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Raw milk advocates seem to claim one of two things regarding the lactase enzyme (not to be confused with the lactose sugar):

  1. That raw milk contains lactase which is destroyed in the pasteurisation process
    or
  2. That raw milk contains bacteria (or probiotics) that produce lactase and these bacteria are destroyed in the pasteurisation process.

Example (emphasis added):

Our products have what Mother Nature intended, a diversity of good bacteria and a wide range of essential enzymes including lactase for lactose digestion and phosphatase that is essential for the utilization of calcium.

One reason raw milk is so much easier to digest compared to pasteurized milk is due to the presence of lactase, the enzyme that breaks down milk sugar and which many humans are unable to produce. The experts I have spoken with deny the presence of lactase in raw milk; however, it is the friendly bacteria in raw milk that facilitate the creation of lactase in the intestine where it is needed. That is why lactose-intolerant people can drink raw milk without a problem. Pasteurization kills these friendly bacteria. source

The conclusion of these two specific "pro raw milk" arguments is the same, pasteurised milk contains no lactase, and this does seem to be backed up scientifically. However, I am skeptical that raw milk does contain lactase or that raw milk contains lactase-producing bacteria.

So, does raw cows' milk contain lactase or bacteria that could produce lactase in sufficient quantities for it to have any impact on human digestion of milk?

If it does contain lactase-producing bacteria, what is this bacteria and where does it originate from?

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  • This study is not an answer to the question, but may go a long way to explain the (likely) misconception that raw milk is better for people who are lactose-intolerant.
    – Flimzy
    Oct 22, 2013 at 1:21
  • A side-note, but if the 'feature' or raw milk is really that it allegedly has lactase in it, you can already buy ordinary pasteurized milk with lactase added (liddells.com.au/our-products/lactose-free-milk and liddells.com.au/lactose-free-dairy). This neatly confers the supposed advantage, without any of the potential disadvantages of raw milk.
    – bloopletech
    Nov 8, 2013 at 3:02
  • "what Mother Nature intended" Did Mother Nature intend humans to drink cow milk?
    – RedSonja
    Mar 10, 2015 at 12:16
  • @RedSonja "Mother Nature" didn't intend anything. Moth nature is a personification of historical processes connected with the earth with the exemption of human civilisation. The evolutionary process has no aim, and the only direction is short-term direction in increasing fitness (and even that is not completely true).
    – Colombo
    Nov 7, 2019 at 19:58
  • @Colombo Agree totally. Which is why I was being sarcastic.
    – RedSonja
    Nov 8, 2019 at 12:01

1 Answer 1

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TL;DR: No, there is no lactase in raw milk. No, there are no probiotic organisms in raw milk that produce lactase. Some (named) lactase-producing microorganisms are added to yoghurt.

The US Food and Drug Administration (FDA) have issued a statement about Raw Milk.

Raw Milk Misconceptions and the Danger of Raw Milk Consumption:

There is no indigenous lactase in milk.

Raw milk advocates claim that raw milk does not cause lactose intolerance because it contains lactase secreted by “beneficial” or probiotic bacteria present in raw milk. [...] raw milk does not contain probiotic organisms.

Fermented dairy products, especially yogurt, have been reported to ease lactose mal-absorption in lactose intolerant subjects. This enhanced digestion of lactose has been attributed to the intra-intestinal hydrolysis of lactose by lactase secreted by yogurt fermentation microorganisms. However, raw milk does not contain the same types of microorganisms at the similar levels that are found in yogurt. Yogurt that showed a benefit towards lactose intolerance typically contained 107cfu/ml or higher levels of Streptococcus thermophilus and Lactobacillus bulgaricus, and these microorganisms were purposely inoculated during yogurt manufacturing.

The FDA page contains links to journal articles to support their claims, which I have omitted in this summary.

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  • 4
    The claim "raw milk does not contain probiotic organisms" is suspect (IMHO), based on their rediculously narrow definition of "probiotic organisms" (found later in the same document): Probiotic microorganisms must be of human origin in order to have an impact on human health. This definition does not exclude the possibility of a bacteria, not classified as probiotic, which creates, or aides in the creation of the lactase enzyme.
    – Flimzy
    Oct 22, 2013 at 1:07
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    I would also encourage citing original research, especially on such a contentious issue as this one, where the FDA has what many consider to be a very anti-raw-milk bias.
    – Flimzy
    Oct 22, 2013 at 1:08
  • That is odd. Before I chase it down, I thought I would share Wikipedia's explanation: 'The World Health Organization's 2001 definition of probiotics is "live micro-organisms which, when administered in adequate amounts, confer a health benefit on the host". This definition, although widely adopted, is not acceptable to the European Food Safety Authority because it embeds a health claim which is not measurable.'
    – Oddthinking ♦
    Oct 22, 2013 at 1:13
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    These suppliers argue that "human origin" (i.e. derived from human faeces) should not be a relevant criteria. In any case, it doesn't seem to affect the FDA's basic assertion that milk doesn't contain the relevant microorganisms.
    – Oddthinking ♦
    Oct 22, 2013 at 1:25
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    @Oddthinking I agree with Flimzy that the wording of FDA the statement is ambiguous at best. The wording allows for a scenario where raw milk could contain bacteria that are non-human in origin that produce lactase. Those leaning towards conspiracy could argue it appears to be purposefully worded in such a manner. I think citation of a more clearly worded source would be in order before this could be accepted as a valid, reputable answer.
    – Scott
    Oct 28, 2013 at 5:37

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