Caffeine has a mild diuretic effect, which leads to an increase in urination. As a result, water-soluble vitamins, such as B-vitamins and vitamin C can be depleted due to fluid loss. Research also demonstrated that the higher the level of caffeine, the more it interfered with vitamin D absorption.
The tannins and caffeine can interfere with the absorption of many vitamins and minerals, especially iron. Caffeine also increases urination, which can decrease the concentration of water-soluble vitamins (B-complex and C). So, wait an hour after your morning brew to take supplements.
Coffee also seems to impact on the metabolism of some B vitamins like thiamine. Vitamin B12, though, looks like being a possible exception – indeed, caffeine's stimulation of stomach acid production may actually assist, instead of compromise, your body's B12 absorption.
Maybe your thinking, “vitamins, schmitamins.” But here's the deal, too much coffee depletes your supply of B vitamins, which is your natural source of energy. Caffeine also causes the body to dump other key nutrients like calcium, magnesium, potassium and iron.
Caffeine inhibits vitamin D receptors, which limit the amount that will be absorbed. Because vitamin D is important in the absorption and use of calcium in building bone, this could also decrease bone mineral density, resulting in an increased risk for osteoporosis.
Therefore, conditions that affect the gut and digestion, like celiac disease, chronic pancreatitis, Crohn's disease, and cystic fibrosis, can reduce vitamin D absorption.
Coffee does not directly affect magnesium in your body. But it halts the further absorption of magnesium gradually in your intestines. The more coffee you consume, the less your magnesium absorption rate gets. But a heavy dose of coffee can lead to magnesium depletion.
Unfortunately, the short answer is that coffee does deplete our magnesium. There are several studies that show the reasons why. Number one is that it causes an increased urinary output of Magnesium. So, when you're drinking coffee, your body pees out more magnesium.
Conditions affecting the stomach
Some stomach conditions or stomach operations can prevent the absorption of enough vitamin B12. For example, a gastrectomy, a surgical procedure where part of your stomach is removed, increases your risk of developing a vitamin B12 deficiency.
2) High Activity, High Stress
The greater stress load on your body, the greater the demand for vitamin B12 which can put drain your levels, especially when combined with a diet that doesn't contain enough of the essential vitamin.
Caffeine and nutrient absorption.
Any food or drink that contains caffeine - including coffee, tea, chocolate and some fizzy drinks - may inhibit the bioavailability of vitamins and minerals in the bloodstream and prevent the nutrients from doing their job.
Some studies link caffeine consumption with negative effects on calcium metabolism, possibly related to caffeine increasing loss of calcium in the urine, and decreasing calcium absorption in the body. Over time, having less calcium available could cause bone loss.
In general the intake of magnesium is directly related to energy intake except when the majority of the energy comes from refined sugars or alcohol. Refining or processing of food may deplete magnesium content by nearly 85%.
Milk and cheese both contain high quantities of calcium which may block magnesium absorption in some people. According to researchers, calcium-rich foods themselves aren't necessarily the problem. The issue is foods that contain a high ratio of calcium to magnesium.
Hypokalemia and Hyperkalemia
Magnesium depletion typically occurs after diuretic use, sustained alcohol consumption, or diabetic ketoacidosis.
Increased intakes of protein and fructose improve apparent magnesium absorption (magnesium intake minus fecal excretion) in humans, whereas a lowering effect occurs with consumption of cellulose and phytate.
Nutritionist Carolyn Dean points out that hypothermia isn't the only negative side affect of drinking too much water: “Clear urine may mean you're drinking too much water, and therefore, you're losing essential minerals like magnesium — lighter shades of yellow (rather than totally clear) tend to show that you're ...
Cystic fibrosis, Crohn's disease and celiac disease: These conditions can prevent your intestines from adequately absorbing enough vitamin D through supplements, especially if the condition is untreated. Obesity: A body mass index greater than 30 is associated with lower vitamin D levels.