From the Guidelines
Lactose digestion capacity generally decreases with age in humans, with a significant decline in lactase enzyme production after the age of two years in most non-Caucasian population groups 1. Specifically:
- Infants and young children: Usually have high lactase enzyme levels to digest breast milk
- Adolescents and adults: Experience reduced lactase enzyme production, leading to lactose intolerance, with lactase activity decreasing rapidly in most non-Caucasian population groups after the age of two years 1
- Older adults: Tend to have even lower lactase levels and increased lactose intolerance This age-related decline is due to a genetically programmed reduction in lactase enzyme production after weaning, known as lactase non-persistence. However, some populations, particularly those of Northern European descent, have evolved lactase persistence and maintain the ability to digest lactose throughout adulthood, as lactase activity may persist as a highly penetrant autosomal dominant characteristic in this population 1. For those experiencing lactose intolerance with age, options include:
- Consuming lactose-reduced dairy products
- Taking lactase enzyme supplements before consuming dairy
- Gradually introducing small amounts of dairy to build tolerance
- Choosing non-dairy calcium sources like leafy greens or fortified plant-based milks Understanding your individual lactose tolerance can help in managing diet and avoiding discomfort as you age, and it is essential to note that lactase deficiency may also occur as a rare primary congenital defect or secondarily as a result of small bowel disease such as coeliac disease, gastroenteritis, or non-steroidal anti-inflammatory drug use 1.
From the Research
Age-Related Capacity for Lactose Digestion
- The ability to digest lactose, a sugar found in milk and dairy products, decreases with age in most people 2, 3.
- With the exception of people of Caucasian descent, lactase activity, the enzyme responsible for breaking down lactose, decreases significantly at around 2-6 years of age 2, 3.
- By adulthood, approximately 70% of the global population has low lactase activity, making them deficient in intestinal lactase and potentially lactose intolerant 4.
- However, some individuals can still consume small amounts of lactose without experiencing symptoms, and certain dairy products like cheese and yogurt may be better tolerated due to their lower lactose content or the presence of lactase-producing bacteria 2, 3.
Lactose Intolerance and Digestion
- Lactose intolerance occurs when the body is unable to digest lactose, leading to symptoms like bloating, flatulence, and diarrhea 2, 3.
- The severity of lactose intolerance varies among individuals and populations, with some people able to consume moderate amounts of lactose without issues 5.
- The colonic microbiome plays a role in lactose digestion, and lactose feeding can support the growth of lactose-digesting bacteria in the colon, potentially reducing intolerance symptoms 4.