You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Outcome", "Participant", "Intervention"].

Please return the output as a JSON object of the format: {"Participant" : ["patients with COPD", ...], "Intervention" : ["Atenolol", ...], "Outcome" : ["blood pressure", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

A step-by-step introduction to vegetables at the beginning of complementary feeding . The effects of early and repeated exposure . Breastfeeding ( BF ) is associated with willingness to accept vegetables . This may be due to the variety of flavours delivered via breast milk . Some mothers add vegetables to milk during complementary feeding ( CF ) to enhance acceptance . The present study tested a step-by-step exposure to vegetables in milk then rice during CF , on intake and liking of vegetables . Just before CF , enrolled mothers were randomised to an intervention ( IG , n = 18 ; 6 BF ) or control group ( CG , n = 18 ; 6 BF ) . IG infants received 12 daily exposures to vegetable puree added to milk ( days 1-12 ) , then 12 × 2 daily exposures to vegetable puree added to rice at home ( days 13-24 ) . Plain milk and rice were given to CG . Then both received 11 daily exposures to vegetable puree . Intake was weighed and liking rated on days 25-26 and 33-35 after the start of CF in the laboratory , supplemented by the same data recorded at home . Vegetables were rotated daily ( carrots , green beans , spinach , broccoli ) . Intake , liking and pace of eating were greater for IG than CG infants . Intake and liking of carrots were greater than green beans . However , at 6m then 18m follow up , vegetable ( carrot > green beans ) but not group differences were observed . Mothers reported appreciation of the structure and guidance of this systematic approach . Early exposure to vegetables in a step-by-step method could be included in CF guidelines and longer term benefits assessed by extending the exposure period .
{"Intervention": ["vegetables", "vegetables in milk then rice"], "Outcome": ["Intake , liking and pace", "Intake and liking", "than CG infants", "spinach , broccoli"], "Participant": ["mothers", "Breastfeeding ( BF )", "18"]}