Hello everyone, everything good?
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In this post I'm going to talk about lactose, a subject that has been well covered in recent years and even a little controversial with the creation of the #lacfree movement, and how it can be useful in training!
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Lactose is a sugar (therefore, a carbohydrate) found exclusively in milk, which is composed of a glucose molecule and a galactose, making it a disaccharide. It is found in dairy products and in greater quantities in milk, yogurt, powdered milk proteins such as whey and casein.
Some individuals experience gastrointestinal symptoms when they ingest lactose, which is called lactose intolerance and is caused by the inability to digest lactose in the intestine - and a lack of the lactase enzyme. Although this condition is common, most intolerant people can still eat 12-15g (the amount in a 250-300ml glass of milk) without symptoms, and tolerant people can eat much larger amounts (>80g) without problems.
There are no recommendations for lactose intake, nor is it considered how it fits into athletes' carbohydrate needs, and little is known about how it is metabolized in the context of exercise.
A recent study investigated that lactose ingested during exercise can be oxidized quickly, and effectively answered the question of whether it can be used as an energy source.
11 participants cycled for 2.5 hours at moderate intensity on three occasions. During exercise, they consumed drinks containing lactose, sucrose or water. The carbohydrate conditions contained 120g of lactose or sucrose (approximately equivalent to 4-5 carbohydrate gels), which is among the highest amounts of lactose ever investigated.
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The rates of exogenous carbohydrate oxidation to lactose and sucrose were very similar (0.56 ± 0.19 g/min and 0.61 ± 0.10 g/min, respectively) and were not significantly different. This demonstrates that lactose can be a rapidly oxidizable fuel source during exercise (at least in these moderate amounts), similar to sucrose (glucose and fructose).
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Furthermore, the lactose drink increased dependence on fat oxidation and reduced glycogen oxidation compared to sucrose, a favorable change in metabolism related to glycogen sparing.
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Therefore, not only can lactose be used as a carbohydrate during exercise if desired, but dairy foods containing lactose can also be considered as part of a pre- or during-exercise nutritional regimen due to their carbohydrate content, as the Lactose is now known to be an easily oxidizable carbohydrate substitute.
Furthermore, even relatively large amounts of lactose do not cause gastrointestinal problems in most individuals, which can be a concern for athletes who need to minimize any gastrointestinal problems during training. It's important to test it in training beforehand and not leave it to just the "important dates".
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And have you ever used or prescribed any type of dairy product before or during training?! Tell me!
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Until the next post,
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Gabi.
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References: Odell OJ, Wallis GA. The application of lactose in sports nutrition. International Dairy Journal. In press, 2020, p. 104970
