The Negative Effects of Sugar on Vitamin C Intake


From an early age, we learn that Vitamin C helps support the body’s immune system by supporting the activities of antimicrobial and natural killer cells and protecting those cells from the harmful effects of oxidative stress. Although many people reach for fruit juices rich in Vitamin C, this can be counterproductive because they also contain large amounts of sugar.

Studies have found that excessive amounts of sugar, or glucose, in the body can inhibit the absorption of Vitamin C. In the 1970s, researchers established that sugar and Vitamin C have a similar structure and enter cells using the same pathway. This makes sense because most animals use glucose to manufacture Vitamin C in their bodies. However, humans do not have the L-gulonolactone oxidase enzyme needed to synthesize Vitamin C. Instead, we must get the nutrient through foods or Vitamin C supplements.

Both Vitamin C and glucose can enter cells using a critical protein known as the Glut-1 receptor.  The Glut-1 receptor has a preference for glucose, which means it will choose sugar over Vitamin C when given the opportunity. This poses a particular challenge for white blood cells, which need as much as 50 times more Vitamin C within their cell walls than in the surrounding blood plasma to effectively combat the effects of oxidative stress.

So, instead of reaching for fruit juice or other high-sugar drinks as your source of Vitamin C, try eating vegetables that contain high amounts of Vitamin C, such as spinach, peas and broccoli. It could also be helpful to take Vitamin C supplements.