Nutrition advice worldwide is still often focused on nutrients to discourage. The general advice is to consume less salt, less saturated fat, and less (added) sugars. This based on epidemiological studies on the relation between intake of these nutrient and illnesses or mortality. This may seem to make sense, but the logical fallacy is the underlying assumption that the effect of foods on health is a simple sum of the effects of the nutrients a product is composed of. This does, however, not take into account the interaction nutrients can have and the effect of the food matrix on the health effect.
One prime example of this effect can be found when looking at full fat dairy products. In many countries, the official advise to consumers is to choose reduced/low fat dairy products, based on epidemiological studies that show that increased saturated fat intake relates to increased incidence of cardiovascular diseases. However, there are two problems with this advice, the saturated fats as such as well as the matrix effect.
First, with regards to the saturated fat as such. Saturated fat is a term used for a broad group of components. Within this group, it is known that different saturated fatty acids have very different effects on human physiology. But the physiological effect of the whole plethora of fatty acids present in dairy fat is much less clear.
But that’s not all, because there is also the matrix effect. There are two elements to this. First, there is a range of nutrients present in full fat dairy products that may interact with each other. For examples, the protein and minerals in dairy may change the physiological response to dairy lipids. Second, dairy products digest different depending on the structure (e.g. milk vs cheese) that may also impact the physiological response.
Studies on foods in relation to diseases and mortality do not show a negative relation between intake of full fat dairy (neither milk nor cheese) and e.g. cardiovascular disease or other diseases and mortality. This shows that nutrition advise should be based on the relation between foods and health and not the relation between nutrients and health.
In this blog, I will answer a question that has been asked to me by many different people on many different occasions: “is drinking milk bad for the environment?”. I will go into the environmental impact of dairy production, as well as give my view on whether or not this means that we should stop drinking milk.
First of all, it is important to realize that environmental impact is not easy to define. It includes many aspects: greenhouse gas emission, land and water pollution (acidification, eutrophication), and more. For this blog, I will focus on greenhouse gas emission.
Looking at the whole dairy production chain, the major greenhouse gas emission happens on the farm, which represent about two-thirds of total emission. On farm, methane and nitrous oxide emission are the major contributors. Cows produce methane during fermentation of feed in the rumen. During fermentation, methane is formed by specific microorganisms, which is subsequently emitted through burping, but also through manure. Nitrous oxide is mainly emitted from soil, where ammonia from manure & fertilizer can be converted into nitrous oxide that is released into the atmosphere. These two major sources of emission combined with all the other (relatively smaller) sources make that the dairy chain contributes about 2.8% to total global greenhouse gas emission.
But does this then mean that we should stop drinking milk? In my opinion such decision on diets should never be taken based on environmental impact alone. In the end, it is about the balance between environmental and nutritional impact. Milk has a major environmental impact, but also provides many beneficial nutrients to our diets. Studies optimizing diets based on balancing environmental and nutritional impact therefore generally show that milk consumption should not be decreased. So, due to counterbalancing of the environmental impact by its nutritional impact, my answer to the main question of this blog is no: we should not stop drinking milk due to its environmental impact. That doesn’t mean that reducing the environmental impact of dairy production is not relevant, but that’s a topic I will discuss in a separate blog.
If you are interested in plant-based dairy alternatives as a supposedly healthier and more environmental-friendly option, please read my other blog.
Kasper Hettinga, July 2018
With the recent debate about breastfeeding vs infant formula (link to NYT article), I want to add some of my own thoughts on the topic. I earlier wrote blogs about the uniqueness of breast milk (link) as well as how infant formula is made from bovine milk (link).
Breast milk is off course the inspiration for the design of infant formula. The more we have learned in the past century about breast milk, the more finetuned infant formula has become. Increasing lactose and reducing protein content have been initial steps, followed by changes in fatty acid and protein composition and mineral composition. In this way, the major nutrients in breast milk are very well mimicked in infant formula.
But breast milk is much more intricate than only these basic nutrients. It for example contains a wide range (100+) of oligosaccharides, all with their own unique properties. Although infant formula also contains oligosaccharides, these are not identical and can only mimic some of the properties of the ones from breast milk. Then we have 100’s of immune-active protein and hormones that are very different between human and bovine milk, and are even more difficult to mimic in infant formula. And finally it becomes even more complicated if we look at the cellular components in breast milk. Breast milk contains, amongst others, live bacteria, white blood cells, and transport vesicles called exosomes. We currently have no way of making or adding such components to infant formula, even though we learn more-and-more each day on their function in the healthy development of infants.
So in the end, I do not believe infant formula will ever match the functionality of breast milk. That’s why I believe we should have very strict rules for infant formula marketing, making clear to parents around the world that breastfeeding has benefits that infant formula cannot match. But that doesn’t mean that we should not try to make the best infant formula possible. My research group focuses on both sides: better understanding the health benefits of breast milk, but also understanding bovine milk to allow designing better infant formula. Because infants that are not breastfed should have the best possible alternative available to them.
Kasper Hettinga, July 2018
One of the controversies around milk drinking and human health is its role in healthy bones. Most focus is put on the calcium in milk, but epidemiological studies on the relation between calcium intake and bone health show mixed results. In this blog, I will give my perspective on this topic.
As mentioned in an earlier blog (link), milk products are an important source of nutrients. Dairy contributes proportionally more protein, calcium, magnesium, phosphorus, potassium, zinc, selenium, and several B vitamins than calories to the diet. In developed countries especially, dairy products contribute significantly to the intake of protein and these essential nutrients.
Several of these nutrients have been linked to healthy bones, especially calcium. However, nutrients do not work in isolation and beneficial health effects will not result if the intake of one or more of a set of nutrients is suboptimal. Bone health is a good example of this, because it depends on the adequate intake of several essential nutrients, including protein, calcium, phosphorus and vitamin D.
But healthy bones require more than the nutrients mentioned. Healthy bones also need sufficient exercise. Both for children (building bone mass) and in adults (loosing bone mass), a combination of the right set of nutrients and sufficient exercise is required.
This synergistic effect of several nutrients with sufficient exercise is, in my opinion, a possible explanation for the unclear results from nutritional studies on bone health. Most studies focus on single nutrients, and don’t take the whole set of nutrients plus exercise into account. It is also important to realize that not all nutrients from different food products are equally bioavailable to the body, with dairy products generally having a high bioavailability of its nutrients.
In conclusion, simply looking at calcium intake is an incorrect way to estimate the effect of dairy intake on healthy bones, as it ignores the important synergy between several nutrients and exercise, where dairy products do not only provide calcium but the whole set of nutrients. Therefore, dairy consumption can contribute to healthy bones, but needs to be complemented by exercise.
Kasper Hettinga, April 2018
About 2% of children aged 0-2 years suffer from cow’s milk allergy. Most children spontaneously outgrow this allergy. Still, for these young children, cow’s milk allergy is still an issue to the importance of milk for supplying the nutrients they need. In this blog, I will explain a now potential approach to help children outgrow their cow’s milk allergy faster.
First some background information. Milk contains two groups of proteins, caseins (the basis of cheese) and whey proteins. Proteins have a three-dimensional structure. The immune system does not recognise a whole protein, but parts (often related to the three-dimensional structure), which is called an epitope. All different milk proteins can cause an allergy reaction, making cow’s milk allergy a complex allergy that can differ a lot between children.
During industrial milk processing, milk is being heated to kill possible pathogens. During heating, whey proteins can change their three-dimensional structure. This may also change the epitopes, which may change the allergic reaction (which can both increase or decrease the response).
Besides regular heating of milk, milk can also be used in baked products (e.g. muffins or pizza). This can be called “baked milk”. From research on such products, it appears that these products often do not cause an allergic response (e.g. 75% of cases). Besides a reduced allergenic response, it also seems that children consuming baked milk outgrow that cow milk allergy faster than children that completely avoid milk protein.
Although there is already a lot of knowledge on baked milk, more research is needed before practical applications can be developed. In a collaborative research project between the Erasmus Medical Center and Wageningen University, we will study the functionality of baked milk proteins in more detail. This research aims at both increasing basic knowledge on how changes to milk proteins influence the response of the immune system, both regarding the development of an allergy as well as the outgrowing of an existing allergy. In addition, we will also do a clinical study in which this basic knowledge will be tested in children with cow’s milk allergy.
The outcomes of this new research may lead to new knowledge that can help both in strategies to prevent the development of cow’s milk allergy as well as strategies to speed up the process of outgrowing it once it has developed.
Kasper Hettinga, March 2018
Soy-based dairy alternatives are already available for a long time for consumer that don’t want, or can’t, consume regular dairy products. Recently, interest in other plant-based dairy alternatives is growing. In this blog, I will explain the health and environmental impact of changing from dairy to such plant-based alternatives.
In an earlier blog, I explained the role of dairy products in nutrient intake in our diet. Some nutrients (especially calcium and vitamins B2 and B12) are mainly obtained from dairy in our Western diet. Besides, dairy is also an important source of high quality protein in our diet. Only soy drink enriched with minerals and vitamins comes close to regular dairy in nutritional quality. Most other plant-based dairy alternatives, like almond, pea, coconut, oat and others, are not even close in composition to dairy. Most of the products are very low in protein (5 to 10-fold lower than regular dairy products) and are usually not enriched in vitamins and minerals. This makes such drinks completely unsuitable as dairy replacers, as they are not able to play a similar nutritional role in our diet.
An important reason for consumers to switch from dairy to plant-based alternatives is the environment. It is true to dairy production by cows is causing environmental pollution, especially through methane emission by dairy cows. Per liter of product, bovine milk will also have a larger environmental impact than plant-based alternatives. However, this should be seen in relation to its role in providing nutrients. As dairy provides many nutrients in our diet, the environmental impact per unit nutrient paints a different story. Here again, an enriched soy drink will turn out best, closely followed by regular dairy. But most other plant-based alternatives, due their much lower nutrient levels, will actually pollute more than regular dairy per unit nutrient.
In conclusion, most plant-based dairy alternatives are neither healthier nor environmentally more friendly than bovine milk, with the exception of enriched products, especially those based on soy protein.
Kasper Hettinga, February 2018
After my previous blog about the uniqueness of breast milk (link), it’s now time to dive into infant formula. There are many differences between breast milk and bovine milk. For example, the proteins, vitamin & minerals, lipids, and oligosaccharides all differ. For this reason, although bovine milk is the basis of infant formula, many changes need to be made to create infant formula.
For the proteins, the major difference is the lower protein level, especially of casein (the cheese protein), in breast milk, while it contains relatively high whey protein levels. So to make infant formula, whey protein is used as the basis, to make a product with lower protein content, with a concomitant shift from casein to whey protein.
One of the challenges of using whey as basis for infant formula, however, is that it contains much more minerals than breast milk. And for the infant kidneys, a lower mineral intake is important. Whey is therefore not used as-is, but after a step of mineral reduction, after which more pure whey protein is obtained. For other minerals and vitamins, several differences exist that are compensated by adding these as separate ingredients.
When it comes to lipids, more unsaturated fatty acids are present in breast milk. Therefore, plant oils are used, as these naturally contain more unsaturated fatty acids. Different plant oils, sometimes mixed with bovine milk fat, are used to reflect breast milk lipids best.
Finally, the oligosaccharide content is very different, with much higher contents in breast milk. In the past years, this was usually compensated by adding an oligosaccharide mixture (called GOS/FOS). Although this compensated the oligosaccharide level, GOS/FOS are different oligosaccharide structures. Recently, the production of a oligosaccharide structure that is also present in breast milk became possible.
This is however not the end. We still learn more-and-more each day about breast milk composition, its complexity and its beneficial effects. Challenges will thus remain to keep updating infant formula in future, to minimize these differences.
Kasper Hettinga, November 2017
I hope everyone is aware of the advice to breastfeed a baby in the first six months of life. In this blog, I’ll explain why breast milk is so special. What are the health benefits of breastfeeding? And which components in breast milk may be responsible for these benefits?
First, what are the benefits of breastfeeding? A recent literature overview by the Dutch Institute for Public Health and the Environment shows that even healthy babies in Western countries have short and long term benefits from drinking breast milk (link). There are many benefits, including for the mother. Most of the benefits for the infant are associated with the development of its immune system. So how does breastfeeding contribute to developing the infant’s immune system?
The first group of components that are important for developing a healthy immune system are immune-active proteins. Milk contains antibodies, anti-bacterial proteins, and immune-stimulatory proteins. On the one hand, this directly contributes to the defence against infections. On the other hand, these proteins also stimulate the immune system to mature, leading to a well-developed immune system for the infant.
Milk also contains complex sugar molecules that our body can’t digest, called oligosaccharides. These oligosaccharides are used by the good bacteria in the large intestine. The oligosaccharides in breast milk thereby lead to more of these good bacteria. This contributes to the immune system in two ways. First, if there are more good bacteria, it is more difficult for bacteria that may cause infections to cause problems. Second, these good bacteria, like proteins, can stimulate the immune system to mature.
Besides the proteins and oligosaccharides, milk contains many other components. For example, good bacteria that are transmitted alive to the infant, white blood cells, immune signalling components, and others. How much all these contribute to a healthy infant is not yet known. But it indicates that breast milk is a very complex liquid with many components that in synergy lead to a well-developed immune system, and thereby a healthy infant.
So what about bovine milk? The components mentioned above are only partly present in bovine milk and infant formula. But I will discuss bovine milk-based infant formula in more detail in a next blog post.
Kasper Hettinga, September 2017
One questions that is frequently asked to me, especially by journalists, is whether drinking milk is healthy. This often relates to a number of underlying questions; What are the benefits of drinking milk? What are the risks of drinking milk? Do we need to consume milk at all? In this blog, I will give my perspective on these questions.
First of all, what are the benefits of drinking milk? If we look at a Western diet, a relative large portion of minerals (calcium, magnesium, phosphorus, potassium and zinc) and B vitamins (B2, B11 and B12) originates from dairy products. A number of them (especially calcium, vitamins B2 and B12) hardly originate from other food sources in an average diet. On top of that, the protein in milk is easily digestible and provides a large share of our essential amino acid intake. Especially in a Western diet, rich in grains (bread, pasta, etc), milk provides those essential amino acids that are low in grain, making them a good complementary combination.
But what about the risks of drinking milk? There is a wide range of potentially harmful components in milk. Just try to google this topic and you may be afraid of drinking milk ever again. But are these allegations correct? I previously dealt with two topics, hormones and antibiotics in separate blog posts. In both cases, the risks of drinking milk are simply not there.
Finally, do we need to consume milk at all? Here, I believe the answer is “no, but…”. Although milk contributes many nutrients, as mentioned above, there are alternative sources for these nutrients. At the same time, one should realize that there is no single replacement that contains all these nutrients. Even plant based (e.g. soy) drinks do not provide the full nutritional quality of milk, especially when it comes to amino acid complementarity. So dairy would need to be replaced by a range of other foods. So although this is technically possible, I believe it is rather complicated and would change the diet more extensively.
So, is drinking milk healthy? In my opinion, the answer generally is yes. In our diet, it contributes many essential nutrients and leads to a well-balanced diet.
Kasper Hettinga, September 2017