Maternal diet provides the resources for the production of breast milk; most of the constituents are created de novo by the mother and are specific to the unique needs of the human infant.1–9 Regardless of the tremendous variation in maternal diets across cultures, races, and ethnicities, the content of human milk is remarkably similar. There has been only limited study of how the volume and nutrient content of human milk is affected by dietary intake and maternal nutritional status, however, it appears that only deficiency states for selected nutrients and/or prolonged inadequate caloric intake appear to cause significant changes in breast milk quality. This chapter includes information that the obstetrician/gynecologist can use to counsel a breastfeeding woman about her dietary intake and interest in returning to prepregnancy weight. Dieting during pregnancy as well as special dietary concerns are discussed.
Dietary Reference Intakes (DRIs) for Lactation From the Institute of Medicine
DRIs FOR LACTATION
DRIs are the levels of intake of essential nutrients considered adequate to meet or exceed known nutritional needs of practically all healthy people.10 Table 1 shows the DRIs developed by the Institute of Medicine (IOM) for breastfeeding women including good food sources and Upper Tolerable Limits that should be avoided. We will only discuss the nutrients typically lacking in the diets of US women of reproductive age. The obstetrician/gynecologist can use the DRI values along with the Dietary Guidelines for Americans (http://www.health.gov/dietaryguidelines) to counsel a woman to support lactation while preventing obesity and selected chronic disease for both herself and her infant.
The DRIs for nutrients increased during lactation are: energy, protein, carbohydrate, water, dietary fiber, linoleic acid, and select vitamins and minerals.10 A woman surfing the Internet will find differing answers to the question “how many extra calories do I need for lactation.” The answer is somewhere between 500 and 670 kcal/d during the first 6 months of lactation to 300 to 400 kcal/d in the subsequent months reflecting the variation in rates of milk production and nutritional status of the woman. The energy content of the milk (644 to 740 kcal/L) plus the energy required to produce the milk (625 to 850 kcal/L) is the energy costs of producing 750 g of breast milk per day. In well-nourished women, this is partially met by energy mobilization from fat tissue stored during pregnancy.11 The energy needs for a lactating woman can be calculated at: http://fnic.nal.usda.gov/fnic/interactiveDRI/.
For some nutrients like protein, fat, carbohydrates, and most vitamins and minerals, maternal nutrition has little or no effect on the nutrients in human milk as the woman, even with limited intake, can produce adequate amounts from body stores. Many of the vitamins and minerals are supplied in the typical woman’s diet and despite limited evidence to support the practice, it is common for lactating women in the United States to take a multiple vitamin mineral supplement. For a few nutrients, including vitamins A, B6, B12, and D, iodine and types of lipids consumed such as long chain polyunsaturated fatty acids (LC-PUFA), the quality of human milk can be affected by low maternal intake.2–8 Although the total fluid requirement (water in food, beverages, and as drinking water) is increased from 2.7 to 3.8 L in lactation, additional fluid intake does not increase milk production,6 and the mother’s thirst usually satisfies her fluid requirements. As the calorie needs for lactation are increased only a small amount, women should be counseled to limit calorie-containing beverages such as soft drinks, sweet teas, and coffees. Adult women routinely consume caffeinated beverages, alcohol, and herbal teas. There is conflicting information about the risks and benefits of these food behaviors to the woman and the infant. See chapter on medications and drugs in mother’s milk.
Dietary Guidelines for Lactating Women
The 2010 Dietary Guidelines for Americans (http://www.choosemyplate.gov/) and ChooseMyPlate(http://www.cdc.gov/breastfeeding/) include recommendations and access to personalizing a plan with daily food group targets that meet known nutrient needs within their calorie allowance.10 Updated guidelines will be released in 2015. The amount of nutriments needed for supplementation during lactation is inversely proportional to the amount of complementary food consumed by the infant. Although all world and national health organizations recommend exclusive breastfeeding for the first 6 months, with the addition of complementary foods slowly between 6 and 12 months, and continue breastfeeding through 12 months and beyond, not all women are able to follow the recommendation. The supplements for lactation then, should be reduced appropriately. If for example, only 20% of the food consumed by the infant is breast milk, then only 20% of the supplements for lactation are needed. A consumer-friendly dietary analysis programs available, such a Supertracker.gov can be used to assess the diet for nutrient adequacy before adding dietary supplements. Face-to-face nutritional counseling from a Registered Dietitian Nutritionist (RDN) would benefit women with special concerns including but not limited to iron deficiency anemia, food allergies or sensitivities, history of bariatric surgery, interest in quickly returning to prepregnancy weight, a desire to follow dietary patterns that restrict foods that typically provide important nutrients to the American diet, such as vegan or wheat or gluten free or with folk beliefs such as a need to avoid spicy foods, beans, or cruciferous vegetables purported to cause infant gassiness or colic. RDNs may be found at Women Infant Children programs and/or health departments; some offices of the Cooperative Extension Service (http://www.csrees.usda.gov/Extension); and through the Academy of Nutrition and Dietetics (http://www.eatright.org) and provider listings of insurance companies. Additional information for lactating women can be found at: http://kidshealth.org/parent/growth/feeding/breastfeed_eating.html.
DIETING DURING LACTATION
Over 30% of US women of reproductive age are obese [body mass index (BMI)>30] with 10% morbidly obese (BMI>40). The average weight retention at 6 months’ postpartum has been 12 pounds, with 50% of women retaining >10 and 25% >20 pounds. Black women are at higher risk for retaining more weight than white or Hispanic women, as are women with more gestational weight gain and low income.9 Although women are counseled on appropriate weight gain during pregnancy (http://resources.iom.edu/Pregnancy/WhatToGain.html), less emphasis is given to postpartum weight loss even though researchers have linked postpartum weight retention with increased risk for chronic disease. American College of Obstetricians and Gynecologists1 has recommended breastfeeding, particularly by underserved women, to promote postpartum weight loss and lower the risks of childhood obesity, postpartum depression, diabetes, and cardiovascular disease. Women interested in postpartum weight loss are typically advised to breastfeed. It appears, however, that breastfeeding women vary in the way they lose weight, with some losing weight in the early weeks of breastfeeding, others later; some not until the infant is weaned. A few even gain weight. In early lactation, weight loss appears to occur at a slow rate without conscious dieting.11 Later in lactation, physiological priorities change and, in general, women would need to breastfeed for a substantial period to reduce body fat. Although it has been demonstrated that women can restrict energy intake or increase exercise without an adverse effect on milk volume or composition,12 there is limited evidence to recommend any specific approach such as a carbohydrate-restricted or ketogenic diet. One report from a small and short term intervention found that restricting to 1000 kcal/d had no effect on breast milk composition or volume.13 Another study with breastfeeding overweight women found energy restriction with exercise had no adverse effects on infant growth.14 More recently, Lovelady15 suggested that once lactation is established, overweight women may reduce their calorie intake by 500 cal/d and be physically active for 45 minutes on 4 d/wk to achieve a safe weight loss of about 1 pound/week. The minimum energy requirement for most women would be between 1900 and 2500 kcal/d.16
COUNSELING THE POSTPARTUM WOMAN TO REDUCE WEIGHT RETENTION
The IOM called for counseling women on diet and physical activity to eliminate postpartum weight retention.9 Women with prepregnancy BMIs>30 and gestational weight gain of >12 kg are at the highest risk for postpartum weight retention, or gain, and the chronic diseases associated with obesity. These women are also at higher risk of shortened duration and intensity of exclusive breastfeeding. Thus, obese women are a population that should receive increased intervention for breastfeeding education and support.11,17 Researchers are exploring how diet, physical activity, and both impact weight retention.18 Colleran and Lovelady16 demonstrated that overweight/obese lactating women, beginning 4 weeks postpartum, who received individual counseling by a RDN nutritionist, using MyPyramid Menu Planner for Moms, as a resource both improved the quality of their total diet and achieved greater weight loss than women receiving usual care. Bertz et al19 found that dietary treatment provided clinically relevant weight loss in well-educated, white lactating women that was sustained 9 months after treatment with no added extra benefit noted with the addition of exercise. In their study, one on one counseling was more effective than group work, primarily because of time constraints. Communication by letter, email, and cell phone texts reduced drop-outs. Self-weighing and exercise diaries improved weight management. Researchers completing a meta-analysis of 11 randomized controlled trials concluded that regular exercise with objective goals plus intensive dietary intervention was the most effective strategy for weight loss postpartum.20
The clinician should take an inventory of what weight management resources a patient is using and how these can be adapted to integrate evidence-based nutritional and activity goals. American College of Obstetricians and Gynecologists Web site (http://www.acog.org) offers clinical resources including diet and activity logs and a fact sheet on weight loss after pregnancy.
Low Maternal Nutrient Intakes With Potential to Affect Infant Health
HISTORY OF BARIATRIC SURGERY
Women with a history of a bariatric surgery are at risk for nutrient deficiencies due to low intake of calories and/or malabsorption depending on the type of procedure. Women with a Rouen-Y require lifelong supplementation with a chewable multiple vitamin mineral, 1500 mg calcium; 800 IU vitamin D; 500 µg sublingual B12, and 325 mg chewable elemental iron. Women with restrictive procedures including the gastric sleeve require lifelong supplementation based on their dietary intake. Screening and prompt treatment of deficiencies are important.21
CALCIUM AND VITAMIN D
An estimated 43% of American women enter the lactational period with low body stores of calcium and of vitamin D.8 Almost all of the calcium in pregnant women and their fetus is located in their bones and teeth. Lactation, like pregnancy, is associated with increased bone turnover to meet needs. The calcium secreted in breast milk appears to be from a net removal of calcium from trabecular bone and by a reduction in the amount of calcium excreted in the urine. Consuming additional calcium does not appear to prevent bone loss and after weaning or resumption of menstruation calcium absorption returns to normal.22 This may not be true for women who have marginal or low dietary calcium intake, and therefore ensuring a woman obtain adequate calcium before, during, and after lactation is important for her health.
There is widespread consensus about the role of vitamin D in bone health and great interest in its role in other conditions. Emerging research links newborn and infant vitamin D deficiency with various negative clinical outcomes, including rickets, failure to thrive, type 1 diabetes, allergic disease, lower respiratory tract infections, wheezing, asthma, and other immune-related diseases.23 Breastfed infants are at risk of developing deficiency if the mother’s milk contains inadequate levels of 25-hydroxyvitamin D for infant nutrition. It has been demonstrated that when sunlight exposure is limited or restricted, intensified vitamin D supplementation of lactating mothers and infants is needed to improve vitamin D status.24 In 2008, the American Academy of Pediatrics recommended 400 IU of vitamin D supplementation of all infants but there has been a low level of adherence to this recommendation as women report reluctance to add supplements to their breast milk.2,3 Additional information on vitamin D supplementation of the infant is found at the Centers for Disease Control Web site (http://www.cdc.org/breastfeeding). Relatively few foods are good sources of Vitamin D, they are fortified milks, yogurts and cereals, soy products, egg yolks, liver, cod liver oil, fatty fish (eg, salmon, catfish, trout, mackerel, canned tuna fish, canned sardines), and beef. The traditional advice to obtain 15 minutes of sunlight/week on face, hands and legs without sunscreen has been found to be inadequate to meet vitamin D needs for many. Therefore, leading breastfeeding advocates recommend that the woman be supplemented for prevention and/or treatment of vitamin D deficiency in breastfed infants and themselves.2–24 While the DRI for vitamin D intake is unchanged at 15 mcg/d (600 IU) in lactation, 2 recent randomized controlled trials have questioned this recommendation.25 To achieve circulating serum levels of >20 ng/mL in women, considered sufficient by the IOM, at least 2000 IU/d was required, and 4000 IU/d by the second trimester of pregnancy improved physiological optimization of active vitamin D without adverse effects.25 This deficiency is now thought to be due to widespread maternal deficiency, as women who are replete with vitamin D transfer adequate amounts to their breastfed infants. As only 20% of maternal vitamin D is transferred via milk, pharmacokinetics and emerging data suggest supplementation of at least 6000 IU/d may be needed for lactating women to meet sufficiency of the breastfeeding dyad.26,27 Further research is required to establish need, safety, and efficacy of supplementation, especially at these dosages during lactation.Women with limited sun exposure, blacks, Hispanics, of lower socioeconomic status, nonmilk drinkers, obese, and with history of gastric bypass are at an increased risk of maternal and infant deficiency.
The maternal diet should have the same percentage of calories from fat as a nonlactating woman, 20% to 35%. Although there are DRI recommendations for plant oil omega-3 and omega-6 fatty acids (α-linolenic and linoleic), ongoing research emphasizes the role of longer chain fatty acids [eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)], which have no DRI, in lactation. Public health groups have made recommendations because of the contribution of DHA to normal neurological development, vision, and potentially allergy risk in the fetus and newborn, as well as the role of omega-3 fatty acids in mitigating the morbidity and mortality caused by chronic diseases.23 In 2010, in a systematic review prepared for the Dietary Guidelines for Americans Advisory Committee,8 indicated moderate evidence that increased maternal dietary intake of long chain n-3 PUFA, in particular DHA, from at least 2 servings of seafood per week, during lactation is associated with increased DHA levels in breast milk and improved infant health outcomes, such as visual acuity and cognitive development. The abstractors recommended investigating the long-term effects on infants of mothers with high and low DHA intakes. In a review conducted for the American Dietetic Association’s Evidence Analysis Library,3 the abstractors concluded that dietary supplementation with fish oil, cod liver oil, or DHA-rich oil increased a breastfeeding woman’s PUFA levels in both breast milk and the infants’ plasma phospholipids in a dose-response fashion but did not find a clinical benefit for the infant’s visual acuity and cognitive development long term.
Dietary sources for DHA and EPA are fish: tuna, pollock, salmon, cod, catfish, flounder, grouper, halibut, red snapper, shark, swordfish, tilefish, and king mackerel and krill. Lactating women should consume at least 12 ounces of fish a week, while avoiding fish known to have high levels of mercury such as shark, swordfish, king mackerel, tilefish, bowfin, bass, wild catfish, South Atlantic grouper, orange roughy, and tuna (fresh or frozen). Fish low in mercury include canned tuna, cod, flounder, halibut, herring, lobster, mahi-mahi, oysters, salmon, sardines, scallops, shrimp, white fish, tilapia, and rainbow trout.3 A mobile app and wallet card available at: http://www.purdue.edu/hhs/nutr/fish4health/ help women track intake of seafood, fish oil supplements, healthy fats, and mercury and provide easy access to state fish advisories. Sources of α-linolenic acid (ALA) include: seed oils like: chia, kiwi fruit, perilla, flax, and linseed; lingonberry, camelina, purslane, black raspberry, butternuts, hempseed, walnuts, pecan nuts, and hazel nuts. There are no standard recommendations for supplementation. Some experts suggest if a breastfeeding woman does not eat fish or plant sources of ALA she should consider supplementing with fish oil. Vegetarians and vegans have lower than normal DHA status.23
VEGETARIANS’ AND VEGANS’ NUTRIENT ADEQUACY
Surveys of American eating patterns show an increasing interest in practicing vegetarianism and veganism for political, ethical, environmental, and/or health reasons. A conservative estimate is that 5% of adults never eat fish, meat, seafood, or poultry and of those about half never eat dairy or eggs. Almost 40% express interests in vegetarian or vegan food products/meals on occasion.28 The obstetrician/gynecologist should elicit information about eating approaches that impact nutritional status. For the breastfeeding woman, the nutrients of concern include adequate B vitamins, especially B12, vitamin D, calcium, iron, and protein, including essential amino acids.6 The vitamin B12 requirement is increased by 17% during lactation.9 The IOM recommends women who limit or abstain from animal products or who have poor absorption may place their infant at risk for deficiency. It is recommended that they take a vitamin B12 supplement containing at least 2.8 mcg/d. A credible vegan Web site (VeganHealth.org) recommends lactating women supplement with 100 mcg daily or 1000 mcg twice a week. Absorption, however, is inversely related to dose, with 100% retention at 3 mcg dropping to 15% retention at 1000 mcg. The IOM recommends breastfed infants of B12-deficient mothers receive supplementation of 0.4 mcg/d from birth to 6 months and 0.5 mcg/d from 7 to 12 months. Daily calcium intake for vegans range from 500 to 600 mg and for vegetarians from 800 to 900 mg for vegetarians, falling short of needs. Increased daily protein needs can be met by including diverse vegetable protein sources throughout the day, such as soy, legumes, grains, nuts, and seeds rich in essential amino acids such as methionine and lysine.2
VITAMIN A AND IODINE
Although typically not a concern for US lactating women because intakes are adequate, the increased need for vitamin A and iodine are worth noting. The DRI for vitamin A is increased by 86%9 to both meet the woman’s needs and replace the vitamin A secreted in milk. Dietary iodine is required for thyroid hormone production. The DRI for iodine is increased in lactation to 290 mg/d9 and there may be a subset of women who avoid iodized salt and processed foods that could have low intakes. Guidelines call for women to receive 150 μg iodine supplements daily, usually through a multiple vitamin supplement.23,29
Other Substances Consumed
NUTRITIVE AND NON-NUTRITIVE SWEETENERS (NNS)
Sugar and a wide variety of nutritive sweeteners like agave nectar, honey, and cane sugar contribute sweetness and about 16 cal (from carbohydrate) per teaspoon to the diet. Women attempting to control caloric intake often see NNS. Although some consumer groups urge avoidance or caution in their use, NNS approved by the Food and Drug Administration sweeten with minimal or no carbohydrate or energy and are generally recognized as safe for lactation. NNS approved include acesulfame K, aspartame, luo han guo fruit extract (monk fruit), neotame, advantane, saccharin, stevia, and sucralose.30
Caffeine and Alcohol
Caffeine passes into breast milk, and, therefore, consumption during lactation should be limited to <200 mg/d. Unfortunately labeling of the caffeine content of foods, beverages, and supplements is not required.
The Dietary Guidelines for Americans8 suggests that 1 serving of alcohol (4 ounces of wine, 12 ounces of beer, 1½ ounce of spirits) can be part of a health promoting diet. However,consuming alcohol during lactation is controversial. Contrary to folk advice to drink beer to stimulate breast milk production, alcohol does not increase milk volume. In fact, moderate, consistent evidence shows that when a lactating mother consumes alcohol it enters the breast milk and the quantity of milk produced is reduced, leading to reduced milk consumption by the infant. Chronic consumption can inhibit milk production. In addition, alcohol is a source of non-nutritive calories. The American Academy of Pediatrics does suggest that an occasional celebratory single, small alcoholic drink is acceptable, but breastfeeding should be avoided for 2 hours after the drink as alcohol is concentrated in breast milk.3,4 In 2010, USDA reported limited evidence suggests that alcohol consumption during lactation was associated with altered postnatal growth, sleep patterns, and/or psychomotor patterns of the offspring.8
Herbal and Other Dietary Supplements
Experts agree there are few data to develop accurate information about the prevalence, efficacy, and safety of commonly used herbs during breastfeeding.31 Even so, in Lawrence and Huttel’s32 2015 chapter, some preparations such as St John’s wort for mild depression are considered tolerable, and galactogogues to improve milk supply including fenugreek, goat’s rue, alfalfa, and milk thistle are considered safe in modest doses. These authors recommend a public source of herbs to avoid during lactation, available at: http://www.earthmamaangelbaby.com
Calorie and select nutrient needs are increased during lactation, but volume and composition of breast milk is unaffected by the diet of a well-nourished woman, with notable exceptions being vitamin D and DHA. Some women will safely lose weight with a small caloric restriction, increased exercise, or a combination of the 2. Lactation provides a unique opportunity for lifestyle treatment including diet counseling for the prevention of obesity and related chronic disease.
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