Dried milk powder, followed by condensed and evaporated milk, contains the highest concentration of lactose per serving. The processing involved in these products removes water, leaving behind a highly concentrated form of milk solids and, consequently, a higher level of milk sugar. For example, some skimmed milk powders can contain over 50 grams of lactose per 100 grams of product.
The concentration factor: Dried and condensed products
Products like condensed and evaporated milk undergo a heating process that removes a significant amount of water. This process results in a product that is much thicker and sweeter than regular milk due to its high concentration of milk sugars. Lactose, the primary sugar in milk, becomes far more concentrated in these forms. This is why they are often used in desserts and baked goods where sweetness and a rich texture are desired. For individuals with lactose intolerance, these products are often the most problematic due to their extremely high lactose load.
The role of whey protein
Another category with notably high lactose content, particularly in its concentrated form, is whey protein. Whey is the liquid byproduct of cheesemaking. While whey protein supplements are popular for muscle building, their lactose content depends on the level of processing.
- Whey Protein Concentrate (WPC): The least processed form, WPC typically contains more fat, carbohydrates, and lactose. Some concentrates contain up to 3.5 grams of lactose per serving, potentially causing issues for sensitive individuals.
- Whey Protein Isolate (WPI): This type is more extensively filtered, removing a significant amount of fat and lactose. WPI is generally considered very low in lactose, often containing less than 1 gram per serving. Many lactose-intolerant people can tolerate whey isolate without adverse effects.
- Whey Protein Hydrolysate: This form is pre-digested, with lactose levels similar to isolate, making it easily absorbed and suitable for many with mild to moderate intolerance.
Fermentation and aging: The key to lower lactose
Conversely, certain dairy products have very low lactose levels due to the fermentation and aging process. This is because bacteria introduced during fermentation or present during aging consume the lactose, converting it into lactic acid. This explains why many hard, aged cheeses are low in lactose, making them a suitable option for many people with lactose intolerance. Yogurt also benefits from this process, as the live and active cultures help break down lactose.
Lactose content comparison table
To provide clarity, here is a comparison of common dairy products and their typical lactose levels. Values are approximate and can vary by brand and processing method.
| Dairy Product | Lactose Content (g per 100g) | Lactose Classification |
|---|---|---|
| Dried Milk Powder | 52.9 | High |
| Evaporated Milk | 12.7 | High |
| Condensed Milk | 12.3 | High |
| Regular Milk (Cow's) | 4.6–4.8 | High |
| Ricotta Cheese | 3.2–5.1 | High/Moderate |
| Cottage Cheese | 3.5 | High |
| Ice Cream | 3–8 | High |
| Mascarpone | 4.5 | High |
| Processed Cheese | 6.5 | High |
| Yogurt (plain) | 2–7 | High/Moderate |
| Whey Protein Concentrate | 4–10 | High/Moderate |
| Feta Cheese | 1.4 | Low |
| Cheddar Cheese | 0.1 | Low |
| Hard Cheeses (aged) | <0.1–1 | Very Low |
Unexpected sources of hidden lactose
Beyond obvious dairy products, lactose can be present in many processed and packaged foods, an issue often referred to as 'hidden lactose'. Ingredients such as whey, milk powder, milk solids, and casein can all add lactose to a finished product. This is why checking food labels is crucial for sensitive individuals. Common culprits include:
- Baked goods (breads, crackers, pastries)
- Processed meats (sausages, hot dogs, deli meats)
- Salad dressings and sauces
- Candy, sweets, and chocolate (especially milk chocolate)
- Sweeteners (some brands use lactose as a filler)
- Medications (lactose can be used as an inactive filler)
Conclusion
While it's clear that what dairy has the highest lactose are concentrated milk products like dried milk powder and condensed milk, lactose content varies widely across the dairy spectrum. Hard, aged cheeses are often well-tolerated due to their very low lactose levels, while fresh cheeses, ice cream, and whey protein concentrate can be more problematic. For those with lactose intolerance, understanding the different types of dairy and the processing methods is key to managing symptoms effectively. Always check food labels, especially for hidden lactose in processed items, to make the best dietary choices. Seeking advice from a healthcare provider or a registered dietitian can provide personalized guidance. For more on managing intolerance, resources like the Monash FODMAP blog provide valuable information on lactose content and dietary strategies.
