Geschatte leestijd: 14minutenMilk is a food item about which almost everyone has a strong opinion, both in terms of taste and its impact on health. Some love it, others can’t stand it. Some include it as a staple part of their diet while others consciously eliminate it. At times, you hear about how milk is packed with good nutrients, while other times you hear that adults shouldn’t drink milk at all.
It’s time to put everything in order, it seems. I will address the various forms of milk and derived products, their nutritional value, and their impact on health from various perspectives.
However, I will limit myself to cow’s milk.
Due to the multifaceted nature of the milk topic and the risk of it becoming an excessively long article, and with some people waiting for this piece for a while, I will write this in two parts.
This first part mainly focuses on the impact of milk on body composition through muscle mass and body fat percentage, as well as on lactose intolerance, allergies, and acne. Part II will further explore its impact on general health, such as the relationship between milk and diabetes and milk and the risk of cardiovascular diseases.
The production of milk
A cow must give birth to a calf annually to produce milk. A cow produces an average of 21 liters of milk per year. Cows are milked twice a day, with the milk going directly to large cooling tanks through pipes. The milk is collected by the dairy company every three days. It is checked for the presence of veterinary drugs, bacteria, and the amount of fat and protein. The more fat and protein the milk contains, the more the farmer gets paid. In the dairy factory, the milk is stored, and the fats are separated from the milk. Then the milk can be processed into various end products such as whole, semi-skimmed, and skimmed milk by adding the corresponding amounts of fats. This ensures that a certain milk product always contains the expected amount of fat and does not differ due to different sources (different cows and feed). Subsequently, the various types of milk undergo several steps to improve and maintain quality.
Pasteurization: The milk is heated to 72 degrees to kill bacteria.
Homogenization: The milk is pressed through small holes, making the fat globules smaller and better dissolved in the milk. This prevents the fat from floating on the milk and maintains its white color.
Afterward, the milk is cooled and stored in cooling tanks and is essentially ready for packaging and sale.
Long-life milk: Sterilized milk
To prolong the shelf life of milk, it can be heated again. This process is called sterilization. Due to the second heating, the taste differs compared to ‘fresh’ (but technically pasteurized) milk. Nowadays, Ultra High Temperature (UHT) heating is often used. This is a much higher temperature applied for a much shorter duration, reducing the difference in taste.
Milk and derived products: quark, cheese, yogurt, etc.
The average farmer sells only a small part of the milk. Only 7% is sold as milk. More than half of the milk is processed into cheese on the farm, while over 5% is processed into desserts such as yogurt.
Nutritional values in milk
Below are the nutritional value tables as compiled by NEVO (Dutch Food Composition Database, part of RIVM). First, I’ll show the values, then I’ll discuss the “most important” ones separately.
Food Item
Energy (kJ)
Energy (kcal)
Protein (g)
Carbohydrates (g)
Fat (g)
Water (g)
Semi-skimmed milk
192
46
3.4
4.6
1.5
89.4
Skimmed milk
150
35
3.7
4.9
0.1
90.3
Whole milk
258
62
3.3
4.5
3.4
87.6
Nutritional values in milk: Protein
Milk is a source of protein. In fact, it’s the source of the most sold protein supplements. Milk contains hundreds of different types of proteins, most of them in very small quantities. These are classified in various ways, for example, into casein (80%) and whey (20%), or into the classes casein, albumin, and globulin. The following distribution is more accurate (1).
Concentration of proteins in cow’s milk
Conc. in milk % of total
g/kg protein
w/w
Casein
Alpha-s1-casein
10.0
30.6
Alpha-s2-casein
2.6
8.0
Beta-casein
10.1
30.8
Gamma-casein
3.3
10.1
Total casein
26.0
79.5
Whey proteins
Beta-lactalbumin
1.2
3.7
Beta-lactoglobulin
3.2
9.8
Blood Serum Albumin
0.4
1.2
Immunoglobulin
0.7
2.1
Other
0.8
2.4
Total whey proteins
6.3
19.3
Fat Globule Membrane Proteins
0.4
1.2
Total Protein
32.7
100
Source: Dairy Processing Handbook, TetraPak, Sweden
Whey is particularly popular because of its fast absorption into the body, making it very suitable for consumption immediately after training or upon waking up after a period of sleep when the body hasn’t received protein (leading to muscle breakdown). Casein, due to its slower absorption, is more suitable, for example, before sleeping to ensure protein intake during sleep.
In pure milk form, you get a combination of both. On one hand, an advantage because you get protein very quickly (whey) and over a longer term (casein), providing a gradual release (see also further). On the other hand, sometimes you want specific protein, making supplements based solely on whey or casein more attractive. Another big difference with supplements is the relative amount of protein you get. Supplements can contain up to almost 100% protein depending on how the protein is filtered, while milk consists of “only” 3 to 4 percent protein.
I’ll limit myself here to the protein in milk and not delve too much into protein in supplements as they are often discussed enough on this site.
Fresh milk vs. long-life milk: Which proteins are ‘better’?
You sometimes hear about worse nutritional values of long-life (UHT-sterilized) milk because it’s heated at high temperatures to kill microorganisms as described above. Heating at high temperatures could break the protein chains, making them less useful. French researchers decided to investigate this (2). In addition to “fresh” milk (PAST*) and sterilized milk (UHT), they also looked at microfiltered milk that was made long-lasting by sieving out microorganisms (MF).
In the graph beside, you can see the amount of proteins absorbed into the blood per type of milk and how quickly. It’s clear that the protein from the most heated milk, UHT, is absorbed the most and the fastest. This is probably because the connection between the long chains of protein has been loosened or broken, allowing this to happen more quickly during digestion.
However, these “fast proteins” are also excreted more quickly by the body. In the graph beside, you can see how much of the protein they found in the urine, indicating the speed and extent to which the protein is excreted.
The speed of protein absorption and its duration are important for contributing to muscle growth. In simple terms, the faster proteins contribute more to a higher anabolic, muscle-building effect, while the slower proteins mainly limit muscle breakdown. More on this later.
* “Fresh milk” as bought in stores is also heated but at lower temperature (“pasteurized”)
Milk as a sports drink
There are various studies indicating the added value of milk as a post-workout drink. Researchers from Texas observed an increase in protein synthesis, the production of new protein leading to muscle growth, by drinking (whole) milk after training (3). This protein synthesis occurred in response to resistance training and the intake of amino acids (protein is made up of amino acids). In this study, they mainly measured the absorption of the amino acids phenylalanine and threonine in the blood to represent the other amino acids.
Ingestion of milk following resistance exercise results in phenylalanine and threonine uptake, representative of net muscle protein synthesis. These results suggest that whole milk may have increased utilization of available amino acids for protein synthesis
T.A. Elliot, University of Texas
They also found that whole milk caused an almost 3-fold greater uptake of amino acids compared to skimmed milk.
Chocolate milk as a sports drink
“But I don’t like milk”.
Okay, I will soon address all good reasons not to drink milk, such as lactose and cow’s milk protein allergies.
“Don’t like it” belongs in the same category as: “I didn’t have time to train”, “I don’t have the opportunity to eat regularly at work”, “It’s bad weather, so I won’t train”, “My left pinky hurts so I won’t go for a run”, “The sun and Jupiter aren’t aligned”. All excuses not to do what you should be doing to achieve the goals you’ve set for yourself.
Don’t worry, research has also been conducted for those who are less motivated, just like there are zumba classes for people who want to move more but need sound, company, and an instructor to get them off the couch and into motion. Research has also looked into whether chocolate milk has beneficial effects as a sports drink (4).
The choice for chocolate milk in the first study I’ll show isn’t necessarily made for people who don’t like regular milk, but because of the higher amount of carbohydrates chocolate milk contains compared to milk. Chocolate milk contains about 25 grams of carbohydrates (partly lactose) per 100 grams compared to a maximum of 5 grams of carbohydrates (completely lactose) in milk. Also, there’s usually over ten grams more fat in chocolate milk. However, the researchers from Southern Connecticut State University were primarily interested in the effects of the proteins in combination with the carbohydrates, so they used skim, fat-free chocolate milk (4).
They had experienced runners drink fat-free chocolate milk for two weeks after 45 minutes of running (at 65% VO2-max). In the three hours following, they looked at the influence on, among other things, protein synthesis. They found that chocolate milk led to increased protein synthesis (which under the right conditions leads to muscle growth).
The effects of consumption of (fat free chocolate) MILK after endurance exercise on FSR, signaling molecules of skeletal muscle protein turnover, leucine kinetics, and performance measures suggest unique benefits of milk compared with a CHO-only beverage.
W.R. Lunn, Southern Connecticut State University
However, other American researchers from James Madison University, Harrisonburg, came to a different conclusion (5).
They had soccer players do a ‘normal’ training for a week followed by a week of ‘extra intensive training’ to see the effect of chocolate milk on recovery and performance during the recovery from an intense training period, comparing it with carbohydrates. They looked at fatigue, muscle soreness, and quadriceps strength (isometric).
They found no differences except for creatine kinase, among other indicators of the degree of muscle damage.
…with no differences between treatments. No treatment*time effects were observed for Mb, muscle soreness, fatigue ratings and MVC. However, serum CK was significantly lower (p < 0.05) following four days of ITD with CM (316.9 +/- 188.3 U.L-1) compared to CHO (431.6 +/- 310.8 U.L-1).
S.F. Gilson, James Madison University
Although they didn’t see differences in performance, fatigue, and muscle soreness, chocolate milk resulted in lower creatine kinase levels. This suggests less muscle damage because recovery with chocolate milk was better. The researchers suggest further research to determine if this makes a difference in the long term.
Milk-based proteins promote muscle protein accretion to a greater extent than do soy-based proteins when consumed after resistance exercise. The consumption of either milk or soy protein with resistance training promotes muscle mass maintenance and gains, but chronic consumption of milk proteins after resistance exercise likely supports a more rapid lean mass accrual.
S.B.Wilkinson, McMaster University, Hamilton, Canada
The same researcher was also involved in another study at McMaster University (but not as the principal investigator) examining the differences between milk, soy, and carbohydrates after training (12). In addition to comparing with carbohydrates, muscle growth and strength increase were measured (in young, novice weightlifters) instead of the amount of amino acids in the blood. There was no difference in strength among the three groups. However, muscle growth differed. Muscle size increased more with milk than with soy and carbohydrates.
We conclude that chronic postexercise consumption of milk promotes greater hypertrophy during the early stages of resistance training in novice weightlifters when compared with isoenergetic soy or carbohydrate consumption.
J.W. Hartman, McMaster University, Hamilton, Canada
“Milk is good for everyone,” including women*
Apparently, it’s a popular topic there in Hamilton, Canada because colleagues looked into whether the same applied to women based on the aforementioned research. The results were similar (13).
Thus, post-exercise consumption of milk vs isoenergetic carbohydrate resulted in greater muscle mass accretion, fat mass loss and strength gains in women after 12-wk of resistance training. Our results parallel those shown previously in men.
A.R. Josse, McMaster University, Hamilton, Canada
*No worries. I’ll address the incorrect saying, “Milk is good for everyone,” later on.
Nutritional Values in Milk: Fats
The amount of fat in fresh, pasteurized milk varies, mainly due to differences in nutrition. On average, it contains about 4% fat, but this can go up to 5%. As mentioned, milk is separated from fat in the factory and then the fats are added back in the desired amount:
Whole milk: Contains at least 3.5% fat, of which slightly more than half is saturated.
Semi-skimmed milk contains at least 1.5% – 1.8% fat, of which about half is saturated.
Skimmed milk: Contains a maximum of 0.5% fat.
Some of these fats consist of trans fats, and a smaller portion consists of conjugated linoleic acid (CLA).
Semi-skimmed milk is the most sold. About 87% of all milk sold is semi-skimmed, 7% is whole, and 6% is skimmed.
One reason why some people avoid milk, besides allergies and taste, is the amount of fats in milk. This reason is particularly heard from people who watch their fat intake in their diet in general, which is why you may hear it relatively often in the gym. This is also because there is often a choice between adding milk or water to, for example, a shake after training. While others drink Brinta with milk, they replace the milk with water to eliminate the fats. Apart from taste, you should consider whether the amount of fats in milk should be a reason not to drink milk.
Fats in Milk: Does Milk Make You Fat?
Correct ratio of fats and protein, relatively few carbohydrates
Firstly, skimmed milk contains little to no fat. Moreover, the ratio of protein to fat is favourable. Because of the milk fat, it contains relatively many calories compared to protein or carbohydrates. Fat provides more than twice as much energy per gram than proteins or carbohydrates: 9 kcal/g instead of 4 kcal/g. With almost all food, it is not only the fat but also the protein and carbohydrates that provide energy, so you can better compare the caloric value of foods on the basis of 100 g.
Table 1 shows the energy distribution of the macronutrients in various types of milk:
Whole milk
Semi-skimmed milk
Skimmed milk
61% fat
30% protein
9% carbohydrate
38% fat
46% protein
16% carbohydrate
6% fat
52% protein
42% carbohydrate
In short, skimmed milk contains a little more protein, a little more carbohydrates, and a little less fat than semi-skimmed milk. Semi-skimmed milk, on the other hand, contains less of all three macronutrients than whole milk, but the ratios of proteins, fats, and carbohydrates are comparable to whole milk.
Despite the relatively high caloric value of milk, it is still a drink that is relatively low in calories. This is because it has relatively few carbohydrates and is low in sugars. Skimmed milk even contains no added sugars. The maximum amount of sugars in whole milk is 5 grams per 100 grams. The amount of sugars in semi-skimmed milk and skimmed milk is lower because milk sugar is lost with the fat that is removed.
In conclusion, it’s not necessarily the fats in milk that make you fat, but rather the overall caloric intake compared to your energy expenditure.
Fat percentages can be deceiving
One final note about the percentages of fats in milk: sometimes they can be misleading. When you drink 200 ml of semi-skimmed milk, you will receive a few grams of fats, and that is all. But in products made from milk, such as cheese and yogurt, the amounts can be quite large.
And what to think about whole milk powder? It contains over 26% fat, 26% protein, and 37% carbohydrates (and that without added sugars). So watch out with whole milk products, but also semi-skimmed milk products. Also, because fat tastes good, it is a taste carrier in many products. This means that other ingredients that we want to eat less of (sugars and salt) are often added to improve taste. These can make the product a less healthy choice. But it’s not just about the taste, but also the preparation. Whole milk can be used for deep frying, while skimmed milk will not work because it contains much less fat.
So: pay attention to the nutritional value on the packaging, because milk can also contain quite a lot of fats.
In the future, I will dive deeper into this subject and also go into the research on which type of milk is best for drinking, for example, before and after training.
Sources:Wilkinson SB, et al. Consumption of fluid skim milk promotes greater muscle protein accretion after resistance exercise than does consumption of an isonitrogenous and isoenergetic soy-protein beverage. Nutrition. 2007.Hartman JW, et al. Consumption of fat-free fluid milk after resistance exercise promotes greater lean mass accretion than does consumption of soy or carbohydrate in young, novice, male weightlifters. Am J Clin Nutr. 2007.Josse AR, et al. Body composition and strength improvements after the consumption of milk protein during resistance training. Med Sci Sports Exerc. 2012.
For someone who wants or needs to consume no more than 3 grams of lactose, these differences are very important. If you consider 30-35 grams of protein, which is a fairly typical amount for a shake, then someone could have 3 shakes with whey isolate without experiencing any symptoms. The same shake, but with concentrate or non-filtered whey, would immediately cause symptoms.
When it comes to protein supplements, you can assume that all carbohydrates come from lactose, so you can calculate how much you can have. For other supplements, it’s always more difficult because it’s hard to determine whether and to what extent the carbohydrates come from lactose. In most supplements containing protein, you should consider lactose. Exceptions exist when the protein is derived, for example, from soy or rice, although soy (which is not milk but a juice) contains other carbohydrates that can sometimes cause the same reaction in lactose-intolerant individuals.
Elimination-provocation test: “How intolerant am I to lactose?”
You can see that it can be important to know how intolerant you are to lactose. If you can tolerate 10 grams, you can still use quite a bit of protein (powder) before experiencing symptoms. But how do you find out how (in)tolerant you are to lactose?
To determine if you are lactose intolerant, there are various tests such as the lactose intolerance test, the hydrogen breath test, and the stool acidity test. These are all tests that can be performed in the hospital or by a general practitioner. However, there is also a test that you can perform yourself and that allows you to test the degree of your lactose intolerance. The so-called Elimination-provocation test involves first eliminating all lactose from your diet to see if the symptoms you had disappear. Then, after a period without symptoms (if they have indeed disappeared), you add lactose again to see if the symptoms recur. If this happens, you know you are intolerant to lactose. If the symptoms do not disappear during elimination or do not recur during the provocation phase, there was very likely another cause for your symptoms.
You can also use this test to measure how (in)tolerant you are to lactose by repeating the test, but gradually increasing the daily amount of lactose during the provocation phase. For example, start with 2 grams per day and see at what amount the symptoms return.
Of course, you can choose to avoid all lactose, but it is wise to look for other sources of calcium. Milk is an important source of calcium, and a lack of it can lead to other symptoms.
“Not being too intolerant towards lactose tolerance”
Some researchers warn against wrongly diagnosing lactose intolerance because symptoms suggestive of this condition may be caused by something else. According to them, the numbers of people with lactose intolerance are therefore greatly exaggerated. Many people who self-report as lactose intolerant turn out not to be lactose intolerant at all. Many people whose laboratory results indicate lactose intolerance can consume the daily recommended amount of milk or other forms of dairy without experiencing gastrointestinal symptoms. Not only does the presence of lactose intolerance not necessarily lead to symptoms, but conversely, the known symptoms do not necessarily indicate lactose intolerance. Moreover, consuming dairy products can also increase tolerance to lactose when the amount of dairy is gradually increased. In one study, tolerance to lactose increased from 42 grams per day to 70 grams per day in just ten days by gradually increasing dairy intake. That’s almost a doubling in just a week and a half! How this tolerance increases is not clear. One theory is that it is not the amount of lactase enzyme that increases, but that the bacteria in the intestines become more effective at processing lactose.
Milk is sometimes demonized unjustly. This can lead to other nutritional deficiencies, including a lack of calcium. In the US, dairy provides 73% of the calcium people consume. This is likely to be similar in our country, perhaps even more. A calcium deficiency can lead to osteoporosis, high blood pressure, and possibly certain forms of cancer.
This is one reason why I believe the elimination-provocation test should be preferred, as it simply tests in practice whether and at what amount you experience symptoms when drinking milk. Various studies emphasize the importance of personally determining your tolerance by observing at what amount of lactose you experience symptoms.
Tolerance for lactose is very individual
People often think that you can either tolerate lactose or not, but that’s not how it works in practice. The amount of lactose you can tolerate varies from person to person. Some people can tolerate a large amount of lactose while others experience symptoms even when consuming small amounts. The latter group has been diagnosed with lactose intolerance. This difference is related to the amount of lactase enzyme that is produced by the body. This enzyme breaks down lactose into glucose and galactose, which can then be absorbed by the body.
Not only does the amount of lactase vary from person to person, but the activity of the enzyme also varies. Some people produce a normal amount of lactase, but the activity of the enzyme is low. This is referred to as lactase non-persistence. This means that the lactase enzyme is present, but not active or less active than normal. These people can therefore have symptoms even though they produce the enzyme, albeit in insufficient quantities.
Some people even have symptoms when they consume lactose in the form of yogurt or cheese. This may seem strange because these products contain less lactose than milk. However, the symptoms are likely due to other substances present in the product.
It is also important to realize that lactose intolerance is not the same as a milk allergy. A milk allergy is an abnormal immune response to one or more proteins in milk and can be life-threatening, especially in children. Lactose intolerance, on the other hand, is a digestive disorder that occurs when lactase, an enzyme needed for proper digestion of lactose, is deficient or absent.
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