Lactose intolerance
Lactose is a milk-sugar found in milk, and (in varying levels) in milk-derived dairy products, and is added (as an additive or in the form of whey etc) to various foods stuffs (bread, cereals, processed meats, potato chips, cake mix etc [1]).
Contents
Lactic acid in humans
Lactase (lactic acid) in the small intestine breaks down lactose into glucose and galactose. If dietary lactose is not sufficiently enzymatically broken down (by lactase), bacterial decomposition may cause bloating, gasses, cramps and nausea. Naturally, as humans age, their lactase level decreases, resulting in some level of lactose maldigestion, the levels differing individually.
Decrease in lactase activity
Lactose maldigestion (caused by relative lactase deficiency) can be shown by laboratory tests. Lactose intolerance is the name of the clinical syndrome, in which lactase activity has decreased to 5 to 10% of birth levels. In northern Europe nearly 5% of the adult population is lactose intolerant, compared to more than 90% in some Asian and African countries. (75% worldwide) [2] 82% of African-American adolescent girls had lactose maldigestion, but were not considered lactose intolerant.[3]
Lactococcus in milk (products)
Lactose is broken down during ripening of cheese by lactic acid. Lactic acid (from glucose fermentation) is produced by lactic acid bacteria (Lactococcus). In raw milk produced in Normandy 38 different strains of Lactococcus were identified. 97% of these strains fermented lactose.[4]
Lactose levels in cheese
Lactose levels in cheese may differ depending on the conditions of processing and ripening (pH, glucose concentration, and Lactococcus nutrient limitation). The lactic acid (lactate) consumption rate in Camembert cheese was 2.9 times higher when temperature was 16°C rather than 8°C, during ripening.[5] Lactose levels in Gouda, Edam and Cheddar cheese may vary from insignificant to significant. Cheese produced in one area of England where the manufacturing process is standardised and guaranteed, may have guaranteed lactose levels of below 0.003%.[6]
Average lactose contents of various food stuffs (Souci, SW et al, Food Composition and Nutrition Tabels, 5th edition. Medpharm Scientific Publishers Stuttgart)
| Food | Lactose in % |
|---|---|
| dried whey (whey powder) | 68.2 |
| dried skimmed milk (milk powder) | 50.5 |
| coffee creamer | 45.0 |
| dried butter milk | 44.2 |
| dried milk, whole (milk powder) | 35.1 |
| condensed milk (skimmed) | 12.8 |
| condensed milk (min. 10% fat) | 12.5 |
| condensed milk (sweetened) | 10.2 |
| condensed milk (min. 7.5% fat) | 9.2 |
| human milk | 7.0 |
| human milk, transitional (6-10th day post partum) | 6.6 |
| mare's milk (horse milk) | 6.2 |
| donkey milk | 6.1 |
| icecream | 6.0 |
| buffalo milk | 4.9 |
| camel milk | 4.8 |
| cow's milk (skimmed milk; 0.07% fat) | 4.8 |
| whey | 4.7 |
| cow's milk (1.5 to 1.8% fat) | 4.6 |
| cow's milk (3.5% fat consumers milk) | 4.6 |
| ewe's milk (sheep milk) | 4.6 |
| cow's milk (whole, raw) | 4.5 |
| goat's milk | 4.2 |
| cream (min. 10% fat) | 4.1 |
| buttermilk | 4.0 |
| fresh cheese (50% fat in dry matter) | 3.4 |
| cream (min. 30% fat) | 3.3 |
| yoghurt, reduced fat (1.5 - 1.8% fat) | 3.3 |
| cottage cheese | 3.3 |
| yoghurt (min. 3.5% fat) | 3.2 |
| quark, fresh cheese (from skimmilk) | 3.2 |
| quark, fresh cheese (20 - 40% fat in dry matter) | 2.7 |
| fresh cheese (60 - 85% fat in dry matter) | 2.6 |
| mozzarella | 2.0 |
| ricotta | 2.0 |
| emmentaler | 1.5 |
| sherbet | 1.5 |
| butter | 0.6 |
| apenzeller | 0.6 |
| gruyere | 0.6 |
| filsitter | 0.6 |
| feta cheese (45% fat in dry matter) | 0.5 |
| cheddar cheese | 0.3 |
| ricotta cheese | 0.3 |
| camembert cheese (50 fat in dry matter) | 0.1 |
| Edam cheese | 0.1 |
| Brie cheese | 0.1 |
| parmesan cheese | 0.06 |
