Genetic Lactose Intolerance

Definition

Inability to digest lactose due to decreased or absent lactase production after weaning, determined by genetic variants of the MCM6 gene. Affects approximately 65% of the global population after childhood.

How it works

After weaning, most humans naturally reduce lactase production, the enzyme responsible for lactose digestion. This reduction is genetically programmed in certain ethnic groups, particularly those of African, Asian, or Mediterranean origin. Variants of the MCM6 gene determine lactase persistence into adulthood. Lactose intolerance causes digestive symptoms like bloating, diarrhea, and abdominal cramps when undigested lactose reaches the colon.

Role

Determines ability to digest lactose in dairy products.

Examples

• Cow's milk
• Fresh cheese
• Ice cream
• Unfermented yogurt
• Butter

Recommendations

Choose fermented or lactose-free dairy products, or replace with plant-based beverages (soy, almond, oat). Gradually consume small amounts of lactose to encourage microbiome adaptation. Ensure sufficient calcium intake from other food sources.

Key takeaway

Genetic lactose intolerance can be well-managed by adapting diet and exploring suitable nutritional alternatives.

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