Breastfeeding and Non-Alcoholic Liver Disease
by Anne Eglash MD, IBCLC, FABM
NAFLD is becoming an increasingly common reason for liver cancer and cirrhosis (liver failure). Obesity increases the risk of high cholesterol, high triglycerides, diabetes, and NAFLD is another negative manifestation of the metabolic dysfunction associated with obesity. Several studies have shown that breastfeeding reduces the risk of high cholesterol, high triglycerides, diabetes, heart disease and hypertension, mainly because lactation helps to diminish the insulin resistance that occurs during pregnancy. Because the evidence for lactation reducing obesity is mixed, the question is whether lactation reduces NAFLD independent of its effect on obesity.
The data for this research comes from the CARDIA study, which includes 5115 individuals recruited from 4 US cities in 1985-1986. The subjects were followed for up to 25 years to evaluate risks and outcomes of cardiovascular disease. Among these subjects, 844 women had 1 or more births, reported their duration of breastfeeding, and didn’t have other reasons for liver disease. Forty-eight % were black, 52% were white. Thirty –two % of the women breastfed for 0-1 month, 25% for 1-6 months, and 43% for more than 6 months. They each had their livers evaluated by CAT scan for NAFLD 25 years after enrolling in the study.
- Women who breastfed for 1-6 months had significantly less NAFLD as compared to women who nursed for 0-1 month.
- Women who breastfed longer than 6 months had a nearly 50% less risk of NAFLD as compared to women who nursed for 0-6 months.
- At year 25, women with longer lactation duration had lower body mass index, less insulin resistance, and lower triglycerides.
- Although white women had longer lactation duration overall, white women had more NAFLD as compared to black women.
- The researchers found that weight loss was the reason why women who nursed over 6 months had less NAFLD.
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Background & Aims:
Lactation lowers blood glucose and triglycerides, and increases insulin sensitivity. We hypothesized that a longer duration of lactation would be associated with lower prevalence of non-alcoholic fatty liver disease (NAFLD), which is the leading cause of chronic liver disease in the United States.
Participants from the Coronary Artery Risk Development in Young Adults cohort study who delivered ≥ 1 child post-baseline (Y0: 1985–1986), and underwent CT quantification of hepatic steatosis 25 years following cohort entry (Y25: 2010–2011) were included (n = 844). The duration of lactation was summed for all post-baseline births, and NAFLD at Y25 was assessed by central review of CT images and defined by liver attenuation ≤ 40 Hounsfield Units after exclusion of other causes of hepatic steatosis. Unadjusted and multivariable logistic regression analyses were performed using an a priori set of confounding variables; age, race, education, and baseline body mass index.
Of 844 women who delivered after baseline (48% black, 52% white, mean age 49 years at Y25 exam), 32% reported lactation duration of 0 to 1 month, 25% reported >1 to 6 months, 43% reported more than 6 months, while 54 (6%) had NAFLD. Longer lactation duration was inversely associated with NAFLD in unadjusted logistic regression. For women who reported >6 months lactation compared to those reporting 0–1 month, the odds ratio for NAFLD was 0.48 (95% CI 0.25–0.94; p = 0.03) and the association remained after adjustment for confounders (adjusted odds ratio 0.46; 95% CI 0.22–0.97; p = 0.04).
A longer duration of lactation, particularly greater than 6 months, is associated with lower odds of NAFLD in mid-life and may represent a modifiable risk factor for NAFLD.
A longer duration of breastfeeding has been associated with multiple potential health benefits for the mother including reduction in heart disease, diabetes and certain cancers. In this study we found that breastfeeding for longer than 6 months was associated with a lower risk of non-alcoholic fatty liver disease in mid-life.
The authors explain that lactation has several favorable effects on metabolism that are seen at least 25 years after lactation ceases. Lactation increases mother’s metabolic rate, mobilizes fat stores, increases insulin sensitivity, and improves the mother’s cholesterol profile. These improvements in metabolism are responsible for the lower risk of type 2 diabetes, heart disease, high blood pressure, high cholesterol, and NAFLD. Black women in this study were in general at lower risk for NAFLD, and the authors cite research indicating a protective genetic factor.
NAFLD is not only an adult disease, as it is also common among children. In fact, infants born to obese mothers have significantly more fat in their livers by 3 weeks of age as compared to infants born to non-obese mothers. A 2017 study found that adolescents who were exclusively breastfed for over 4 months had significantly less NAFLD as compared to adolescents exclusively breastfed for less than 4 mo. It is possible that the bacterial microbiome of breastfed infants might help to decrease the risk of NAFLD among infants who were born with fat in their livers.
The effect of lactation on NAFLD should yield less liver cancer and cirrhosis for women who breastfed for longer than 6 months, and hopefully lead to less liver disease for breastfed children as well.