Breastfeeding and Mitochondrial DNA in Adolescents
by Anne Eglash MD, IBCLC, FABM
Mitochondria are little energy factories that exist in every living cell in the human body and produce particles of energy, called ATP. ATP for cellular function is analogous to gas (or an electric charge) for our cars; it is required to keep us going. Healthy mitochondria have more mitochondrial DNA (mtDNA), while dysfunctional mitochondria have less DNA. Studies have shown that when a person has less mtDNA, they are at higher risk for health problems, particularly diabetes, hypertension, heart disease and metabolic syndrome.
This study was done among 303 adolescents taking part in the Flemish Environment and Health Study, which is a human biomonitoring network in Belgium since 2002, measuring the relationship between environmental conditions and human health. Duration of breastfeeding was recorded for these children, and 14-15 years later, their mtDNA was measured. They took into account several other life factors such as gestational age, exposure to smoking, maternal age, maternal alcohol consumption during pregnancy, socioeconomic status, BMI, sex, and season. Nearly all (99.3%) of the teens were Caucasian.
They found that longer breastfeeding and more exclusive breastfeeding were associated with greater mtDNA during adolescence. This was more evident for boys than girls. Breastfeeding for 1-10 weeks, 11-20 weeks, and greater than 20 weeks was associated with 16%, 23.5%, and 31.5% increased mtDNA respectively.
The authors state that this mechanism may explain the life-long metabolic differences that are seen in individuals who are breastfed, and that this evidence contributes to the 'Developmental Origins of Health and Disease' hypothesis, which states that health or diseases may find their origin in early life.
- The greater the visceral fat (belly fat), the lower the mtDNA.
- Adults with a higher BMI have less mtDNA.
- Lower mtDNA is seen in people who are insulin-resistant, and therefore at higher risk of becoming diabetic.
- Increased mtDNA plays an important role in brain development.
- Age-related neurodegenerative diseases such as Parkinson’s disease, are associated with less mtDNA.
See the Answer
Nutrition during early childhood is linked to metabolic programming. We hypothesized that breastfeeding has long-term consequences on the energy metabolism exemplified by mitochondrial DNA (mtDNA). As part of the third cycle of the Flemish Environment and Health Study (FLEHSIII) cohort, 303 adolescents aged 14–15 years were included. We associated breastfeeding and blood mtDNA content 14–15 years later while adjusting for confounding variables. Compared with nonbreastfed adolescents, mtDNA content was 23.1% (95%CI: 4.4–45.2; p = 0.013) higher in breastfed adolescents. Being breastfed for 1–10 weeks, 11–20 weeks, and >20 weeks, was associated with a higher mtDNA content of respectively 16.0% (95%CI: −7.1–44.9; p = 0.191), 23.5% (95%CI: 0.8–51.3; p = 0.042), and 31.5% (95%CI: 4.3–65.7; p = 0.021). Our study showed a positive association between breastfeeding and mtDNA content in adolescents which gradually increased with longer periods of breastfeeding. Higher mtDNA content may be an underlying mechanism of the beneficial effects of breastfeeding on children’s metabolism.
It is exciting to have research findings that explain the physiologic effects of breastfeeding. For about a quarter century, our breastfeeding research has been largely epidemiologic. For example, many studies done in large populations show less stroke, heart disease, breast cancer, metabolic syndrome, diabetes in mothers who have breastfed, and lower rates of infection, inflammation, cancer, and obesity, among children who are breastfed. But the naysayers focus on the confounders to explain these relationships, such as BMI, socioeconomic status, higher education, healthier diet in breastfeeding families, etc.
Hopefully our new decade will usher in more physiologic research, such as today’s study, that provide the biologic plausibility to explain the consistent associations between breastfeeding and disease.