These verbs all have the same meaning. The difference is in their grammatical structure:

LET + PERSON/THING + VERB (base form - without "to")

Examples:

I don't let my kids watch violent movies.

Mary's father won't let her adopt a puppy because he's allergic to dogs.

Our boss doesn't let us eat lunch at our desks; we have to eat in the cafeteria.

Oops! I wasn't paying attention while cooking, and I let the food burn.

Don't let the advertising expenses surpass $1000.

The simple past tense of let is also let; there is no change!

The verbs allow and permit are more formal ways to say "let." However, with allow and permit, we use to + verb:

I don't allow my kids to watch violent movies.

Our boss doesn't permit us to eat lunch at our desks.

Permit is the most formal, let is the least formal, and allow is in the middle.

With permit and allow, we can also say that something is or is not permitted/allowed:

Smoking is not allowed.

Employees are allowed to take a one-hour lunch break.

Passengers are not permitted to use cell phones during takeoff.

With a tourist visa, you are permitted to stay in the country for 90 days.

Benefits of Guava

Scurvy

Guava can outdo many other fruits, including orange and other citrus fruits, in terms of its concentration of vitaminC. Adeficiency of vitaminC can cause scurvy, and proper intake of vitaminC is the only known remedy for that dangerous disease. In fact, guavas contain 5X more vitaminC than oranges, which are often heralded as the absolute best source of that beneficial vitamin.