Additionally, reverse causation could be at play, where people already at risk for various diseases, including heart disease, might purposely quit eating chocolate because of this. Myint tells me that this is less of a possibility. But there may be people with particular risk profile for CVD, and therefore reverse causation cannot be completely ruled out.” Still he says, it can’t explain the whole effect. There are some other drawbacks, like the fact that people only reported on their diets in the initial assessment, and that the study only looked at middle-aged and older people.

заранее спасибо )

Myint tells me that this is less of a possibility:
Myint-я так понимаю, что это какой-то научный дяденька
tells me that-сообщает, говорит мне, что
less of a possibility-меньшая вероятность

But there may be people with particular risk profile for CVD, and therefore reverse causation cannot be completely ruled out:
But there may be people-но могут быть люди
with particular risk profile for –предрасположенные к
CVD – google it!!
and therefore -и, следовательно
cannot be completely ruled out-не может быть полностью исключено

Still he says, it can’t explain the whole effect:
Still -тем не менее
he says-он продолжает вещать (это литературный перевод фразы 
it can’t explain the whole effect-это полностью не может объяснить, этим нельзя полностью объяснить [наблюдаемый] эффект

There are some other drawbacks, like the fact that people only reported on their diets in the initial assessment, and that the study only looked at middle-aged and older people:
There are some other drawbacks-есть и другие недостатки (препятствия)
like the fact that-как, например, тот факт, что
people only reported on their diets-люди (или пациенты) сообщили только о своих диетических предпочтениях
in the initial assessment-во время первоначального опроса, осмотра, оценки и т.п.
and that the study only looked at middle-aged and older people -и что в исследовании принимали участие только люди среднего и более зрелого возраста (или старше, чем среднего)

P.S. вы бы лучше тему создали про reverse causation, всяко было бы интереснее.
вот определение из гугла:
reverse causation-a situation in which one variable is said to cause another variable, when in reality the reverse is true.

и парочка примеров с форумов на тему:

Am I bored because I'm reading this thread,
or am I reading this thread because I'm bored?

do you drive a scooter because you're fat,
or are you fat because you're on a scooter?