We know that fruits and veggies are packed with important and powerful antioxidants. Even drinks like coffee and tea represent a great source of free radical-combating molecules, which can fight oxidative stress and aging. However, recent scientific research showed that eating or drinking dairy products diminishes antioxidants and basically negates their actions in our bodies. And who doesn't like to have a little milk or cream in their tea and coffee, or eat cereal with fruits and yoghurt?
How much truth is there to the anti-antioxidant role of milk and other dairy products when it comes to eating plant-derived foods? Keep reading and find out.
What are antioxidants?
To understand why we care so much about drinking coffee with or without milk, we have to understand how important antioxidants are for us.
Antioxidants are usually large and complex molecules that help the body get rid off unstable and damaging products called free radicals. These free radicals are really reactive and can damage DNA, proteins, and lipids in our cells. They originate as byproducts of our metabolism, or through exposure to chemicals, pollution, and radiation.
On the other hand, antioxidants help stabilize free radicals and remove them from the body, before they cause excessive oxidative stress. High levels of oxidative stress contribute to the development of many diseases, like heart disease, cancer, and diabetes (1).
We receive antioxidants from fruits, veggies, nuts, seeds, herbs, and spices, and they can be various types of molecules, like:
- vitamins,
- minerals,
- phytochemicals and polyphenols.
How do dairy products and antioxidants interact?
Unfortunately, it's been scientifically proven that dairy proteins bind antioxidant molecules and prevent them from being absorbed by our bodies. This is particularly true for polyphenols, which are very potent and complex antioxidants found in green and black tea, coffee, and berries. Like polyphenols, also flavonoids from various citrus fruits, berries, and tea readily bind to dairy proteins (2).
However, studies have found that milk only reduces the antioxidant capacity of foods (tea and chocolate in this case) by the maximum of 30%. That still means that 70% of antioxidants remained unaffected (3, 4).
The good thing is that vitamins don't tend to bind as much to dairy proteins as other antioxidants do. Also, milk contains the most of dairy proteins (especially casein) in the form in which they can bind antioxidants. If you go for yoghurt or kefir instead, the loss of antioxidant bioavailability won't be as strong (5).
Read more about bioavailability of supplements:
- Bioavailability of Supplements – Meaning and Importance
- How does our diet influence the bioavailability of supplements?
Should I avoid milk and dairy products?
The short answer would be no. The longer answer would be yes, but only in certain situations and under certain conditions.
Basically, if you drink coffee or tea to get the full power of antioxidants they offer, then yes, you should avoid adding milk or cream. However, if you drink coffee or tea to get an energy boost, as most people do, then there's no reason for you not to add some milk. Make sure you eat more fruits and veggies throughout the rest of the day, and you will be fine.
The same goes for your breakfast, for example. If you enjoy adding some fruit to your cereal, and you like eating it with milk or yogurt, there's no special harm in that. You can still get your antioxidant amounts later by eating a piece of fruit, separately from milk and other dairy products. Also, there is less "danger" of losing antioxidants when eating yogurt, because yogurt contains significantly less casein than milk. This is also true for kefir, cheese, and other fermented products.
What about supplements? Good question! If you're taking antioxidant-packed supplements, they will be highly concentrated, and you don't want to lose those precious (and to be fair, expensive) ingredients. In that case, take your supplements with water or any other non-dairy liquids.
Explore Augment Life's offer of antioxidants below:
- Curcumin with piperin,
- Green Tea Extract,
- Ashwagandha (Withania somnifera),
- Ginseng,
- Grape Seed Extract.
How long do dairy proteins stay in our bodies?
The two main proteins in milk are whey and casein, as we previously mentioned. They are structurally very different proteins, which means they also get absorbed and metabolized quite differently.
While whey is an easily digestible protein that stays in the stomach for about 2 to 2.5 hours, casein takes considerably longer. In the acidic environment of the stomach, casein will form a gel-like material that can take up to 7-8 hours to digest (6). During this time, casein can also bind antioxidants, even though its activity drops significantly after 2 hours.
After the digestion of casein in the small intestine, some antioxidants can be released into the bloodstream, but this will depend on how strongly they were bound to casein in the first place. The safest practical advice is to take your antioxidants separately from milk if you want to absorb as many as possible. For example, take your antioxidants in the evening if you drink milk in the morning.
Conclusion
In conclusion, dairy products reduce the effectiveness of some antioxidants, especially polyphenols, by binding to them. Not all dairy products bind all antioxidants, nor do all dairy products completely reduce their actions. However, by simply eating antioxidant-rich foods separately from dairy (like milk), you can keep all the antioxidant benefits you want.
Remember that dairy has health benefits as well (protein content and gut health, for example), and don't completely avoid it. If you take antioxidant supplements, take them with water and it'll be fine.
Literature sources:
- van de Langerijt TM, O'Mahony JA, Crowley SV. Structural, Binding and Functional Properties of Milk Protein-Polyphenol Systems: A Review. Molecules. 2023 Mar 1;28(5):2288. doi: 10.3390/molecules28052288.
- Tosif MM, Najda A, Bains A, Krishna TC, Chawla P, Dyduch-Siemińska M, Klepacka J, Kaushik R. A Comprehensive Review on the Interaction of Milk Protein Concentrates with Plant-Based Polyphenolics. Int J Mol Sci. 2021 Dec 17;22(24):13548. doi: 10.3390/ijms222413548.
- Bourassa P, Côté R, Hutchandani S, Samson G, Tajmir-Riahi HA. The effect of milk alpha-casein on the antioxidant activity of tea polyphenols. J Photochem Photobiol B. 2013 Nov 5;128:43-9. doi: 10.1016/j.jphotobiol.2013.07.021.
- Jalil AM, Ismail A. Polyphenols in cocoa and cocoa products: is there a link between antioxidant properties and health? Molecules. 2008 Sep 16;13(9):2190-219. doi: 10.3390/molecules13092190.
- Xiao R, Liu M, Tian Q, Hui M, Shi X, Hou X. Physical and chemical properties, structural characterization and nutritional analysis of kefir yoghurt. Front Microbiol. 2023 Jan 11;13:1107092. doi: 10.3389/fmicb.2022.1107092.
- Bilsborough S, Mann N. A review of issues of dietary protein intake in humans. Int J Sport Nutr Exerc Metab. 2006 Apr;16(2):129-52. doi: 10.1123/ijsnem.16.2.129.
