, MD, MPH; Michael D. Levitt, MD; Brent C. Taylor, PhD, MPH; Roderick MacDonald, MS; Tatyana A. Shamliyan, MD; Robert L. Kane, MD; and Timothy J. Wilt, MD, MPH Systematic Review: Effective Management Strategies for Lactose Intolerance Ann Intern Med. 2010;152:797-803.

Thomas, B. Manual of Dietetic practice. 2nd Ed. Blackwell Science Ltd University Press, Cambridge, 1999. Savaiano, D. Nutrition Reviews 2003; 61(6):221-3

Australian Dietary Guidelines and Australian Guide to Healthy Eating (last updated 2 April 2009) www.health.gov.au/internet/healthyactive/publishing.nsf/Content/eating

Australian Government Consumer Resources www.health.gov.au/internet/main/publishing.nsf/Content/health-pubhlth-strateg-food-resources.htm#consumers

Australian Government process updating guidelines www.nhmrc.gov.au/your_health/healthy/nutrition/index.htm#blog NHMRC, The Dietary Guidelines for Australian Adults. 2003: Commonwealth Department of Health and Ageing