Η βιταμίνη C με βοηθάει όταν έχω συνάχι.

Η is the definite article in Greek, here meaning the.
So η βιταμίνη C means vitamin C / the vitamin C.

Greek uses articles more often than English does, and nouns normally appear with an article when talking about something specific or as a general known thing.

• η = feminine singular nominative the
• βιταμίνη is a feminine noun, so the article must match it

That is why you get η βιταμίνη C.

In Greek, every noun has a grammatical gender: masculine, feminine, or neuter.
Βιταμίνη happens to be feminine, so it takes feminine forms like:

• η βιταμίνη = the vitamin
• τη βιταμίνη = the vitamin (object form)

This gender is grammatical, not biological. English speakers often want a logical reason, but usually gender just has to be learned along with the noun.

A good habit is to learn new nouns together with their article:

• η βιταμίνη
• το συνάχι
• ο φίλος

Με here means me.

In the sentence Η βιταμίνη C με βοηθάει, the verb βοηθάει means helps, and με is the direct object:

• Η βιταμίνη C = vitamin C
• με = me
• βοηθάει = helps

So literally: Vitamin C helps me.

This με is a weak pronoun, often called a clitic. Greek usually prefers this short form instead of a full stressed pronoun here.

Because με is the normal unstressed object pronoun used with verbs.

Compare:

• Η βιταμίνη C με βοηθάει. = Vitamin C helps me.
• Η βιταμίνη C βοηθάει εμένα, όχι εσένα. = Vitamin C helps me, not you.

So:

• με = normal neutral me
• εμένα = stressed/emphatic me

In your sentence, there is no special emphasis, so με is the natural choice.

Because the subject is η βιταμίνη C, which is third person singular: it.

The verb must agree with the subject:

• εγώ βοηθάω / βοηθώ = I help
• εσύ βοηθάς = you help
• αυτός/αυτή/αυτό βοηθάει / βοηθά = he/she/it helps

So in Η βιταμίνη C με βοηθάει, the subject is vitamin C, not I.
That is why the verb is helps, not help or I help.

Yes. In Modern Greek, βοηθάει and βοηθά are both common and mean the same thing here:

• Η βιταμίνη C με βοηθάει
• Η βιταμίνη C με βοηθά

Both mean Vitamin C helps me.

Βοηθάει may sound a little fuller or more conversational to some speakers, while βοηθά is also completely standard. Learners should recognize both.

Because Greek often drops subject pronouns when they are not needed.

In English, you must say:

• It helps me

But in Greek, the verb ending already shows the person and number, and the noun subject is already present:

• Η βιταμίνη C με βοηθάει

Since η βιταμίνη C is already the subject, there is no need to add a separate word for it.

Όταν means when.

It introduces a time clause:

• όταν έχω συνάχι = when I have a cold

It is used very much like English when, but Greek usually keeps the verb in a normal finite form after it.

Examples:

• Όταν είμαι κουρασμένος, κοιμάμαι νωρίς. = When I am tired, I sleep early.
• Όταν έχω χρόνο, διαβάζω. = When I have time, I read.

Greek usually leaves out subject pronouns unless they are needed for emphasis or contrast.

So:

• έχω already means I have
• εγώ έχω means I have, but with extra emphasis, like I have

In your sentence, there is no need to emphasize I, so Greek naturally says:

• όταν έχω συνάχι

not usually

• όταν εγώ έχω συνάχι

Greek often omits the article with certain nouns when speaking in a general or indefinite way, especially with expressions of having an illness or condition.

So:

• έχω συνάχι = I have a cold
• έχω πυρετό = I have a fever

This is similar to English, where we also often say I have a cold without making it especially specific.

You may also hear other patterns in Greek depending on the noun and context, but έχω συνάχι is completely natural.

Συνάχι usually refers to a cold, especially the symptoms of a runny or blocked nose. In everyday English, translating it as a cold is often fine.

However, it can sometimes feel a bit narrower than κρυολόγημα, which is another common word for cold in the sense of the illness.

Very roughly:

• συνάχι = cold / sniffles / nasal cold
• κρυολόγημα = cold, the illness more generally

In many everyday situations, though, learners can understand συνάχι simply as a cold.

Yes. Greek word order is more flexible than English word order.

Your sentence is:

• Η βιταμίνη C με βοηθάει όταν έχω συνάχι.

But you could also say:

• Με βοηθάει η βιταμίνη C όταν έχω συνάχι.
• Όταν έχω συνάχι, με βοηθάει η βιταμίνη C.

These versions still mean essentially the same thing, but the emphasis shifts slightly.

The version you were given is a very straightforward, neutral order: subject + object pronoun + verb + when-clause

A rough pronunciation guide is:

ee vee-tah-MEE-nee si me vo-ee-THA-ee OH-tan EH-ho sy-NA-hi

A few notes:

• η sounds like ee
• β sounds like v
• θ sounds like th in think
• χ sounds like the German Bach or Scottish loch
• συνάχι is stressed on -νά-
• βιταμίνη is stressed on -μί-
• όταν is stressed on the first syllable

Also, the C in βιταμίνη C is usually pronounced like the English letter name C, i.e. σί in Greek.

The structure is:

• Η βιταμίνη C = subject
• με = object pronoun
• βοηθάει = verb
• όταν έχω συνάχι = time clause

So literally:

Vitamin C me helps when I have a cold

Natural English:

Vitamin C helps me when I have a cold

Seeing it in chunks can make it easier to process:

• Η βιταμίνη C
• με βοηθάει
• όταν έχω συνάχι

Usually it sounds like a general/repeated situation:

Vitamin C helps me when I have a cold.

In other words, whenever that situation happens, this is generally true.

Greek often uses the present tense for this kind of general statement, just like English does here.

So the sentence does not necessarily mean:

• right now I have a cold

It more naturally means:

• whenever I get a cold, vitamin C helps me