We hear everything and its opposite about the consumption of dairy products. Not easily digestible for some or even straight allergenic for others, milk and its derivatives can yet be very good allies when consumed intelligently. Why is milk the subject of debate and what are the keys to virtuous consumption both nutritionally and environmentally?
A consumption to adjust
In the period of food abundance that we are going through, milk is often considered superfluous. However, as explained us Dr Schmitt (co-chairman of Bleu-Blanc-Cœur and nutritionist doctor) today there is a medical and scientific consensus to affirm that milk and dairy products constitute an essential food group, fully responding to a societal and individual expectation of good nutrition for health, and which has its place in the daily diet.
Dairy products have been the subject of a few cult advertisements that have retained our attention. They are particularly popular with young or older, as they are known to be good for their bones. The consumption advises formulated by authorities throughout their national health nutrition program are usually around 2 dairy products per day (previously 3 dairy products per day). This development is due to a suspicion of a link between excessive consumption of dairy products and the risk of developing prostate cancer in men. This is a precautionary principle that has been applied because the level of evidence is not yet sufficient to classify milk and its derivatives in the category of nutritional factors that promote cancer. Conversely, we should not go below 2 dairy products per day, as it is subject to increasing the risk of developing colorectal cancer for people over 30 years old, with this time a probable level of evidence (according to a report of the International Agency for Research on Cancer 2018).
Lactase, an enzyme sometimes capricious
The best-known component of milk is a sugar named lactose. It must undergo a transformation once swallowed to be well digested: the enzyme lactase then acts like a mini scissors which cuts the lactose into 2 smaller molecules (glucose and galactose). However, depending on our genetic capital, our ability to produce a functional lactase is variable; for example, 98% of adults in Southeast Asia have failed lactases and are therefore more frequently lactose intolerant compared to only 1% in the Netherlands. In addition, as we age, the lactases we produce are less and less effective. May those, who have concerns about digesting lactose be reassured because, in fermented dairy products (yogurts and especially cheese), lactose has almost disappeared since it was pre-digested during the fermentation process. These ripen products should therefore be favored to ensure their quota of dairy products in the event of lactose intolerance.
A concentrate of calcium and vitamins
Calcium is the main mineral present in milk: about 1200 mg per liter of milk, which matches to the amount that a child, adolescent, pregnant woman or even a senior should consume per day. For other adults it is between 900 mg and 1000 mg per day. Calcium is the subject of recommended consumption because it plays an important role in bone mineralization, muscle contraction, transmission of nerve messages and maintenance of blood pressure. The amount of calcium in dairy products depends on the degree of hydration of the food. Thicker is the yogurt or harder the cheese, more they will concentrate minerals and fat. For example, a serving of soft ripened cheese such “Camembert” provides about 150 mg of calcium, while a serving of pressed uncooked cheese such “Cantal” provides 300 mg, which is double.
The vitamin composition also depends on the degree of hydration of the food. Water-soluble vitamins (B1, B12, C) are found in greater numbers in milk, while liposoluble vitamins (which bind to lipids) will be particularly present in more fatty and compact products. This is especially the case with vitamin D which promotes the action of calcium on the bones and strengthens immunity.
The dairy products vitamin D contribution depends of countries habits. In France for example, dairy products (yoghurts, cottage cheese, cheese, milk) contribute to 25% of vitamin D intake in adults and it is 40% for children aged 11 to 17. Source: ANSES
If you do not know which milk to choose, we advise you to go for whole milk, because it will provide more vitamin D. If you choose a “Bleu-Blanc-Coeur milk”, it will also contain more omega 3 fatty acids. To be noted that a semi-skimmed milk has half fat so less omega-3 than the whole milk. And a skimmed milk, so devoid of fat will not have omega-3 and will be less rich in vitamins liposoluble such the vitamin D.
A variable fatty acid composition
There are between 35 and 45 grams of fat in a liter of milk at the exit of the udder of the cow. These lipids are composed by more than 400 different fatty acids. Important qualitative differences of polyunsaturated fatty acids exist according to the season (more omega 3 are present in the milk in spring and in summer) and also according to the composition of the feed diet of the cows: grass, flax-seed (linseed) and alfalfa consumed will lead to more omega 3 with anti-inflammatory properties in milk. At the opposite, when ruminants are fed with more corn and soybeans, omega 6 polyunsaturated fatty acids are found in greater quantities in their milk. An essential target of the Bleu-Blanc-Coeur approach aims to ensure an effective and sufficient supply of omega 3 polyunsaturated fatty acids and to limit the sources of omega 6 which are pro-inflammatory. This is a strong commitment to a healthier diet since a large part of worldwide population has a too low omega 3 intake compared to the omega 6 ingested.
A controlled impact on the environment
Milk coming from productions favouring grass feeding for cows is also more virtuous for the environment. Studies have shown that, compared to a « corn + soy + wheat » diet, a diet based on grass and plants rich in omega-3, mitigates the production of enteric methane from the rumination (up to 30 % depending of a diet). As example, the Bleu-Blanc-Coeur ecomethane approach measures the emission and supports farmers who commit in the direction of reducing methane emissions through the feed given to their cows.
Although the stakes of its composition are important, milk is not just a stack of nutrients. It is an extremely rich and regulated liquid, a synthesis of the permanent exchanges between animals, people and their environment. Dairy products must accompany us at all stages of our life and constitute an important but well thought part of our diet. Considering the frequency of consumption of dairy products, it seems essential to turn to brands and labels involving agricultural practices that are more virtuous for the environment.
Milk and dairy products are therefore foods of choice in this public health challenge and choosing them well, makes it possible to meet the legitimate expectations of consumers in terms of nutritional and ecological benefits.
- Tous gros demain, Pierre Weill, Plon, 2007.
- Laits fermentés : l’amour vache entre lactose et bactéries, La Grenouille à Grande Bouche