Q: Is it true that I should start the day with hot water with lemon? What’s the story behind this theory?
A: Like most health and fitness lore, the magic properties of drinking a juiced lemon in warm water each morning is rooted in a seed of truth, but the impact of the ritual is greatly overstated. Let’s look at the three main purported benefits and any evidence to support those claims.
Lemon Improves Digestion
Actually in some cases the fruit could exacerbate issues with your stomach: Citric acid in lemons can cause or contribute to stomach pains and cramps. So where does the idea that drinking lemon juice improves digestion come from? There is a study from about three decades ago that shows citric acid can improve absorption of aluminum hydroxide (the active ingredient in most antacids). I have read online that the acidic nature of lemon juice is supposed to support an optimal acidic environment in your stomach, but this is complete speculation and, as pointed out earlier, in certain individuals could have the opposite effect.
Lemon Juice Boosts Mineral Absorption
The vitamin C found in lemon juice has been shown to enhance mineral absorption, but you don’t need warm lemon juice to get this effect. Vitamin C is one of the most ubiquitous vitamins in fruits and vegetables. We often think of citrus fruits as being the major or even only source of C, but non-yellow and orange fruits and vegetables such as bell peppers, kale, strawberries, broccoli, and spinach all contain robust amounts of vitamin C. As long as you are having a fruit or vegetable with your morning meal, then you can expect to reap the enhanced absorption of minerals at that meal.
One of the biggest health hypes about lemons and lemon juice is that they help detoxify your body. I recommend that you get very skeptical about any food or supplement claim regarding detoxification. It is such a general term that it is almost useless. The human body is so complex, what is getting detoxified? What are the toxins being removed? Where are they going? (Here, Your Non-Juice Detox: 7-Day Clean-Eating Plan.)
Regarding lemon, there is an antioxidant in the fruit called d-limonene, which is also found in oranges and is most highly concentrated in the peels of lemons or oranges. D-limonene has been shown to activate enzymes in the liver that are part of the Phase 1 and Phase 2 detoxification processes. These processes take compounds present in the liver that are toxic to cells and convert them to non-harmful or less harmful versions. These “toxins” can range from caffeine to ibuprofen.
Does lemon juice contain enough D-limonene needed to enhance this process? Probably not. A liter of citrus juice (not made with the peels) contains on average 100 milligrams (mg) D-limonene. Researchers estimate the active dose of limonene is a minimum of 500mg. D-limonene is a fascinating compound that might also work to ease gastro-esophageal reflux disease (GERD), but doses would require supplementation.
As you can see, as a citrus fruit, lemon has a handful of characteristics and compounds that contribute to good health, but one lemon juiced in a glass of warm water probably isn’t going to do much for your health.