To date, there has been no specific data on the relationship between dietary inflammation, maternal diet and SCM, but new research demonstrates a statistical link between micronutrient intake and SCM risk.
The European study of 177 women found diet-associated inflammation increased the odds of developing SCM by 41% and demonstrated a clear association with SCM risk.
“We show for the first-time exploratory evidence that SCM may be associated with a pro-inflammatory diet and women with SCM have lower intakes of several antioxidant and anti-inflammatory nutrients,” the authors say.
“The prevention of SCM is important for both maternal and infant health as SCM may impact the nutritional composition of HM.”
SCM refers to inflammation of the lactating mammary gland, which is asymptomatic but may have adverse effects on human milk (HM) composition and infant growth.
Consumption of refined grains, simple carbohydrates, and red meat correlate with high concentrations of proinflammatory markers. Conversely, diets rich in whole grains, fish, fruit, and green vegetables are associated with lower inflammation.
Women with mastitis are more susceptible to cell damage and display reduced HM antioxidant capacity. Vitamin E and selenium are considered particularly important dietary antioxidants as they reduce production of pro-inflammatory cytokines.
In addition, administration of vitamin E, selenium, zinc, vitamin A, beta-carotene, and copper supplements have been shown to improve recovery from mastitis, the researchers say.
The dietary inflammation index (DII) was used to evaluate diet-associated inflammation of participants in the ATLAS observational study involving six EU countries (Sweden, Spain, Portugal, Norway, Italy, and France).
Female recruits were in the last trimester of pregnancy and maternal demographics, anthropometry, and medical history were collected by trained staff.
Milk samples were obtained using an electric breast pump and from the same breast in each case for the entire study. Samples were analysed for sodium (Na) and potassium (K).
SCM was assessed in early lactation and at approximately 0 to three days, 17 days, and 30 days postpartum. SCM incidence was defined as a sodium potassium ratio (Na:K) in HM higher than 0.6, at any of the three visits.
Two 3-day food diaries were collected (at visit two and three) and collated into daily nutrient intake using the Nutrilog software and French food composition table. Finally, DII scores were calculated based on peer-reviewed articles and set criteria.
SCM was significantly associated with DII and dietary intake of micronutrients, the authors report. Demographically, France (42%) and Portugal (43%) had the largest proportion of women with the highest DII scores.
Results showed that women with SCM consumed below average levels of carbohydrates, fibre and nutrients that contribute to the normal function of the immune system (selenium, vitamin C, vitamin E, manganese), compared to women without SCM.
Selenium has demonstrated antibacterial activity that reduces mastitis risk, while studies on a dairy herd revealed lower incidence of chronic clinical mastitis following a multimineral injection with selenium, copper, zinc, and manganese, according to the authors.
Lower magnesium, phosphorus, potassium, calcium, β‐carotene, and B‐vitamins (riboflavin, vitamin B6, folate, and vitamin B12) were also observed in subjects with SCM.
Data supports previous findings on the increased risk of SCM with low intake of vitamin E and C. Vitamin E has shown beneficial activity in lowering HM Na:K ratios and regulating specific cytokines at three months postpartum, while vitamin C supports vitamin E regeneration and inhibits growth of mastitis-promoting bacteria.
“It could be hypothesised that the imbalance in the intake of anti‐inflammatory and pro‐inflammatory foods may be triggering oxidative stress that, in turn, may have a role to play in the etiology of SCM,” the authors’ comment.
Furthermore, the absence of the four vitamin B compounds could impact immune responses, including B and T lymphocyte maturation and function.
The researchers were not able to establish causality between diet and SCM, and while poor diet may have increased the risk of SCM, the condition itself may have changed nutritional requirements. In addition, data on women with elevated Na:K ratios was not followed up to determine the proportion who developed mastitis and the impact on breastfeeding outcomes.
The authors therefore conclude: “The role of anti‐inflammatory nutrients in reducing the risk for SCM should be evaluated in future studies with a larger sample size and include breastfeeding outcomes.”
Published online, November 8, 2022: http://doi.org/10.3390/nu14224719
‘The Dietary Inflammatory Index Is Associated with Subclinical Mastitis in Lactating European Women’
Authors: Myriam C. Afeiche, Alison Iroz, Frank Thielecke, Antonio C. De Castro, Gregory Lefebvre, Colleen F. Draper, Cecilia Martínez‐Costa, Kirsti Haaland, Giovanna Marchini, Massimo Agosti, Magnus Domellöf, Thameur Rakza, Maria José Costeira, Mireille Vanpee, Claude Billeaud, Jean‐Charles Picaud, Daryl Lim Kah Hian, Guimei Liu, Nitin Shivappa, James R. Hébert and Tinu M. Samuel