Yes " public distribution system " can ensure better food security for people because: 1 from the scheme name it's self we can say.....public distribution this says the food will be given to the public(not all the public or people , only who are recognised by government as poverty) they will be given some amount of rice,pulses,dal whatever it might be but for very low prise.
2 the government make sure that every poverty men or women or family(only people who have some special card..I guess "ration card") get the monthly stuff...
3 as we know that PDS is a government scheme,they make sure that the stuff what ever they give is purely edible and safe to eat.
HOPEFULLY THIS MIGHT BE HELPFUL TO YOU . IF YOU FEEL IT'S WORTH . GIVE ME AS BEST.