If coffee is your first go-to after a night of interrupted sleep or insomnia, you might want to reconsider this habit. That cup of strong black coffee that you have as soon as you wake up from a poor night's sleep can increase your blood glucose response to breakfast by up to 50%. That was the findings of a new study published in the British Journal of Nutrition. A disrupted night of sleep did not affect blood sugar in the morning. However, adding a cup of coffee when out of bed after a night waked for an hour was enough to create significant imbalances (1).
Balanced blood sugar is a must to reduce the risk of conditions such as diabetes and heart diseases. Besides, it is essential to keep hormone balance, manage stress, reduce cravings, and sustain your health overall.
For some people, about 200 milligrams of caffeine (or 240-milliliter of brewed coffee) may be enough to affect blood sugar balance at any time but especially in the morning. Caffeine is a stimulant, thus can affect blood sugar if drunk soon after rising because cortisol levels are naturally higher in the morning to give us the boost needed to start a new day.
If you spend your day dealing with an energy rollercoaster or craving sugary or fatty foods, you could benefit from reducing your caffeine intake and changing the time you drink your coffee.
Caffeine effect on nutrient absorption
Caffeine interferes with nutrient absorption, especially iron, calcium, magnesium, and B-vitamins - all playing a role in keeping your energy up.
Although your focus should be on eating balanced meals throughout the day to guarantee the nutrients your body needs, sometimes, every small thing helps.
If you have a diet low in calcium due to lifestyle choices or medical conditions, you might want to reduce your caffeine intake and be aware of the time you choose to drink your cup of coffee. Calcium is easily excreted in the urine, feces, and sweat. Studies show that about a cup of coffee can reflect the loss of 5 mg of calcium. Besides, caffeine can inhibit the ability of the intestines to absorb calcium (2).
We all need iron to make hemoglobin to take oxygen through the blood to all the cells. Iron is involved in the conversion of food to energy and a cofactor for liver detoxification.
When you drink coffee with an iron-rich meal or soon after, you can reduce the absorption by up to 80% (3).
The B-vitamins have similar and supporting roles, working together. They are also often found in the same foods, and they play a role in maintaining balanced blood sugar levels, healthy skin, and making hormones.
As water-soluble vitamins, any excess ends up in the urine. Only a few days on a diet low in B-vitamins can lead to deficient levels. Caffeine might increase urination, interfering with the metabolism of some vitamins. The B12 seems to be the only one not affected because caffeine increases stomach acid secretion, which boosts this vitamin absorption.
Caffeine can impair the absorption of other minerals, including manganese, zinc, magnesium, copper, potassium, sodium, and phosphate.
The best time to drink coffee
The best time to drink a cup of coffee or other caffeinated drink might be mid-to late-morning. At that time, your cortisol level is lower. That is true if you usually wake up between 6:30 am to 7:30 am, though. Then, caffeine would not interfere with nutrient absorption from the food you ate for breakfast, and up to one hour before eating lunch, there is probably no effect on that meal either.
In general, if you eat a balanced diet and tolerate caffeine well, you should have no problem drinking an early cup of coffee either. As it always should be, listen to your body. If you go through your day without abrupt changes in energy levels, mood, or cravings, do not be afraid of grabbing a coffee for breakfast.