This study aims to compare immunologic parameters of 60 patients who are 1-28 days-aged, below 1500-gram body weight, born before 32 weeks of gestational age and fed with eoprotin or olive-oil fortified breast milk. Cases will receive same amount of calorie intake either with eoprotin or olive oil fortified-breast milk. If investigators identify that olive oil doesn't increase proinflammatory cytokines and grant enough weight gain in premature infants at the end of the study, investigators will suggest olive oil to replace eoprotin which is a very costly breast milk-fortifier.

Low birth weight infants are premature infants that born with birth weight less than 1500 g. Because these infants have low birth weight, weight gain can be increased by fortifying breast milk after post-natal 7. day. Breast milk fortifiers might be preferred for very low birth weight or extremely low birth weight infants (infants with <1000 g birth weight infants) for faster weight gain. It does not increase risk of necrotizing enterocolitis or infection; and it has lower incidences of necrotizing enterocolitis and sepsis comparing to formula. Breast milk is usually fortified with 100 cc/kg/day enteral feeding (1,2,3,4). Even though many centers use olive oil to fortify breast milk for many years; there is no study to evaluate its scientific value. Hence it has been known that olive oil based parenteral nutrition solutions are well-tolerated by premature infants, are immunologically more neutral, does not increase proinflammatory cytokines; olive oil is the only fat consumed in its natural form and has antimicrobial and cytotoxic effects, lowers serum cholesterol concentration by decreasing cholesterol absorption, has protective measures against cardiovascular diseases due to antioxidant effects of ingredients such as mono- and poly-unsaturated fatty acids, phenolic substances, tocopherols and carotenoids; olive oil has antioxidant, cell renewal and anti- carcinogenic features because of containing squalene which is precursor of steroid synthesis and help digestion by increasing digestive juice by major pigments such as chlorophyll, pheophytin and chlorophyll (5).

In previous studies; it has been shown that nutritional support with parenteral olive oil emulsion has better plasma lipid content similarities to breast milk, lower proinflammatory cytokine synthesis, lower lipid peroxidation product levels, stronger T-cell response, higher E vitamin levels; and thus lower risk of nosocomial infections, SIRS (systemic inflammatory response syndrome), BPD (bronchopulmonary dysplasia), NEC (necrotizing enterocolitis), PVL (periventricular leukomalacia), ROP (retinopathy of prematurity) and cardiovascular diseases and positive impact on glucose metabolism. Participants hypothesize that oral olive oil intake will have similar effects (6).

Investigators aims to compare post-nutritional immunologic parameters of 1-28 day-aged 60 infants with <1500 g birth weight and < 32 weeks of gestational age who were fed with maternal milk that is fortified with eoprotin and olive oil and diagnosed and followed-up in Neonatal Intensive Care Unit of Pediatrics Department of Medicine Faculty of Yüzüncü Yıl University.

This study will be conducted on 60 patients who are 1-28 days-aged, below 1500-gram body weight, born before 32 weeks of gestational age and diagnosed and followed in Neonatal Unit of Pediatrics Department of Medicine Faculty of Yüzüncü Yıl University. For 45 days, 30 patients will receive eoprotin as breast milk fortifier while another 30 patients will receive olive oil, then 3 cc of blood will be taken from all patients at 0, 15., 30. and 45. days into biochemistry vials and will be stored at -80 C after centrifuge. At the end of the study, vials will be thawed in room temperature and serum TNF-alpha, IL-1 Beta, IL-6, IL-8, IL-10 levels will be analyzed with ELISA method by BIO-Tec ELx800 Absorbance Reader device and lipid profiles (LDL, HDL, Total cholesterol and triglyceride) and levels will be analyzed with spectrophotometric method by Architect ci16200; then these parameters will be compared with each other.

After feeding with olive oil infants will have received same amount of calorie with infants who will receive eoprotin-fortified breast milk. At the end of study, if participants identify that olive oil doesn't increase proinflammatory cytokines and provide enough weight gain in premature infants, investigators will suggest olive oil to replace eoprotin which is a very costly breast milk-fortifier. Investigators believe this situation will contribute to both country and family budgets.

Inclusion Criteria:

• Infants with <1500 g birth weight
• Infants with< 32 weeks of gestational age
• Infants who will be fed with maternal milk that is fortified with eoprotin and olive oil

Exclusion Criteria:

• Critical ill patients
• Evident severe congenital malformation
• Intolerance of feeding
• Evident gastrointestinal malformation