I have a feeling that the word "ingredient" implies that it was intended to be there by human, while catechin is not an additive, but was naturally in the tea leaves. Giving another example, is polyphenol a healthy ingredient of wine, a composition, or a compound of wine?

  • What is a full sentence where you want to use ingredient/component/part (give a blank)? In a recipe, the ingredients are those items that the cook adds together. If caffeine, a naturally occurring chemical in some plants, is listed as an ingredient, then you are adding more caffeine than is already naturally there. In some sense, one doesn't bother with the 'containing' noun and just say "Caffeine occurs in tea.
    – Mitch
    Oct 4 at 13:30

5 Answers 5


Catechin is a compound itself in chemistry, more specifically a polyphenolic compound. It is not a compound of another thing. I wouldn't use ingredient, composition or component either. Constituent makes the most sense if you are talking about a chemical compound:

A constituent of a mixture, substance, or system is one of the things from which it is formed.

Caffeine is the active constituent of drinks such as tea and coffee.


Although, it is better to explain in a way that catechin is something, a compound, found in green tea. A usual way to say is:

Catechin is a naturally occuring compound found in green tea.

  • 1
    Any reason why you don't like component? Component and constituent seem like synonyms in this context. Oct 4 at 15:38
  • 3
    @WaterMolecule I feel like constituent is better for smaller essential parts that form something. Component works better for bigger distinct parts that form something. To my ear, constituent works better for chemical compounds found in organic matter. Constituent is more accurate in chemistry also: academic.oup.com/nutritionreviews/article/72/8/507/…. Having said that, it wouldn't sound off if component is used in everyday speech. Plus, I offered a better option at the end.
    – ermanen
    Oct 4 at 16:08

I think you're looking for the word component.

A compound is something made up of other things, as is a composition, so those words would far more readily describe green tea than catechin.

I agree that ingredient tends to imply human agency, though that implication is perhaps not absolute.

Component fits the bill nicely, however.

  • Thank you, phoog, for proposing another candidate "component." I was studying if constituent would do. Any thoughts?
    – Pascal
    Oct 4 at 1:06
  • 1
    @Pascal "Constituent" is good. Oct 4 at 2:36
  • @Pascal, yes, constitutent is indeed another option. It has other senses that are not synonymous with component, notably that of a constituent in an electoral district, but in this context the two words are effectively synonyms. I didn't think of it when I wrote this answer and I did not consult a thesaurus; if I had, I probably would have included constituent.
    – phoog
    Oct 4 at 6:44
  • 1
    ... or constituent. Oct 4 at 14:07

Your subtle question is interesting. As a reader, I don't think I would be misled by the phrase, "a naturally occurring ingredient in tea leaves" or the same phrase using a synonym for ingredient like element or component although I do share your reluctance to use ingredient or its synonyms all by themselves. You are obviously a very careful writer. I think you can trust your instincts.

  • Thank you for your words, Falls Church. They are very motivating.
    – Pascal
    Oct 4 at 1:07

Merriam-Webster Unabridged defines ingredient as:

ingredient, noun : something that enters into a compound or is a component part of any combination or mixture : constituent

and gives as an example usage:

[A] formula which will have just about the same ingredients as mother's milk

which in no way implies that mother's milk contains any additives.

As for polyphenols in wine:

Wine's polyphenols come from grapes, mainly from the skins, and because the red-winemaking process involves more extended contact with the grape skins, those wines tend to contain a lot more polyphenols than white wines do.

So polyphenols are a component, or ingredient, of wine that comes from the fruit from which wine is made.

In a similar manner, catechins are indeed an ingredient, or component, of green tea.

  • "which in no way implies that mother's milk contains any additives": but a formula, at least an artificial infant formula will. To my ear, the use of ingredients arises because infant formula is the result of human concoction, and the fact that these ingredients may match the components of mother's milk is secondary.
    – phoog
    Oct 4 at 6:49
  • The phrase "the same ingredients as mother's milk" is perfect example of why not to use "ingredient". The formula has ingredients, mother's milk does not. Problem with dictionaries is that they reflect any and all uses of a word that get traction, including abuses.
    – TimR
    Oct 4 at 10:51
  • @TimR "Abuses" is a tad prescriptivist, but setting aside that objection, the abuse would be yours. Not only does MW not have a definition that matches your usage, but it clarifies the meaning below "ingredient applies to any of the substances which when combined form a particular mixture" and the etymology appears to side with MW. etymonline.com/search?q=ingredient "L. Something that goes into" Now that it has been show the abuse is yours, you might want to abandon "abuse" which has more weight as pejorative than objective classification.
    – J D
    Oct 4 at 12:44
  • 1
    "Ingredient" is what you put. "Goes into" in the "caused to go" sense. There is intention. If not, you just say "component". E.g. ingredients for a recipe. Whether the components of ingredients are themselves ingredients would depend on whether they are intended or just carried over. Also, in frases such as "the ingredients for life" the use is a figurative extension, perhaps slightly humorous. All this, IMHO.
    – Pablo H
    Oct 4 at 14:08
  • 1
    I've heard the phrase "natural ingredient"
    – Barmar
    Oct 4 at 14:49

From MW:


noun in·​gre·​di·​ent in-ˈgrē-dē-ənt Synonyms of ingredient : something that enters into a compound or is a component part of any combination or mixture : constituent
INGREDIENT applies to any of the substances which when combined form a particular mixture. (emphasis mine)

From etymonline.com:

ingredient (n.)

in early use also engredient, early 15c., "something forming part of a mixture," from Latin ingredientem (nominative ingrediens) "that which enters into" (a compound, recipe, etc.), present participle of ingredi "go in, enter," from in- "in" (from PIE root *en "in") + gradi "to step, go" (from PIE root *ghredh- "to walk, go"). Also from early 15c. as an adjective, "forming part of a mixture." (emphasis mine)

There might be some documentation to support the idea that the long-running and historical use of this term requires things to be man-made, but my quick scan doesn't reveal it. That being said, given that a number of people here believe it to be a necessary condition of the definition, it may be that a new sense of the word is developing or is undocumented, and that you share the new sense with others. For the record, I don't have the same association with man-made being part of the "essence" of the word.

Of ingredient, composition, and compound, only the first and last work with 'ingredient' emphasizing it's role as a part, and 'compound' emphasizing it's non-elemental nature. (Chemical compounds are systems of atomic elements.)

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