Milk: understand everything in 2 min
For several years, there has been controversy about the positive health effects of milk consumption. There is an abundance of scientific literature on the relationship between milk and the onset, prevention or treatment of certain diseases. This is why it is important to make a critical and objective judgment. The statements below are intended to reflect current scientific data. Some elements of controversy, which are not supported by scientific research, are briefly presented taking into account the available literature on the subject.
Active ingredients and properties
Milk contains several vitamins and minerals, including calcium and vitamin D (added), which are essential for maintaining bone health . In addition, milk calcium may play a role in the prevention of various diseases such as cardiovascular disease , high blood pressure and obesity . Other bioactive compounds are present in milk and are also said to have health effects. This is the case with lactoferrin, a protein that plays a role in the fight against infections . It would also protect against certain types of cancer .
|Milk and mucus
Many people who suffer from colds, flu or sinusitis tend to avoid milk in order to decrease the production of mucus. This practice would be unfounded. According to studies, consumption of milk does not increase the production of mucus. Of note, more significant symptoms are reported by individuals who believe that milk causes mucus secretion 44-45 .
Cardiovascular illnesses. Milk, which contains saturated fatty acids and cholesterol, has long been suspected of causing cardiovascular disease. However, it also contains calcium. More and more studies confirm that the consumption of milk and calcium is not associated with cardiovascular disease and myocardial infarction 1-4 . Low milk consumption has even been linked in some studies to an increased risk of cardiovascular disease 5-6 . The amount of milk to consume to prevent cardiovascular disease has not been determined at this time, although the risks seem to increase for individuals who consume less than two servings of milk per day.
Blood lipids. In a recent study done in Quebec, the authors reported that high calcium intake from dairy products, including milk, was linked to a better profile of blood lipids 7 . Blood cholesterol is an important risk factor for cardiovascular disease. Consuming milk would maintain higher blood levels of HDL cholesterol (good cholesterol) 8 , which is believed to be a protective factor for cardiovascular disease. Milk fats are also associated with a composition of LDL cholesterol particles (bad cholesterol) 9 which would be less harmful for heart health.
|Trans fats in milk?
Dairy products, such as milk, naturally contain small amounts of trans fat, about 2% to 5% of their total fat content. The digestive system of ruminant animals has bacteria capable of producing this type of fat.
One serving (1 cup or 250 ml) of 2% milk contains about 0.2 g of trans fat, compared to a donut that contains up to 6 g of trans fat. In Canada, the average consumption of trans fat in adults is estimated to be around 8 g per day . 47 You would have to consume the equivalent of 10 liters of 2% milk daily to reach this amount. Milk therefore contributes little to the total trans fat intake of the diet. Canada’s Food Guide recommends that people consume two glasses (500 ml) of skim, 1% or 2% milk per day as part of a balanced diet.
According to the World Health Organization (WHO), the total amount of trans fat consumed each day should be less than 1% of calorie intake. Thus, a person who consumes approximately 2,000 calories per day should limit their consumption of trans fat to 2 g 48 . Scientific data shows that dietary trans fats are harmful to health and may increase the risk of heart disease. The negative effects on trans cholesterol of trans fats produced during the hydrogenation of vegetable oils are well documented. Researchers are wondering, however, about the health effects of naturally occurring trans fats.
A recent clinical study, published by a team of researchers from Laval University in Quebec, reveals that trans fats of natural origin, such as those present in dairy products, would not be harmful for cardiovascular health, even when they are ingested in relatively high quantities (around 4 g per day). In very high quantities (about 10 g per day), natural trans fats would however have the same negative effect on blood cholesterol as industrial trans fats, namely a decrease in “good” cholesterol (HDL) and an increase in “bad” cholesterol (LDL) 49. However, it should be noted that it is impossible to consume natural trans fatty acids in such a high quantity, as part of a normal diet. This is not the case for trans fats found in hydrogenated vegetable oils.
High blood pressure. Epidemiological studies have shown that the calcium in milk can promote better blood pressure 10 . In addition, a daily consumption of three to four servings of milk combined with a diet rich in fruits and vegetables could lead to a decrease in blood pressure in individuals whose blood pressure is normal or slightly elevated 11 .
Obesity. Studies show that milk calcium is associated with lower body weight 12 , as well as a more favorable body mass index (BMI) 13-14 . Low consumption of milk calcium is associated with greater adiposity 7 , particularly in women. According to some authors, milk has an anti-obesity effect 15-16 and consuming at least three servings of milk per day could promote weight loss 17 . However, a recent study showed that a diet containing more than 800 mg of calcium per day from dairy products had no effect on weight loss 18. It is important to note that the benefits of calcium consumption on obesity are mainly seen in people who are initially low calcium consumers 7 .
Osteoporosis. Milk is recognized by many scientists as an important food for bone growth and health because it contains calcium and vitamin D. It is added to milk. Calcium and vitamin D are both important nutrients for preventing osteoporosis 19 . The consumption of milk during childhood and adolescence influences the size obtained during adolescence, but can also have greater repercussions in adulthood 20-21 . Indeed, 45% of bone mass is formed during adolescence and during this intense period of growth, the consumption of milk and calcium influences the mineralization of bones 22 .
In addition, the consumption of milk and dairy products promotes better bone density, thus preventing osteoporosis 21-23 . However, there is no consensus on whether milk calcium actually has a beneficial effect on osteoporosis. Studies have shown that certain types of fractures are more common in people who regularly consume dairy products and have rather high intakes of calcium 24-25 . An American study, carried out over a 12-year period, showed that women aged 40 to 60 who consumed milk increased their risk of fractures 26. Thus, it would seem that a significant consumption of proteins (mainly from animal sources) could be associated with an increase in calcium losses via the urinary tract, leading to a reduction in bone mass or an increase in fractures 25 .
There is currently no consensus on the optimal amount of milk to consume in adulthood to prevent osteoporosis and to decrease the incidence of fractures in the elderly 27-29 . However, the World Health Organization recommends consuming a minimum of 400 mg to 500 mg of calcium per day for people aged 50 and over who live in a country where the risk of fractures is greater 19 . In Canada, it is recommended to consume 1,000 mg to 1,300 mg of calcium per day depending on age, which is equivalent, for example, to two or three servings of dairy products 30 . Drinking milk is suggested as it is an accessible way to get enough calcium and vitamin D 21,31.
|Chocolate milk, recommendable or not?
Chocolate milk, favored by children and adolescents, is a source of calcium as interesting as plain milk. Indeed, the calcium contained in chocolate milk is absorbed as well as in other types of milk 46 . However, it is important to remember that this milk is sweet and therefore provides more energy. A 250 ml serving of chocolate milk (2% fat) provides 190 calories, while the same amount of 2% fat milk provides about 150 calories. A little pleasure that must be consumed in moderation!
Diabetes. Early consumption of cow’s milk in infants may contribute to the development of type 1 diabetes in children with a family history of diabetes, although the mechanisms involved are unclear . 33 According to some authors, the physiological response is caused by an autoimmune response to bovine serum albumin, resulting in the destruction of pancreatic beta cells manufacturer insulin 34 . Breastfeeding is therefore recommended for infants. However, milk consumption could decrease the incidence of type 2 diabetes in adults. As reported in a recent study 35consuming two to three servings of milk a day could lower the risk of type 2 diabetes.
Cancer. Milk contains calcium, added vitamin D, lactoferrin, and conjugated linoleic acid, four compounds that are thought to inhibit the formation of cancer in animals 36-37 . In humans, the role of milk in the development of cancer has not been clearly demonstrated. Milk has a protective effect against certain types of cancer such as colon cancer 36 and does not contribute to breast cancer 38 . It may also play a role in prostate cancer 39 . Since the results of the studies are inconclusive, for the moment, there are no official recommendations concerning the consumption of milk in connection with cancer.
|Bioavailability of calcium
Milk and other dairy products are a major source of calcium and provide about 70% of the calcium in the diet 31-32 . Milk is not the only source of calcium. Calcium is found in other foods such as sardines, salmon, broccoli and bok choy. There is some debate as to whether the bioavailability of calcium from milk is better than that of other sources.
The bioavailability of calcium varies depending on the type of food 31 . A serving (250 ml) of milk provides about 300 mg of calcium and the absorbed fraction will be 32% while a serving (125 ml or 80 g) of broccoli provides about 35 mg of calcium and the absorbed fraction will be 61% . However, even if the calcium in broccoli has better bioavailability, about 2 ½ cups should be consumed in order to obtain the same amount of calcium absorbed as in a glass of milk 31 .
|Is milk antioxidant?||Data not available.|
|Is milk acidifying?||A little , the PRAL index of whole milk is 0.7.|
|Does milk have a high glycemic load?||A little , the glycemic load of skim milk is 4.|
Most important nutrients
See the meaning of the nutrient source classification symbols
Calcium. Milk is an excellent source of calcium. This mineral is by far the most abundant in the body. Calcium is mainly stored in the bones, of which it is an integral part. It contributes to the formation of bones and teeth, as well as to the maintenance of their health. Calcium also plays an essential role in blood clotting, maintenance of blood pressure and contraction of muscles, including the heart.
Phosphorus. Milk is an excellent source of phosphorus (see our fact sheet on Phosphorus nutrients ). Phosphorus is the second most abundant mineral in the body after calcium. This mineral plays an essential role in the formation and maintenance of healthy bones and teeth. In addition, it participates among other things in the growth and regeneration of tissues, helps to keep the blood pH at normal and is one of the constituents of cell membranes.
Vitamin B2. Milk is an excellent source of vitamin B2, a vitamin also known as riboflavin . Like vitamin B1, it plays a role in the energy metabolism of all cells. In addition, it contributes to tissue growth and repair, hormone production and the formation of red blood cells.
Vitamin B12. Milk is an excellent source of vitamin B12. This vitamin works together with folic acid (vitamin B9) to make red blood cells in the blood. It also participates in the maintenance of nerve cells and cells that make bone tissue.
Vitamin D. Milk is an excellent source of vitamin D. Vitamin D is closely linked to the health of bones and teeth, making calcium and phosphorus available in the blood, among other things for the growth of bone structure. Vitamin D also plays a role in cell growth, including cells in the immune system. Note that vitamin D is added to milk.
Selenium. 1% and 3.25% milk are good sources of selenium, while skim and 2% milk are only sources. This mineral works with one of the main antioxidant enzymes, thus preventing the formation of free radicals in the body. It also helps to convert thyroid hormones to their active form.
Pantothenic acid. (Vitamin B5). Milk is a good source of pantothenic acid. It is part of a key coenzyme in the energy use of the food we eat. It also participates in several stages of the synthesis of steroid hormones, neurotransmitters and hemoglobin.
Vitamin A. Skim milks, 1% and 2% are good sources of vitamin A, while 3.25% milk is only one source. Vitamin A is one of the most versatile vitamins, playing a role in several body functions. This vitamin promotes, among other things, the growth of bones and teeth. It keeps the skin healthy and protects against infections. In addition, it plays an antioxidant role and promotes good vision, especially in the dark.
|What is a “portion” of milk worth?|
|Weight / volume||
Skim milk, 250 ml (1 cup)
Milk 2% fat
Milk 3.25% fat
|Protein||8.7 g||8.7 g||8.5 g||8.3 g|
|Carbohydrates||12.8 g||12.9 g||12.1 g||11.7g|
|Dietary fiber||0.0 g||0.0 g||0.0 g||0.0 g|
Source : Health Canada. Canadian Nutrient File , 2005.
Pasteurized milk and raw milk
The pasteurization , heat treatment, provides a healthy milk by extending the shelf . Pasteurizing milk can control bacterial contamination, destroy pathogens, and eliminate certain enzymes that produce unpleasant flavors. Due to their nature and their physical and chemical properties, the nutrients present in raw milk are sensitive to heat treatments. Thus, pasteurization decreases the content of vitamins B1, B12 and C – a loss of about 10%. However, it has no effect on other vitamins such as A, D and B2 40 . Pasteurization has no effect on the amount of protein, fat, lactose and minerals present in milk 40-41. In addition, a study has shown that there is no difference in protein digestibility between raw milk and pasteurized milk 41 . Milk intended for consumption must be pasteurized.
The raw milk is freshly drawn milk from the udder of the lactating cow. It has not undergone heat treatments, homogenization and skimming. It retains all the properties that nature has attributed to it 42 . These natural factors include well-known nutrients such as proteins, vitamins and calcium, but also antimicrobial agents and immunological factors. Although some people claim that the consumption of raw milk by farmers and their immediate families does not have a negative impact on health, 42 there is no scientific study to confirm this fact. It should be noted that since 1991, the sale of raw milk has been strictly prohibitedin Canada by the Food and Drug Regulations. Raw milk is an environment conducive to the proliferation of pathogenic microorganisms dangerous to human health. In addition, Health Canada has recently reported in Ontario cases of E coli contamination that may be related to the consumption of raw milk. It is allowed to use raw milk for cheese production, because raw milk retains its natural flora and allows the production of various high-end products. However, the cheese must be kept at a certain temperature for a minimum of 60 days before being consumed.
Along with peanuts, eggs and seafood, milk is one of the main causes of food allergies. Cow’s milk allergy is one of the most frequent clinical syndromes encountered in young children, ranging from 1% to 5% according to studies 43 . This high frequency would be related to children with a family history of allergy, as well as the too early introduction of cow’s milk in the diet of infants 34. However, allergies to milk decrease after the age of three and almost disappear during adolescence. It is mainly the proteins present in milk which are responsible for allergic reactions, mainly caseins and beta-lactoglobulin. Breast milk, on the other hand, does not contain beta-lactoglobulin 34 . The classic manifestations of milk allergy are digestive disorders (diarrhea, vomiting, cramps and pain), respiratory disorders (bronchitis, asthma) and skin problems (eczema).
Many people are intolerant to milk because they don’t produce enough lactase, an enzyme (beta-galactosidase) found in the gut that helps digest milk sugar called lactose. Lactose intolerance is characterized by various symptoms such as bloating, gas and diarrhea.
People who are lactose intolerant may decide to avoid or consume milk by adding a few drops of enzyme (commercially sold) which makes lactose more digestible. It should be noted that individuals who suffer from lactose intolerance usually tolerate yogurt well because it contains little lactose.
Cow’s milk contains calcium and fatty acids such as conjugated linoleic acids (CLA) and omega-3 fatty acids, known for their beneficial effects on health. These fats are however present in small quantities. One serving (250 ml) of regular 2% milk contains 25 mg of CLA and 25 mg of omega-3, each representing about 0.5% of the milk fat.
Milks naturally enriched with CLA and omega-3 fatty acids are now available on the market . It is enough to modify the diet of cows by incorporating in their food ration vegetable oils rich in polyunsaturated fatty acids or, in some cases, fish meal rich in omega-3. One serving (250 ml) of regular 2% milk contains up to 100 mg of CLA and 100 mg of omega-3. In the dairy processing sector, new processes have been developed to add omega-3 fatty acids to milk during its production at the factory. Flaxseed oil, which is an important source of omega-3 fatty acids, is added to milk during processing. One serving (250 ml) of regular 2% milk thus contains approximately 20 mg of CLA and 300 mg of omega-3.
Milks enriched with calcium and ” probiotic ” milk are also found in grocery stores . Milk fortified with calcium contains about 35% more calcium than regular milk. The added calcium is of dairy origin. “ Probiotic ” milk contains lactic acid bacteria known to have a beneficial impact on the microbial balance of the intestinal flora. This milk also contains a prebiotic, that is to say a non-digestible substance which stimulates the growth or the activity of certain bacteria beneficial to the gastrointestinal tract.
By law, these new functional foods should be designated as dairy drinks, not milk.
Milk over time
|The term ” milk ,” which appeared in the language in the XII th century, comes from the Latin lac or lactis . The word then served as a radical for many other words.|
While milk is considered a staple food in the West today, this is not the case in Asia, Africa and Eastern Europe, where it is estimated that 20 % to 100% of populations suffer from lactose intolerance (milk sugar). In these populations, the body, once weaned, stops producing lactase, the enzyme that degrades lactose and makes it digestible. Several hypotheses have been put forward to explain this intolerance, some of a genetic nature, others of climate.
When did human beings realize that they could take cow’s milk for their own ends without endangering the life of their little one? First of all, it was necessary to domesticate the imposing auroch and, through the game of selection, reduce its size and attenuate its aggressive character so as to be able to approach the female without too much risk. This domestication would have occurred 7000 years or 8000 years ago, in the south of Asia. Unless one had first consumed the milk of the goat, which one had domesticated 1000 or 2000 years before on the Iranian plate.
However, as it corrupts quickly as soon as it comes into contact with air, milk as it has been universally consumed only very recently in history, unlike its by-products – cheese , the butter , the yogurt and other fermented milk – which store better and are appreciated for millennia. Not until the XIX th century and the onset of rapid transport, especially the train, so that the milk is produced and sold widely. Then, in the XX th century, producers will find themselves with significant surpluses, which will encourage them to promote dairy products, supported by health authorities. This will give milk definitively its status as an essential daily food, both for adults and for children.
Previously, it was mainly consumed by peasants, and especially by the elderly, the sick and children. In the countryside, it was not uncommon to see a child suckling from the udder of a cow or a goat. Until the XIX th century, we will keep in children’s hospitals in France goats and even donkeys, in order to treat sick children.
The need to supply milk to a city population increasingly distant from the countryside, and in the midst of a population explosion, will bring about major changes in the way in which this eminently perishable food is treated. In the first half of the XX th century, pasteurization , to counter the risk of transmission of TB from cows to humans become mandatory in Canada and twenty US states. Then comes homogenizationand, when fats of animal origin become a subject of health concern, the systematic separation in the factory of milk and its cream to recombine them according to specific proportions, namely 3.25%, 2%, 1%, with the exception of skimmed milk which should only contain 0.1% cream. Other industrial processes, such as evaporation , dehydration , extraction , to name the least complex, will make it possible to create a whole range of products from this simple food.
These processes will serve not only the retail market, but also the food industry which makes great use of it, in particular for the emulsifying, foaming, gelling, browning or dispersion properties of its proteins. There is also an increasing use of sterilization (carried out at a higher temperature than pasteurization) and ultrafiltration to eliminate pathogenic germs that resist pasteurization.
Pasteurized or raw?
|Milk is everywhere Milk
products and by-products are found, among other things, in formulas for infants, desserts, icings, ice creams and other frozen foods, baked goods, cold meats, soups, sauces, spreads, drinks, sports foods, meal replacements, liquid supplements, puddings, health bars, as well as many commercial cheeses that are not made using traditional methods.
From the moment we wanted to impose the pasteurization of milk, voices were raised to oppose it. In the years 1920 to 1930, when it became common practice, the majority of the population was also against it, because it was believed that it had the effect of destroying a good part of the nutrients, even the vital force, of milk.
This debate continues today, even within the scientific community, where doctors and nutritionists question this process, which is universally used today. Not only is he accused of modifying milk proteins and destroying part of its vitamins, as well as the useful bacteria and enzymes necessary for its digestion and assimilation, but it is suspected to be the cause of some modern diseases which incidence is constantly increasing, in particular allergies, dental caries, colic in infants, growth problems in children, osteoporosis, arthritis, heart disease and cancer . In addition, by destroying the useful bacteria whose milk is naturally rich, it would actually contribute to the proliferation of harmful bacteria downstream of the process. There is also opposition to homogenization which, by causing the release of an enzyme, xanthine oxidase, would have harmful effects on human health.
In some European countries, as well as in 28 American states, the sale of raw milk is authorized under certain conditions. However, the health authorities are clearly against it and the trend is, on the contrary, towards a tightening of the legislation in this regard.
Milk from goats and other mammals
Although, in developed countries, the cow is by far the animal most commonly raised for milk production, it is the goat that feeds the largest number of people on the planet, especially in Asia and in Africa, where 80% of all goat farms are found. In the West, its milk enjoys the reputation of some people for being healthier and more digestible than that of the cow.
The females of other species have been and, in some cases, are still put to use in various places of the world: camel in Arabia, Central Asia and Africa, buffalo (or buffalo) in Asia and to a lesser extent in Europe , sheep in the Middle East, yak in the Himalayas, zebu in certain parts of Asia, reindeer in the Lapps, donkey in Europe and in the Near and Middle East.
Always check the expiration date on the packaging.
|Aversion to milk
Among certain peoples, particularly among the Chinese, milk is often considered an impure and barbaric food. Cultural and social factors, in particular the domination at various times in the history of China by the Mongols – large consumers of dairy products – could partly explain this aversion among a people for whom, in any case, milk and products dairy never played a big role. The Chinese, who had a large source of labor, had little use of draft animals in agriculture and therefore had no access to their milk. Even today, annual consumption per person in China is only 2 kilos, while it is 68 kilos in France, 90 kilos in Canada, 97 kilos in the United States, 157 kilos in Sweden and 163 kilos in Ireland,
- In morning cereals, hot or cold.
- To suppress hunger in the middle of the afternoon or afternoon, take a glass of milk.
- Mix with eggs, sugar and vanilla for making eggnog, with fresh or frozen fruit for milkshake, or with melted chocolate, honey, cinnamon and nutmeg .
- In soups, creams, soups: cauliflower, pumpkin, parsnip, tomato, seafood.
- In the flans, omelettes, quiches, soufflés, sweet desserts, French toast, pancakes, waffles, dough, etc.
- In cakes and puddings, especially rice pudding.
- In fruit mosses.
- In salty or sweet sauces. Indispensable in the making of béchamel.
- Meat or fish can be poached in milk seasoned with salt, pepper and herbs or spices. Liver and kidneys are frequently cooked this way.
- In macaroni and cheese or other baked pasta dishes.
- In pranks.
- It can be incorporated into salad dressings.
- In veal, chicken or beef casseroles à la Stroganov.
We also use the skin of milkin the kitchen. To prepare it, pour two liters of milk into a wide-bottomed pan, heat gently until it boils, no more than five minutes. Remove from heat and let stand 24 hours in the fridge. It will then be enough, using a skimmer, to lift the skin which will have formed on the surface of the milk. To prepare larger quantities in a short time, put the pan in a hot oven and remove the skin that has formed as soon as it starts to brown. Reserve it. Repeat as many times as you need skins for the recipe. Most often, they are made into cakes: the same quantity of skins, sugar and flour is needed. Mix and place by spoonfuls on a buttered baking sheet. Bake in the oven at medium temperature for 5 to 10 minutes or until the edges are golden.
- Refrigerator : pasteurized milk, one week. Sterilized milk or UHT, up to three months until it is started. Once started, consume it in the following days. The skin of milk can be kept for 48 hours.
- Freezer : if necessary, it can be kept in the freezer for six months.
Ecology and environment
|A machine on legs
Constantly afflicted with mild diarrhea, suffering from infections that must be treated with antibiotics, and systematically showing at the slaughter of liver damage, the cow, which has become a real milk machine, has an average lifespan of three and a half years, while in good conditions it could live 12 to 15 years.
The meadow is the natural pantry of herbivores, which have a quadruple stomach allowing them to digest the cellulose fibers of grass and hay, or even the bark and stems of shrubs, as it is case for goat. However, modern so-called above-ground farming methods are making less and less room for this type of food, in favor of soy and corn concentrates, and corn silage, materials that promote rapid fattening of animals and greater milk production, but which have important consequences for their health.
For example, it is estimated that, before domestication, the cow produced on average 1,000 liters of milk per year. Once domesticated, this production rose to 4,000 liters. Today, the Holstein breed, which is gaining ground around the world, can produce 12,000 to 24,000 liters per year, and we continue to look for ways to increase these yields.
As for the composition of its milk, it differs notably from that of a cow raised on the grass. Even when it is not treated with bovine somatotropin, the genetically engineered hormone that has been the subject of so much controversy, the content of growth hormone in its milk is significantly higher due to a higher great stimulation of the pituitary gland. In addition, his milk contains much less omega-3 fatty acids and conjugated linoleic acid.
Finally, the accumulation of manure in above-ground farms is such that it poses a real headache for farmers, who are required to comply with certain environmental standards. The solution? Cut down the trees and transform the forests into cornfields, on which manure is spread so that we can get rid of these surpluses with impunity.
In Europe as in North America, this management model is increasingly questioned. We advocate the return to pasture and to less degenerate dairy breeds than Holstein, notably Jersey , Guernsey and Canadian , a small cow from Normandy who has acclimatized well in Quebec and whose milk is delicious.