Using a variable when accessing Eloquent collection

I have an array in my controller called days, which lists the days of the week and I pass it to my view.

I have columns in my DB table such as monday_start, tuesday_start, etc.

Within my view, I can access $product->monday_start like a good boy.

I want to check to see if there's a value in product->XX_start before I do something.

If I want to have a foreach loop for the days of the week and use $day to loop through my table columns, I can't figure out the syntax to append the $day variable onto my Eloquent accessor.

@foreach ($days as $day)
  @if ($product->$day.'_start')
    *do some stuff*
  @endif
@endforeach

I can't figure out how to concatenate the $day variable to '_start'

via Chebli Mohamed