The relationship between stress response, milk production, metabolic health factors and micronutrient status in lactating women
Open Access
- Author:
- Soucy, Elizabeth
- Area of Honors:
- Nutritional Sciences
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Alison D Gernand, Thesis Supervisor
Alison D Gernand, Thesis Honors Advisor
Penny Margaret Kris-Etherton, Faculty Reader - Keywords:
- lactation
cortisol
cortisone
milk production
metabolic health
micronutrient status - Abstract:
- Low milk production and delayed onset of lactogenesis is related to early cessation of breastfeeding. Breastfeeding has many health benefits for the mother, including a decreased risk for cardiometabolic disorders, like diabetes, while also benefiting the health of the infant. Cortisol—a key stress marker—increases abundantly towards the end of gestation and diffuses across the mammary epithelia during lactation. Limited research has found a relationship between poor, metabolic health leading to higher cortisol, and separately, higher cortisol leading to poor maternal micronutrient status. This thesis aimed to examine the interrelationships between stress and milk production, metabolic health, and micronutrients. We conducted a sub-study of stress and lactation from a parent study of low, moderate, and adequate milk production. The amount of milk produced by each mother (n=61) was categorized: very low milk production (<300 mL/day, n=23), moderate milk production (>300 mL >700 mL/day, n=20) and adequate milk production (>700 mL/day, n=18). We measured stress hormones (cortisol and cortisone, in serum and milk) and micronutrient biomarkers (ferritin, folate and 25-hydroxyvitmain D, in serum) and we used existing data on metabolic health (body mass index, glucose and triglycerides) from the parent study. The stress response was different across milk production groups for serum cortisone (p<0.01), milk cortisol (p=0.04), and milk cortisone (p<0.01)—with the highest concentration of stress hormones in adequate milk producing mothers and the lowest concentration of stress hormones in moderate milk producing mothers. Mothers with low milk production had similar stress hormone concentration to adequate milk producing mothers. In all participants, body mass index was negatively associated with serum cortisol (β-0.13 [95% CI: -0.27, -0.005] nm/mL per kg/m2) and plasma glucose was positively associated with milk cortisone (β1.45 [95% CI: 0.55, 2.34] nm/mL per mg/dL). Stress markers were not related to iron, folate, or vitamin D biomarkers (all p>0.05). In summary, we found that stress response was different across milk production groups, but not in the expected pattern. Stress and metabolic health factors were also associated, but the relationship was inverse for BMI and serum cortisol, contrary to our hypothesis. Future studies, designed specifically to examine stress markers in lactating mothers—should be conducted to further investigate interactions between stress lactation outcomes and nutritional status.