Ask A Scientist

Does coffee affect growth? 

Asked by: Dalton Davidson
School: Maine-Endwell Middle School
Grade: 6
Teacher: Kevin Wagstaff
Hobbies/Interests: Football, video games and basketball
Career Interest: Football player or video game designer

Answer from Lina Begdache-Marhaba

Research Assistant Professor, Binghamton University

Research area: Nutrition and obesity, cell and molecular biology, neuroscience and GERD
Interests/hobbies: Running and basketball
Family: Ali Marhaba, MD; Jade and Rani  

Caffeine is the culprit! It is a stimulant of the nervous system and acts as a diuretic. In other words, caffeine can increase alertness and frequent urination. You might think that increased alertness is perfect for school. While this might sound wonderful, caffeine exerts its action through activation of the sympathetic nervous system, inducing the "fight or flight" response. The function of this system is to prepare you for potential threats so you’re well equipped to fight or flee when in danger. To do so, your heart rate and blood pressure increase, your body shifts energy usage mostly to the brain and muscle (to think and react fast). This might sound great for stamina, however, this occurrence happens at the expense of other organs, affecting digestion, sexual reproduction, the immune system and others, which receive less blood innervation and nutrients. A long-term decrease in nutrient delivery to these organs may lead to a decline in their function. As a growing child, this could be of concern because your organs are still developing; consequently lack of adequate nutrients could impair their proper maturity and thus function. With the normal wear and tear, this will cause diseases to appear earlier in life. You might think that this is an exaggeration. Well, the problem with caffeine is, that it is addictive. After a few cups of coffee, you will lose that "magic effect" and will need to increase the number of cups to achieve the same effect. It is with increased consumption that caffeine becomes a concern.

Caffeine, as a stimulant, disrupts the normal circadian rhythm (the 24-hour cycle that regulates sleep and wake times) by diminishing the length and quality of sleep. This cycle is extremely important for development because growth hormones release peaks 2-3 hours after deep sleep and continues many hours afterward. Growth hormones are needed in certain concentrations to induce proper growth. Consequently, a long-term poor sleep quality can have a tremendous setback on physical growth and cognitive development.

Let’s address the diuretic effect. Caffeine increases loss of blood calcium via increased urination. The bone, the reservoir of calcium, compensates by releasing stored calcium into the blood to make up for the loss. Surely, this is not a healthy process for a growing child. Continuous release of calcium eventually leads to a decrease in bone mineral content, which leads to weak bones. Based on this analysis, the answer to your question is YES. On a different note most sodas contain caffeine, therefore a healthier option would be a glass of skim milk instead.

Last Updated: 9/18/13