Lactase | primalmeded

From Nestlè Infant Formula Guide:
“Lactose-free or soy-based formulas are important for babies with a clinically proven allergy or food intolerance…”

My previous article on breastfeeding addressed the attitudes surrounding the breast vs bottle debate. As I have mentioned before, even though there is still room for improvement, breastfeeding initiation rates are not bad in most Western countries. However, the rates drop sharply by 6 months with mothers quoting different reasons for early weaning, lactose intolerance being one of the major ones.

This post is going to be quite “sciency” so I’m going to get serious and attempt to keep sarcasm to a minimum.

Self-diagnosis of lactose intolerance in both adults and babies is very common. Before drawing any conclusions let’s look at some science involved. Lactose is a disaccharide which means it is made up of two single sugar molecules: glucose and galactose. Only these monosaccharides can be absorbed through our intestine which is why mammals possess an enzyme lactase which does the job.

Lactase is one of the brush border enzymes located on the surface of our small intestine where the digestion of lactose takes place.

Microvilli house enzymes on their surface

Several types of lactase deficiency have been described.

1. Congenital lactase deficiency - this is an extremely rare genetic condition where the body makes no lactase at all. This condition is normally diagnosed in the first week of life, often even before the baby leaves the hospital due to extreme failure to thrive. These babies require intensive follow up by paediatric gastroenterologists.

2. Late onset lactose intolerance - lactase levels gradually diminish from the age of 2-7. In Asian and African populations almost 90% of people show lactose intolerance due to very low levels of this enzyme. On the other hand Northern Europeans continue to have higher levels through adulthood with only 5% considered lactose intolerant. Other populations seem to be somewhere in between with differences between individuals depending on the genetic makeup. However, even in adults, the ability to tolerate dairy also depends on the overall health of your gut. Viruses, unhealthy gut bacteria and chronic inflammation from some foods can all cause the symptoms of lactose intolerance which can be reversed. More on that later.

3. Acquired lactose intolerance in infancy – this is what I will be talking about here. I find that the lack of understanding and the myths surrounding this condition are far and wide and should concern every parent. Two major mechanisms for acquired lactose intolerance are fast intestinal transit and mucosal inflammation.

First thing you have to know is that lactose is the sugar unique to mammalian milk. Every baby needs lactose for a very specific reason. Apart from providing about 40% of energy, lactose contains galactose, a monosaccharide essential to brain development. Galactose is incorporated into glycolipids (galactolipids) and glycoproteins in the cells throughout the body and especially in the central nervous system. We are still learning the exact mechanisms and the role of galactolipids but it is obvious that depriving a growing brain of some of its building blocks might not be a good idea. Human breast milk contains the highest concentration of lactose among all mammals. This is the main reason why evolution gave us lactase.

The problem with lactase (if you can call it a problem) is that it has a slow release time in the small intestine, regardless of total quantity of lactose in a meal. This means that anything that increases the intestinal transit time also compromises the digestion of lactose. So when it comes to the digestion of milk, the slow and steady tortoise literally wins the race. If the bolus of food moves too fast there isn’t enough lactase to break down the lactose in the meal and it swooshes past into the colon. There is no lactase in the colon but there is plenty of bacteria. Happy to receive an unexpected source of energy, bacteria use fermentation to process lactose with by-products like acids and gases. The results of this lethal cocktail are quite unpleasant, whether you are a baby or an adult: bloating, diarrhoea, acidic stool causing “nappy rash” and abdominal pain.

So what causes the fast transit of the food through the intestines? Lower fat and higher carbohydrate concentration of the meal are the common culprits. If you are an adult, it’s simple enough: skim latte will send you running to the loo faster than a full-fat one. If you are a breastfed baby though your milk supply depends on the mother. Breast milk is higher is carbohydrates at the beginning of the feed with fat content gradually increasing by the end of the feed. Taking a baby off the breast too soon will result in a lower-fat feed. Therefore breastfeeding women are recommended to empty one breast completely before offering the other.

Another reason for lower-fat breast milk is the mother’s own diet. High carbohydrate low-fat diet during lactation changes the composition of the breast milk to similarly higher-carb lower-fat. Our ancestors knew this and nursing mothers in traditional societies were encouraged to eat plenty of high quality animal fats to support the growth of the infant. However, in our times ancient wisdom gives way to the cult of thin. So first they tell you that you need to lose all that pregnancy blubber pronto. Then they inform you that the best way to lose weight and stay healthy is to reduce saturated fat in your diet. Skim milk and reduced fat yoghurt are conveniently provided. And by the way, did you know that Gwyneth Paltrow follows a macrobiotic diet (and doesn’t she look like one sexy lollipop?) so why don’t you reduce your consumption of animal products as well? What’s that? Your baby has colic? She must be lactose intolerant: here is a tin of soy formula.

Aaaargh!

Let’s move on to the second common reason of transient lactose intolerance: mucosal inflammation. The inside (mucosal) surface of the small intestine is very fragile, especially in babies, and can be easily damaged. Minor viral infections affecting the gut (viral gastroenteritis) can temporarily reduce lactase concentration and cause the typical symptoms of lactose intolerance. Luckily, intestinal mucosa heals very rapidly and the damage will be completely repaired in a few weeks. In the meantime, it is recommended that the mother keeps breastfeeding, as it will speed up the healing time and prevent “nipple confusion”.

A more serious cause of mucosal damage is chronic inflammation due to a food allergy/intolerance. In addition to the typical symptoms of lactose intolerance, the baby might also show the signs and symptoms of inappropriate immune system activation (atopy): eczema/other skin complaints and asthma (rarely diagnosed in babies under 12 months old). In the context of exclusive breastfeeding, casein (one of milk proteins) is often seen as the main offender. However, the levels of casein in human breast milk are actually quite low, compared to cow’s milk, and casein allergy is a lot more common in formula-fed babies. In addition, babies that do develop casein allergy also tend to get allergic to soy protein as well. Therefore switching to soy formula rarely solves the problem. And brings a host of its own issues: phytoestrogens and aluminum toxicity among others.

The baby may also develop an intolerance to the food consumed by the mother, typically wheat, soy, milk proteins and others. If mucosal damage due to protein intolerance is suspected, the only way to treat it is to remove the offending agent from the mother’s diet, not to remove breast milk. If the symptoms appear after the introduction of solids, then every opportunity should be taken to remove wheat and soy proteins from baby’s food. If there is a history of allergies, atopy, eczema or asthma in the family it is the strongest argument yet to breastfeed and continue to do for as long as possible. Numerous studies show that breastfeeding provides strong protection against atopy in childhood and later in adulthood.

OK, I know that was a lot to take in. For the parents out there: I hope this has made some sense and dispelled some of the myths surrounding lactose intolerance. For the adults: same principles of lactose intolerance apply. Both fast intestinal transit time and intestinal damage reduce your tolerance to dairy. Only we have less enzyme to play with.

Important points:
1. Lactose is vital for baby’s nervous system development
2. Every baby is born with enough lactase enzyme to adequately process breast milk (congenital lactase deficiency excepted)
3. Lactose intolerance is a transient phenomenon in infants and breastfeeding should not be interrupted except in the most severe cases.
4. Both intestinal transit time and mucosal damage are the main factors in individual dairy tolerance in all age groups.
5. The mother’s diet can cause LI: inadequate dietary fat (especially from animal products), consumption of wheat, soybean and occasionally milk proteins.
6. Breastfeeding provides the best protection against developing allergies in infancy and later in life.