Prof Jennie Brand-Miller answers your questions.
I am breastfeeding my baby. What’s the connection between my diet and my milk?
In well-nourished women, there’s no real connection between your diet and your ability to produce milk. Most mothers will draw on stores built up during pregnancy to supply the building blocks of human milk. From day to day, whatever you eat, the major macronutrients – protein, fat, carbs – in your milk will remain surprisingly constant. Its energy yield will be about 250–300 kilojoules per 100 millilitres. But some vitamins and minerals will be influenced by the quality of your diet.
Protein Compared with the milk of other mammals, human milk has a very low protein concentration, less than 1 gram per 100 millilitres. By six months, it’s even less. The proteins in human milk supply all the essential amino acids for building new tissues, hormones and enzymes in your infant. They also protect against infection, help the synthesis of milk sugar (lactose) and carry some of the minerals your baby needs.
Fat This is the most variable component of human milk. It provides not only energy but also serves to carry the fat-soluble vitamins and hormones. In well-nourished women, fat averages 4 grams per 100ml. Interestingly, the higher the mother’s body fatness, the higher the level in their milk. What’s more, the nature of the fat in your diet is reflected in your milk. For example, if you consume the long chain omega-3 fats found in many fish, then your milk will also be high in these special fats.
Carbs The main carbohydrate in milk is a sugar called lactose that is similar in structure to table sugar (sucrose) but not as sweet to taste. Interestingly, human milk has the highest concentrations of lactose of any mammal’s, with around 7 grams per 100ml at peak lactation, almost double that of cows’ milk. One of the reasons for the high concentration may be the glucose requirements of our energy hungry brain. There is another form of carbohydrate in human milk that is often overlooked, even though there may be as much as 1 gram per 100ml (more than the weight of protein). Called ‘oligosaccharides’, they are complex sugars that remain undigested in the small intestine, but discourage pathogens in the small intestine and facilitate the growth of friendly bacteria in your baby’s large bowel. The beneficial bacteria produce substances that inhibit pathogens and encourage a healthy large intestine. The oligosaccharides in human milk may be another reason that breastfed babies suffer less gastrointestinal disease.
Vitamins and minerals The concentrations of water-soluble vitamins (vitamins C, B1, B2, B6, etc.) in your milk are directly linked to your current intake of these vitamins. It’s one of the best reasons to consume a healthy diet throughout lactation. The fat-soluble vitamins (A, D, E and K) are more constant, and mainly determined by your body stores. It means that any short-term deficits won’t affect the levels in your milk. The concentrations of minerals also appear to be unaffected by your short-term intake. However, it means that if you don’t eat well, your stores are being depleted as lactation progresses. Your next baby may not be as well off if you neglect your own needs during this important stage of life.
Next month I’ll look at the nutrition recommendations during lactation.
This is an edited extract from my latest book (with Dr Kate Marsh and Prof Robert Moses), The Bump to Baby Low GI Eating Plan for Conception, Pregnancy and Beyond (Hachette Australia). You can visit us HERE.
We are delighted to let GI News readers know that a US edition is on the way. The publisher is Matthew Lore of The Experiment. Matthew has published many of our books in the past and we are very happy to be working with him on this. We will keep you posted re publication details.
New GI values from GI Labs in Toronto
Kit’s Organic Fruit & Nut Bar – New low GI snack bar.
Clif Bar & Company is a privately owned American company based in Emeryville California that produces a range of organic foods and drinks for people on the go. Their latest product, Kit’s Organic Fruit & Nut Bar, is a gluten-free, soy-free and dairy-free fruit and nut snack bar that’s USDA-certified organic. ‘When I stepped back to think about what I’d want in a new snack, I knew it had to be organic, it had to be made with simple ingredients and it had to be delicious,’ says co-CEO Kit Crawford. ‘My appreciation for organic food began at a very young age, when my parents instilled in me the values of growing your own food and caring for the land.’ Available flavours include:
- Berry Almond: GI 33, available carbohydrate 22g, fibre 5g, GL 7
- Cashew: GI 27, available carbohydrate 24g, fibre 3g, GL 6
- Chocolate Almond Coconut: GI 29, available carbohydrate 20g, fibre 5g, GL 6
- Peanut Butter: GI 26, available carbohydrate 21g, fibre 4g, GL 5
GI testing by an accredited laboratory
Dr Alexandra Jenkins
Glycemic Index Laboratories
20 Victoria Street, Suite 300
Toronto, Ontario M5C 298 Canada
Phone +1 416 861 0506
Research Manager, Sydney University Glycemic Index Research Service (SUGiRS)
Human Nutrition Unit, School of Molecular and Microbial Biosciences
NSW 2006 Australia
Phone + 61 2 9351 6018
Fax: + 61 2 9351 6022