Milk and Lactose Intolerance

Milk is an excellent source of vitamins and minerals, particularly calcium. It has long been recognised for its important role in bone health. Nutritionists recommend that milk and other dairy products should be consumed daily as part of a balanced diet. There are fallacies in the general community about the health benefits or otherwise of milk. Changing your milk intake on the basis of these fallacies can lead to the unnecessary restriction of this highly nutritious drink

Nutrients
Milk and milk products contain a good balance of protein, fat and carbohydrate (lactose). Milk products are also a very important source of essential nutrients including:
· Calcium - there is 1mg of calcium in 1ml of full fat milk
· Riboflavin
· Phosphorous
· Vitamins A, D, B12
· Pantothenic acid.

Milk products also contain 'high quality proteins' which are highly suited to human needs. Apart from being important nutrients themselves, milk proteins increase the value of poorer quality cereal and vegetable proteins in the diet by providing the amino acids these proteins lack.

Modified milks explained
There are many different types of modified milks on the market. Some of the more common include:
Full cream - full cream milk contains around four per cent fat. This is a rich source of vitamins A and D. Pre-school children should be given full cream milk, rather than reduced fat varieties.
Reduced fat - on average, you can expect around half as much fat in reduced fat milk as full cream. However, vitamin A and D content is also reduced.
Skim - this can taste quite watery, since all the fat is removed. Skim milk doesn't contain any vitamin A or D.
Calcium enriched - generally, those milks that are enriched with extra calcium (by adding skim milk powder) are also fat reduced. A 250ml glass of milk contains around 420mg to 450mg of calcium. This type of milk also contains more lactose than full cream milk.
Unpasteurised - the pasteurisation process kills bacteria by heating the milk to a temperature intolerable to micro-organisms. Some vitamins are lost in this process, such as vitamin C. However, unpasteurised milk is a health hazard because of the dangers of bacterial diseases.
Flavoured - these milks can either be full cream or reduced fat, depending on the brand. However, most varieties contain artificial additives and a lot of sugar.
UHT (ultra-high temperature-treated) milk - allows milk to be stored for long periods of time. There may be a loss of some vitamins during processing but there is little physical or chemical change in the milk fat. It may cause some reduction in the amount of unsaturated fats in milk triglycerides (fats). UHT treatment causes milk proteins to 'denature'. This may increase the digestibility of proteins and increase the nutritional value of milk. There is more calcium and potassium retained in UHT milk than pasteurised milk.
Ultrafiltered - changes the mineral and vitamin composition of whole milk. Some vitamins and minerals are partially lost - for example, 35 per cent of vitamin B6 and 15 per cent of riboflavin are lost. Fat, protein, vitamin B12 and folic acid are fully retained by this process.

Milk and health
Australians tend to severely restrict or cut out dairy foods when they try to lose weight. The heavy promotion of low fat milks may be contributing to the false belief that dairy foods are inherently fattening. Dairy foods contain saturated fats, which have been associated with increased blood cholesterol levels. This isn't a threat to good health if these products are consumed in moderation as part of an otherwise nutritious and varied diet. Switching to low fat milk will increase the nutrient density and decrease the energy density in the diet.

Osteoporosis
Australians receive the bulk of their calcium from dairy foods. If milk is removed from the daily diet it can lead to an inadequate intake of calcium. This is of particular concern for women, who have high calcium needs. Calcium deficiency may lead to disorders like osteoporosis (a degenerative disease characterised by bone loss).
A report published in the journal Pediatrics (March 2005), reviewed 37 studies examining the impact of calcium consumption on bone strength in children older than seven and found that 27 did not support drinking more milk to boost calcium intake and that children who drink more milk do not necessarily develop healthier bones. Several studies, which examined such factors as bone density and rate of fractures, concluded that exercise may be more important than increased calcium consumption in developing strong bones.With the rising prevalence of obesity in children, there is concern that promoting the consumption of dairy products may contribute to excess calories (especially of full fat products are consumed). For example,in the US, dairy products currently provide 18 per cent of the total energy and 25 per cent of the total fat intake in the diets of American children. So promoting low fat low sugar sources of calcium seems desirable.
The researchers highlighted that consuming more milk/milk products was not necessarily the best way to provide the minimal calcium intake of at least 400 milligrams per day (recommended between 800-1300mg per day). Other ways to obtain the absorbable calcium found in one cup of cow's milk include:
- a cup of fortified orange juice
- a cup of cooked kale (a type of cabbage)
- two packages of instant oats
- two-thirds of a cup of tofu
- one to two thirds of a cup of broccoli
Some of these non milk sources of calcium contain phytoestrogens which have been linked to stronger bones. Asian populations have high intakes of phytoestrogens which may be contributing to the low rates of osteoporosis.

Colon Cancer
Recent studies have also found that people who eat a lot of dairy products or dairy product nutrients like calcium, have a reduced risk of developing colon cancer.

Blood pressure
Research in the U.S. found high intake of fruits and vegetables combined with low-fat dairy decreased blood pressure more than fruits and vegetables alone.

Heart Disease
A New Zealand scientist believes a protein found in milk could be responsible for thousands of cases of heart disease world-wide. Specifically, beta casein A1, found in milk from Westernised countries has been suggested to increase risk for heart disease in people at already high risk. In contrast, beta casein A2 is thought to be harmless. Casein A1 is thought to break up more readily in the blood stream than A2 and cause damage to the arteries. A2 is found milk from Indian and African cattle. This hypothesis is yet to be proven and is very controversial. Studies are underway in Australia to prove whether these proteins affect blood vessel health in people with known cardiovascular risk factors. Further evidence is needed before so called "healthy" forms of milk are proactively marketed to the public as a way of helping to reduce the risk of heart disease.

Type 1 diabetes (insulin dependent)
There is emerging evidence that the protein casein A1 found in milk produced by certain cows may be involved in the development of type 1 diabetes in children. More research is needed.

Type 2 diabetes
A ten-year study of 3,000 overweight adults aged 18 to 30 concluded that consuming milk and other milk products instead of refined sugars and carbohydrates, may protect overweight young adults from developing type 2 diabetes. The researchers theorise that milk's nutrients, such as calcium, potassium and magnesium, might protect against diabetes. Milk products also tend to be quite satisfying or satiating which may prevent overeating. The study also found that study participants with diets high in dairy foods also consumed more grains, fruits and vegetables, and fewer sugar sweetened soft drinks.

Milk avoiders and Flavoured milk
A study published in the Am J Clin Nutr 2002; 76: 675-80 by Black et al reported that children who avoid milk tended to be fatter than children who drank milk. This may be because milk is being replaced by high energy drinks such as fruit juice or soft drinks. Another study published in the Journal of American Dietetic Association in 2002 found that American children aged 5 to 17 years who drink flavored milk have higher total milk intake, lower soft drink and fruit drink intake, but similar fruit juice intake. Almost 4,000 children were studied. Flavored milk did not add to the total sugar or fat content of the diet. As children move into adolescence, at the time they need the most calcium, they tend to decrease milk consumption and greatly increase the intake of soft drinks. For some children in this study, sugar intake from soft drinks represented a quarter or third of daily calorie requirements; at such high intakes it becomes very difficult to obtain required nutrients without gaining a lot of weight. Milk is clearly a nutrient-dense food that should be consumed in preference to beverages more popular with children - flavored milks might be more acceptable to children.

Milk and tooth decay
Milk and milk products are thought to have a protective effect against tooth decay.
Eating cheese and other dairy products:
· Reduces oral acidity (which causes decay)
· Stimulates saliva flow
· Decreases plaque formation
· Decreases the incidence of dental caries.

Milk and mucous
It is commonly believed that nasal stuffiness is related, in part, to how much milk you regularly drink. Many people who suffer from frequent colds or recurrent sinus infections, for example, have at least heard of cutting out milk as a possible remedy. However, there is no scientific basis to this theory. Milk, whether it is cow or goat, modified or otherwise, doesn't encourage extra mucous production in the human body. Curiously, this belief seems localised to Australia.

Cow's milk versus goat's milk
Some people switch to goat's milk because of perceived sensitivities to cow's milk. If a person has an allergic sensitivity, it is usually due to one or more of the proteins in milk. The proteins in goat's milk are closely related to those in cow's milk so replacing one type of milk with the other usually doesn't make any difference. There will only be a benefit in switching if the protein or component in cow's milk is not present in goat's milk. Although cow and goat's milk are similar in composition, goat's milk is a greater source of calcium but a poorer source of folate.

Milk allergies are more common in very young children and most tend to grow out of them or build up a tolerance to milk.

Lactose intolerance
Lactose is a type of carbohydrate or sugar that naturally occurs in milk from any mammal, including humans. Normally, an enzyme in the small intestine - called lactase - breaks down this sugar to glucose and galactose that can be absorbed into the blood stream. Some people don't produce enough lactase, which means the lactose skips the usual digestion process resulting in lactose maldigestion. Undigested lactose is broken up by the bacteria that live in the large intestine resulting in gas, bloating, pain and sometimes diarrhoea. This condition is called 'lactose intolerance' and is largely genetically determined. You can either be born lactose intolerant, or develop it later in life. About 70 per cent of the world's population has difficulty digesting lactose, especially people of Asian, Aboriginal and Pacific island descent. Many people with lactose intolerance have a particular tolerance level, which allows them to consume some lactose with minimal symptoms. Symptoms of lactose intolerance (abdominal pain and distension, watery stools, flatulence) are similar and thus often confused with symptoms of the irritable bowel syndrome (IBS). People with IBS are not lactose intolerant, but tend to have difficulty tolerating fat which means full cream milk will be less well tolerated than reduced fat milk - the reverse is true for people with lactose intolerance. If you think you may be lactose intolerant, see your doctor.
Milk and milk products are highly nutritious, so people who suffer from lactose intolerance should not give them up entirely. You can still consume milk, but only in moderate quantities. Most people with this condition can tolerate 240ml of milk per day, but individual tolerance levels need to be determined. You can now buy milk which has had the lactose broken down making it lactose free e.g Zymil, Lactaid.

Most people can tolerate the amount of lactose found in:
- Half a cup of full cream milk
- Three quarters of a cup of icecream or yoghurt
- Half a cup of white sauce
- Three quarters of a cup of unripened cheeses like cottage or ricotta.
Full cream milk contains less lactose than calcium enriched milks so tends to be better tolerated. Fermented milk products - including some yoghurts, mature/ripened cheeses (like cheddar cheese, fetta and mozarella) , and butter - generally pose no tolerance problems. The amount of lactose in yoghurts can vary depending on such factors as the amount of milk solids added during its manufacture. Also, if the yoghurt contains 'live' bacterial cultures the bacteria can break down some of the lactose in the yoghurt; if the bacteria survives the passage through the stomach, may also help digest the lactose in the intestine. The label on the yoghurt packaging should state if it contains live cultures. Foods that contain lactose are better tolerated if eaten with other foods or spread out over the day, rather than being eaten in large amounts at once.

Foods that may contain hidden lactose include:
Biscuits/cakes (if milk/milk solids are added)
Cheese sauce
Cream soups
Custard
Milk chocolate
Pancakes/pikelets
Scrambled eggs
Quiche
Muesli bars
Some breads and margarine (containing milk)

If trying to avoid lactose, look for the following ingredients in lists on food labels: milk solids, non-fat milk solids, whey and milk sugar.

Heated milk products - such as evaporated milk seem to be better tolerated than unheated foods because the heating process breaks down some of the lactose to glucose and galactose
Soy foods are lactose free and a good substitute for milk or milk products. Soymilk, custard, yoghurt and cheese is now widely available in Australia.Foods that contain lactose are better tolerated if eaten with other foods or spread out over the day, rather than being eaten in large amounts at once.

Other sources of calcium
Although milk is an excellent source of calcium, it isn't the only one. Other good sources include:
Cheese, especially hard cheeses
Yoghurt
Calcium-fortified soy products
Fish with edible bones, like canned salmon and sardines
Some nuts (almonds, brazil nuts)
Sesame seeds (tahini)
Dried fruit (e.g figs, apricots)
Dark green leafy vegetables (e.g Asian greens like bok choy).

The calcium in milk has high bioavailability - which means it is easy for the body to absorb. The lactose in milk helps its absorption. Calcium from vegetables or supplements often have low bioavailability.

Daily calcium requirements
To meet the body's daily calcium requirement, it is recommended that you eat three serves of dairy products a day. One serve is equivalent to:
· 250ml of milk
· 35g (1 matchbox) of cheese
· 200g yoghurt
· 200g (4 small scoops) of icecream.

Milk products which are poor calcium sources include cream, cottage cheese, ricotta cheese and cream cheese. People who do not eat any dairy products may have difficulty meeting their daily calcium requirements. They will need to pay special attention to other dietary sources of calcium.


Things to remember
Milk is an excellent source of calcium and other essential nutrients.
There are many modified milks available
Reduced fat milk and milk products may help in the prevention of oesteoporosis and diabetes and in the managment of high blood pressure and body weight.
Lactose intolerance is caused by an inability to digest milk sugars.
Yoghurts with live cultures and mature cheeses tend to be low in lactose.
Inclusion of flavoured milks do not adversely alter a healthy diet and they are preferable to soft drinks/fruit drinks - especially for children.

Article co-authored by Better Health Channel
(Australian -Victorian Government website)

 

Last updated April 2005