Green tea is rich in antioxidants and offers plenty of health benefits, but it can interact with certain foods and supplements. To get the most from your cup of green tea, try avoiding it with iron, dairy, or acidic foods.

1. Iron Supplements

Green tea contains plant-based compounds (polyphenols such as catechins and tannins) that bind to iron, preventing it from being absorbed and used by the body. This leads to low iron levels and iron deficiency.

Avoid drinking green tea when taking an iron supplement. Research shows that drinking green tea with iron may reduce its absorption by up to 90%. 

Talk with a healthcare provider if you would like to drink green tea when you have an iron deficiency. Wait at least one to two hours after taking an iron supplement before enjoying your tea. 

2. Iron-rich Foods

Drinking green tea with iron-rich foods may affect iron absorption. Foods rich in iron include:

• Fortified cereals 
• Oysters
• Mussels
• Beef
• Spinach 
• Beans 
• Lentils 

If possible, avoid drinking green tea with meals. Brew a cup an hour or two after eating to minimize effects on iron absorption. Research shows that drinking green tea at least one hour before an iron-rich meal may improve absorption. 

However, consuming iron-rich foods with vitamin C may improve iron absorption. Consider adding vitamin C-rich foods to your meal, such as broccoli, red bell peppers, citrus fruits, and strawberries. 

3. Folic Acid Supplements

The polyphenols in green tea may inhibit folate absorption. The catechins in green tea bind to folic acid, preventing the body from converting it to folate and absorbing it.

Folate (B9) is a water-soluble vitamin crucial for cell growth and neural tube development. Pregnant people require higher levels of folic acid to promote healthy fetal development and reduce the risk of neural tube defects, such as spina bifida.

If you are pregnant, ask your healthcare provider if green tea is safe.

4. Caffeine Supplements

Green tea contains caffeine, a natural drug that stimulates the brain and nervous system. Consuming green tea with caffeine supplements or caffeinated drinks like coffee could cause side effects. 

Drinking too much caffeine may cause:

• Increased heart rate 
• Higher blood pressure
• Sleep disturbances 
• Nausea
• Headaches 
• Anxiety 

Experts recommend limiting your daily caffeine intake to less than 400 milligrams. That is the amount found in two to three cups of coffee. One cup of green tea contains about 30 to 50 milligrams of caffeine. 

5. Spicy or Acidic Foods

Green tea contains compounds called methylxanthines that act as stimulants. These compounds also relax the band of muscles called the lower esophageal sphincter (LES). The LES prevents stomach acid from flowing up the esophagus, causing heartburn and acid reflux. 

Drinking green tea may increase the risk of heartburn. Avoid consuming it with spicy or acidic foods, which can lead to heartburn and indigestion. 

Who Should Avoid Green Tea?

Green tea is generally safe and well-tolerated in most healthy adults. However, certain groups may need to use caution. Talk with your healthcare provider before drinking green tea if you have any of the following health conditions:

• Pregnancy 
• Breastfeeding
• Anemia 
• Diabetes 
• Heart disease 
• Kidney disease
• Liver disease 
• Stomach ulcers 

Due to the caffeine content, children should avoid green tea. 

How to Minimize Interactions

It may still be possible to enjoy green tea despite the food and supplement interactions. Wait at least one to two hours to drink green tea to avoid absorption problems. Be mindful of the caffeine content to not exceed 400 milligrams in a day. 

Ask your healthcare provider if you are unsure if any of your medications or supplements interact with green tea. This is especially important for people with anemia because green tea inhibits iron absorption and could worsen the condition.