Diet Tips:What is lactose intolerance?

By Lyndal McNamara (APD)

As a dietitian, I often see patients who have just been diagnosed with lactose intolerance and understandably assume that this means they need to avoid all dairy products. You will be relieved to know that this is certainly not the case! In fact, most dairy products can still be enjoyed on a low lactose diet. But first, what exactly is lactose and what does a diagnosis of lactose intolerance really mean in terms of diet?  

What is lactose and what is lactose intolerance?

Lactose is a type of sugar found most commonly in milk and other dairy products. When foods/drinks containing lactose are consumed, the body needs the help of an enzyme named lactaseto break down the lactose sugar into smaller pieces for digestion and absorption (see picture below). Individuals who have lactose intolerance make less lactase enzyme, so may find it difficult to digest lactose properly when they consume a large amount of a lactose-containing food/drink. This can ultimately result in unpleasant symptoms such as bloating, wind, stomach cramps and diarrhoea.

What is the difference between lactose intolerance and an allergy to dairy?

Lactose intolerance should not be confused with a dairy allergy. A true food allergy is an adverse reaction to a food that involves the body’s immune system and can result in severe symptoms that can even be life threatening. Someone with a dairy allergy may experience severe symptoms even if they consume minute quantities of a dairy product; it is therefore usually essential that they strictly avoid all dairy. Lactose intolerance is different in that consumption of small to even moderate amounts of lactose may not actually trigger any symptoms. Despite the symptoms of lactose intolerance being unpleasant, exposure to too much lactose will not result in life threatening symptoms. Strict avoidance of lactose is therefore unnecessary. 

How much lactose can I have before experiencing symptoms?

This will vary between individuals, however research suggests that most people with lactose intolerance can tolerate 12-15g of lactose per day (equivalent to up to 250ml of regular milk) and possibly even more if lactose consumption is spread throughout the day rather than in a single sitting. (1-3)

Is there anything I can take/do to improve my tolerance to lactose?

Lactase enzyme products (tablets or drops) are available at most pharmacies and may assist with lactose digestion when taken with a lactose containing food. Consuming lactose containing foods together with other foods may also improve tolerance.(3)

How much lactose do dairy products actually contain?

As you can see from the table below, this is very variable! Whilst regular milk is high in lactose, many common cheeses such as cheddar, feta and even soft cheeses like brie and camembert contain virtually no lactose in a typical serve. Whilst yoghurt is listed as a high lactose food, there are many varieties available that are low lactose or even lactose free that are usually well tolerated. Try yoghurts that have added live bacterial cultures, as these are usually easier to digest. Lactose free varieties of many dairy products including cow’s milk, cream, sour cream and cream cheese are also now readily available. These products are identical to the regular variety, they simply have some lactase enzyme added to them, and so the lactose has already been digested for you!

Lactose content of common dairy foods

Dairy product	Lactose content /serve	Serving size	Lactose classification/serve
Full cream milk	15.75g	250ml	High
Low-fat milk	15.25g	250ml	High
Skim milk	12.5g	250ml	High
Natural Yoghurt	8.5g*	170g	High
Regular flavoured yoghurt	5.8g*	170g	High
Thickened Cream	3.75g	125ml	Moderate
Sour cream	3.13g	125ml	Moderate
Cream cheese	2.0g	80g	Moderate
Ricotta Cheese	1.6g	80g	Moderate
Cottage cheese	0.7g	36g	Low
Feta Cheese	0.13g	125g	Low
Cheddar (tasty) Cheese	0.04g	40g or 2 slices	Low
Camembert Cheese	0.04g	40g	Low
Brie Cheese	0.04g	40g	Low

 

*The lactose content of yoghurt varies significantly between brands and this value reflects the average lactose content only.

Data source: NUTTAB 2010 database

Will I miss out on any essential nutrients if I follow a lactose free diet?

Many dairy foods containing lactose are important sources of calcium in the diet, so if you avoid dairy products for any reason, it is important that they are replaced with suitable calcium rich alternatives. The range of lactose free dairy products available on the market mean that you can consume a low lactose, calcium rich diet very easily. Choose lactose free milk, probiotic yoghurts or lactose free yoghurts and choose naturally low lactose cheeses from the list above. If you do this you will still get enough calcium in your diet. Alternatively, if you choose non-dairy, lactose free milks including those made from soy, rice, nuts such as almonds and even coconut, it is important to ensure that you buy a brand that contains added calcium, as these products do not naturally contain much calcium. Ideally look for a variety that has 200-300mg of calcium per 250ml serve. Remember to always speak to your dietitian before making major changes to your usual diet to ensure you will not be missing out on any important nutrients!

References:

1.            Savaiano DA, Boushey CJ, McCabe GP. Lactose intolerance symptoms assessed by meta-analysis: a grain of truth that leads to exaggeration. The Journal of nutrition. 2006;136(4):1107-13.

2.            Suarez FL, Savaiano D, Arbisi P, Levitt MD. Tolerance to the daily ingestion of two cups of milk by individuals claiming lactose intolerance. The American journal of clinical nutrition. 1997;65(5):1502-6.

3.            Shaukat A, Levitt MD, Taylor BC, MacDonald R, Shamliyan TA, Kane RL, et al. Systematic Review: Effective Management Strategies for Lactose Intolerance. Annals of Internal Medicine. 2010;152(12):797-803.

Diet Tips:Rice Milks Revisited: Moving from red to green rating in app

By Dr Jane Muir 

Everyone was very disappointed when our rating for rice milk was red = high FODMAP!

We have had many requests to conduct further testing of rice milks from different countries.  Our team has just completed testing rice milks from Australia, United Kingdom and the United States.

Remember that the analysis of all FODMAPs in food is a complex and time-consuming process undertaken by the laboratory team here at Monash.  Some foods (particularly processed foods) present technical challenges.  Rice milk is one of these challenging foods. 

Currently, rice milk has been given a red rating in the app.  This was due to the presence of very high level of oligosaccharides (Oligos) that our team detected in the rice milk samples. As we discussed in our last rice milk blog – this high level of Oligos are due to the enzymatic breakdown of the rice flour starch to release glucose (this is how rice milk is made).  As you can see from the diagram below, rice starch is a large and complex carbohydrate - made up of chains of glucose (these can be very long - thousands of glucose units long). The enzymes used to make rice milk sometimes fail to completely break down the rice starch and as a result some small oligos are left behind.  The key point here is that these types of starch-derived oligos are digestible, unlike the Oligos- fructans and GOS. So these are not really FODMAPs!

Our laboratory team has discovered that these starch-derived oligos get mixed up with the FODMAP - GOS-oligos during the laboratory analysis. This means it has been difficult to know how much of these oligos are starch-derived and therefore well tolerated, and how much is GOS, a FODMAP, poorly tolerated. The team has recently established a new technique to answer this question. As a result of their hard work, they have discovered that there is little GOS in rice milk and indeed these Oligos are probably starch-derived and therefore well tolerated. All rice milks have been re-tested using this new method.

We have now reviewed the rating for rice milk and will be modifying this accordingly.  We have given a safe (low level greenrating) for 200 ml of rice milk per sitting.  The results for the Australian, UK and US will be in the app very soon. We apologize for any confusion this may have caused - but this is science in action! and part of the ongoing research and refinement of the Monash University Low FODMAP diet.

Be careful:  There are still some fructans present in some rice milks and therefore we do not recommend very high quantities of rice milk in one sitting.

So will this problem of starch-derived Oligos affect other food ratings in the app?  We have reviewed other foods in the app and we have not found any other foods which have been affected by this technical issue.