Fertility and Pregnancy Blog


Tannin is one of the chemical compounds many plants make. Red raspberry leaf makes tannin as well. Tannins are a widely-known astringent, a polyphenolic molecule binding with organic compounds like protein. It is present in red raspberry in the quantity of 200 mg per 100 grams of red raspberry leaves. It also produces an acid called tannic acid in herbs giving out multiple benefits to people for ages. Natural and herbal remedies make use of tannins in the red raspberry leaf tea profoundly.

tannin safe to intake during pregnancy

What is Tannin?

It is a phenolic compound or can be called a group of phenolic compounds present in woody flowering plants that are known to be important deterrents to herbivores and have several applications in the industrial field. These are secondary metabolites and are sequestered in vacuoles of the plant cell functioning as a protective layer for the other cell components. Tannin occurs in the bark, leaves, roots, fruit, and wood of many plants, particularly in the bark of sumac (Rhus), myrobalan (Terminalia chebula), and oak (Quercus). 

Taste and smell-

Tannin tastes bitter and a little like an astringent. It gives out an astringent smell too. This is why tannins should not be consumed directly and rather used as an enhancer. 

Applications of tannin in different fields-

  • Commercial: In form of powder, spongy mass, or flakes. Used mainly in dyeing fabrics, photography, making ink, preserving wine, and tanning leather. 
  • Medical: To treat hemorrhoids, tonsillitis, skin eruptions, and pharyngitis. It is administered internally to help with intestinal bleeding and diarrhea. One of the most known uses of tannin is as an antidote for glycosidic, alkaloidal, and metallic poisoning. 
  • Herbal: It is one of the known compounds present in herbal teas consumed for many health benefits. It is responsible for the color, flavor, and astringency of herbal teas.

Tannins in tea

Tannin is found in various types of teas. And as the leaves of the tea plants are primarily used to make teas, the tannin level depends on it. Teas like black, green, and oolong (a mix of both green and black) have different levels of tannin compounds present in them. 

In a study conducted specifically focusing on the presence of tannins in black, green, and oolong teas, it was found out that green tea had the lowest amount of tannin content while black tea had the most. The table below shows the range of tannin content in these variants with 1 gram of each sample.


Average tannin content in %

Black tea


Oolong tea


Green tea


The reason behind the level of differences between these quantities of tannin is because of the rate of formation of tannin after organic matters are broken down. There are catechins (sometimes classified as ‘pseudo tannins’) present in tea leaves which, when oxidized, produce tannin. The more the oxidation of the eta, the more is the percentage of tannin. Teas with higher levels of tannins have strong astringency with a bitter taste, commonly noticed in black and green tea. The tannins that are found in tea leaves are thearubigins, a type of most prominently known theaflavins that are anti-mutagenic and anti-carcinogenic. The antimicrobial or antioxidant properties of dark teas are due to the presence of tannins only. 

Herbal teas on the other hand have lower levels of tannin and are mostly safe to consume. Pregnant women are told to switch to herbal solutions for their nutritional needs.

Presence of tannin in-

  1. Green tea: There are tons of choices in green tea but the level of tannin remains quite the same in each. It contains high levels of other polyphenols too. Though green tea has been proven effective in bringing down cholesterol levels, promote weight loss, reduce the risk of heart diseases and cancer, result in good skin, and improve mental health. 

Green Tea

  1. Black tea: These have the highest amount of tannin primarily due to heavy oxidation and processing/steeping methods enhancing the dark color and bitter taste. Black teas are consumed with a little added sugar or used in milk teas as the base. Both of these are prevented by pregnant women due to caffeine content as well, which is high too. 

Black Tea


  1. Oolong tea: It is lightly fermented and so is not oxidized much either. The tannin levels are quite low in oolong teas. It proves to be a refreshing and energizing drink to have due to less bitterness. Yet, as it is a mix of green and black teas, the caffeine level is high. It is not beneficial to consume during pregnancy or breastfeeding. 

Side effects and downsides of tannin

Tannin has both positive as well as negative actions depending on its usability. Decreases feed intake

Some of the negative side effects and downsides of intaking tea with tannin or consuming food with high amounts of tannins are-

  • Decreased protein digestibility
  • Binds and precipitate proteins
  • Can complex with starch, cellulose, and minerals too
  • Impairment in the absorption of dietary minerals like iron, magnesium, and calcium
  • Lowers growth rate and feed efficiency
  • Headaches
  • Stomach irritation
  • Liver damage
  • Increased chances of developing throat or nose cancer if
  • Digestive issues 
  • May cause nausea especially on an empty stomach
  • Jaw pain
  • Excess saliva excretion front the salivary glands
  • Impairment in the absorption of commonly used drugs such as antidepressants, tranquilizers, and sedatives.

Lesser amounts of tannin are known to be safer for consumption. Green tea or herbal tea is, therefore, better to intake rather than black, or oolong teas. 

Are there tannins in red raspberry leaf tea?

Red raspberry leaf has grown its significance around the world as a “woman’s herb”. You will find it is also known as pregnancy tea in general stores. Occurring from the red raspberry plant, it holds the benefits to act as a remedy for most of the issues a woman faces in her life. 

The nutritional value with the minerals such as potassium, iron, magnesium, zinc, etc. along with vitamin B and C, proves to be profoundly effective. Red raspberry leaf is mostly consumed in the form of a herbal tea and provides beneficial returns from the menstrual cycle to pregnancy. 

The herbal red raspberry leaf tea has a mild tannin level and has many benefits. The caffeine level of the red raspberry leaf is zero and therefore balances out any provisional side effects of tannin during pregnancy. Some of the benefits of the presence of tannin in red raspberry leaf tea are-

  • The polyphenolics stop diarrhea because of their astringent properties.
  • It helps reduce intestinal inflammation.
  • A good mouthwash for inflammation in the mouth and sore throat.
  • Applied on abrasions or mucus membranes to decrease vascular permeability.
  • The tannin rich-raspberry leaves are often used for wound treatment.

Is tannin safe to intake during pregnancy or breastfeeding?

Even though herbal teas are vastly used by midwives and soon-to-be mothers for stimulating contractions while soothing out pain and shortening the labor, tannins present in these teas are a compound that affects the absorption of iron and some minerals. When a tea containing tannin is consumed with a meal, it hinders the process of absorption of minerals like iron causing deficiencies and unexpected complications in the baby. 

But when tannin-containing teas are individually consumed in the day they do not affect you or the baby in any way. Having herbal teas 2-3 times a day and no more, to be refreshed is not harmful in any way. Rather it will provide you with the benefits of the herbs used. 

The same goes for you when you are in the lactating stage. Lactation is the process of milk produced by the mammary gland for the baby. The constituents of the milk produced are enriched by the dietary nutrients and minerals from the food the mother eats. And this is very important for the development of the baby and his/her immune system. It is widely known that a mother’s milk in the early stages is the backbone of a child’s development. So, if teas with tannins are taken with the food, it will affect your baby. 

The bottom line is- tannins are a necessary compound that can be both beneficial and harmful for a mother. It is the application of this phenolic compound that matters the most. If you are a mother or going to be one soon, be careful with what you eat and drink. Your diet is significant for both you and your child’s health. Consulting with a gynecologist or a dietician is a must for a proper dietary routine. Do not be scared of pouring yourself a cup of herbal tea made with refreshing ingredients like a red raspberry leaf when you are lactating or are pregnant. But, keep one fact in the context that you don’t surpass the safe level of tannin in your daily dietary schedule. 


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