tumetai zyuusu bakari nomu to, karada ga hierukoto ga arimasu.

Japanese is normally written without spaces.

So the standard writing would be:

冷たいジュースばかり飲むと、体が冷えることがあります。

The spaces here are just a learning aid to make the sentence parts easier to see.

Because 冷たい is an い-adjective.

• い-adjectives go directly before a noun
  
  • 冷たいジュース = cold juice
• な-adjectives need な before a noun
  
  • for example, 静かな部屋 = a quiet room

So 冷たいジュース is correct, and 冷たいなジュース would be wrong.

Here, ばかり means something like:

• only
• nothing but
• mostly

So 冷たいジュースばかり飲む means that someone drinks only or mostly cold juice.

A small nuance:

• It can sound like a repeated habit
• It can also carry a feeling of too much of that one thing

So the sentence is not just describing a random one-time action. It suggests a pattern or habit.

It can suggest both, depending on context.

Most basically, it means:

• you drink only/mostly cold juice

But ばかり often has a nuance of:

• you keep doing that
• you do that more than is ideal

So in this sentence, it sounds a bit like a warning about a habit: drinking cold juice all the time.

Because inside a sentence like this, Japanese usually uses the plain form in subordinate clauses and grammar patterns.

Here:

• 飲む comes before と
• 冷える comes before ことがあります

Both of those normally take the plain form.

The sentence is still polite overall because it ends with あります.

So this is completely normal:

• 冷たいジュースばかり飲むと、体が冷えることがあります。

Using 飲みますと or 冷えますことがあります here would sound unnatural.

Here, と is a conditional, meaning if or when.

So:

• 飲むと = if you drink / when you drink

But this と is often used for:

• general truths
• natural consequences
• habitual results

That fits this sentence well, because it is saying a general result:

• if you keep drinking only cold juice, your body may get chilled

This と is less about a personal decision and more about a predictable result.

Because 体 is the subject of 冷える.

• 冷える = to get cold / to become chilled
• What gets cold? 体
• So: 体が冷える

Japanese often describes bodily conditions this way, with the body or body part as the subject.

English often says:

• you get cold

Japanese often says something closer to:

• your body gets cold
• your stomach gets cold
• your hands get cold

So 体が is very natural.

Because 冷える and 冷やす are different kinds of verbs.

• 冷える = something gets cold, becomes chilled
  
  • intransitive
• 冷やす = to cool or chill something
  
  • transitive

In this sentence, the body is becoming chilled, not actively being chilled by a person as a direct object.

So:

• 体が冷える = the body gets cold

If you used 冷やす, it would mean someone is cooling something:

• 体を冷やす = to cool the body

That is a different structure and meaning.

Because there are really two layers in that part of the sentence.

First layer:

• 体が冷える = the body gets cold

Second layer:

• 体が冷えること = the event of the body getting cold
• 体が冷えることがあります = there are times when the body gets cold

So the two が do different jobs:

• the first が marks 体 as the subject of 冷える
• the second が marks 体が冷えること as the subject of あります

This is very common in Japanese when a whole clause is turned into a noun-like phrase with こと.

〜ことがあります means:

• there are times when ...
• ... sometimes happens
• ... may happen

So:

• 体が冷えることがあります = your body may get chilled / sometimes your body gets chilled

The こと turns the verb phrase into an event or occurrence:

• 冷える = to get cold
• 冷えること = the act/event of getting cold

Then あります literally means that such an event exists.

This pattern makes the statement softer and less absolute than simply saying:

• 体が冷えます = your body gets cold

With ことがあります, the meaning is more like:

• this can happen
• this happens sometimes
• this is a possible result