What is the version of the following sentence with correct punctuation?

131 people in the latter group were diagnosed with Alzheimers disease during the following four years It turned out however that in the 20 who had the lowest intake of niacin on average 125 mg a day the incidence of Alzheimers disease was more than three times as high compared to the ones with the highest intake 224 mg a day or more
131 people in the latter group were diagnosed with Alzheimer's disease during the following four years. It turned out, however, that in the 20% who had the lowest intake of niacin (on average 12.5 mg. a day), the incidence of Alzheimer's disease was more than three times as high compared to the ones with the highest intake (22.4 mg. a day or more).