What has been said about olive oil:

((And a tree (olive) that springs forth from Mount Sinai, that grows oil, and (it is a) relish for the eaters.))

[Al-Mu’minun, 20]

 Allah the Almighty says in another Ayah:

((Lit from a blessed tree, an olive, neither of the east (i.e. neither it gets sun-rays only in the morning) nor of the west (i.e. nor it gets sun-rays only in the afternoon, but it is exposed to the sun all day long).))

[An-Nur, 35]

 Scientists were puzzled with regard to these two Ayahs in which the olive tree was described as a blessed tree, and whose oil is considered as the most preferable oil to be used in man’s life.
 Due to their lack of information and experience in regard of this tree, scientists used to think that the fat in this oil is harmful, however the noble Quran and Sunnah said the otherwise, for the prophet PBUH said in Sahih Hadith:

((Eat of its oil and use it (the olives), for indeed it is from a blessed tree.))

[Tirmizi in his Sunan]

 And in another Hadith the prophet PBUH said:

((Cook with oil and use it (the olives), for indeed it is from a blessed tree.))

[Ibn Majah in his Sunan]

 According to the most recent researches which were published a few years ago, the olive oil is a fuel to mankind by all means, for every one gram of olive oil contains 8 calories which is considered as the perfect source of energy for man.
 According to nutrition scientists, the fatty acids are of two types: saturated and unsaturated.
 The saturated fatty substance stays in blood stream and clings to the artery walls and it accumulates causing narrowing of the arteries and hardening to their walls, and consequently this will cause heart diseases.
 Hence, saturated fatty acids are harmful to the human being whereas the unsaturated fatty acids become neutral when they devour the other fatty substances,
According to scientists, the benefits of olive oil are mostly due to the very high concentration of monounsaturated fatty acids and anti-oxidative substances which are good for the body, and they prevent fatty deposits from clinging to the artery walls unlike the saturated fatty acids which exist in most kinds of animal fat.
 The saturated animal fats cause arteriosclerosis and they cause heart diseases, and for that very reason, it is recommended by doctors that man should take at least one spoon of olive oil daily in order to prevent the occurrence of arteriosclerosis and to treat it at the same time.
 Olive oil is considered as a (natural) laxative, a sedative and it works as "antihelmintic," or anti-worm.
 Most animal fats hurt the stomach unlike olive oil which is considered as a restorative substance for the gum and a softener for the skin.
 But mostly, what makes one wonders, is that it took the doctors in general and cardiologists in particular long time to find out the benefits of olive oil to the arteries, for olive oil softens their walls, prevents arteriosclerosis, and since it contains monounsaturated fatty acid, it doesn’t cling to the artery walls and thus it doesn’t cause narrowing of the arteries nor does it hardens artery walls, and this is the meaning of Allah’s Ayah:

((And a tree (olive) that springs forth from Mount Sinai, that grows oil, and (it is a) relish for the eaters.))

[Al-Mu’minun, 20]

 And in another Ayah Allah says:

((Lit from a blessed tree, an olive, neither of the east (i.e. neither it gets sun-rays only in the morning) nor of the west (i.e. nor it gets sun-rays only in the afternoon, but it is exposed to the sun all day long).))

[An-Nur, 35]

 And in a third Ayah:

((By the fig, and the olive, By Mount Sinai, And by this city of security (Makkah),))

[At-Tin, 1-3]

 In the Sahih Hadith, the prophet PBUH said:

((Eat of its oil and use it (the olives), for indeed it is from a blessed tree.))

[Tirmizi in his Sunan]

 And in another Hadith He said:

((Cook with oil and use it (the olives), for indeed it is from a blessed tree.))

[Ibn Majah in his Sunan]

 The more advanced science is, the much closer to Quran and Sunnah it will be, and on the other hand, the further to Quran and Sunnah science is, the more backward it will be and that will mark its imperfection and inclining from the truth which was brought by Quran.