Does turning milk into yoghurt increase nutritional content

I’ve been making yoghurt for a while. It’s pretty tasty. I wonder, is the yoghurt more nutritious than the milk it was made from?

Not unless the extra nutrition comes from the bacteria that have been introduced. Are you adding anything else to mixture when you make it?

Well, the bugs eat sugar and crap lactic acid, so I’d say the nutrient density of yoghurt was higher. At least it would be if you don’t whore it up with a bunch of added high fructose corn syrup or other sugars.

I think yogurt would be somewhat more macronutrient dense than the milk from which it was produced. I believe all yogurt production involves heating of the milk to a point that at least some bit of the water content of the milk boils off, thus making it more macronutrient dense. Now, if you start with 2 gallons of milk the total macronutrient value of the resulting yogurt (however much it is–presumably less than 2 gallons) probably couldn’t be higher than the total amount in the original 2 gallons. But it could be higher per unit of volume, there just would be less of it in total.

But, that being said, I don’t know much about dairy product production. It’s possible the introduction of the yogurt bacteria and the resulting biological processes involved in their consuming the milk product and generating waste maybe converts something that is in a form where humans cannot get the most macronutrients out of it and into a form where we can…in which case I suppose it is possible for the total output of yogurt to have more accessible macronutrient content than the total milk amount. But that’s a WAG.

I would also suspect strained yogurt varieties would definitely concentrate the macronutrient content (thus why Greek Yogurt is higher in macronutrient value per volume than standard yogurt.)

You’re implying that biology is a zero-sum game, but it’s not. For example, early civilizations got more nutritional value from early grains by fermenting them into beer-like stuff, increasing the population density that a given area could support. (And also helping to make the population dependent on the elite class in early redistributive economies.)

Sorry, can’t find a cite, but I believe this is covered in Jared Diamond’s “Guns Germs and Steel”. Also, I can’t remember the term for the precursors to beer.

What can happen is that the organism that ferments the source can turn relatively undigestible polysaccharides like cellulose into more digestible ones.

However, milk is designed by evolution to be an ideal source of nutrition for mammal babies, so I doubt that any fermentation process would improve its nutritional value. That’s just a guess, though.

If you’re lactose intolerant, yogurt contains the enzymes you lack to digest lactose, and so you would be able to get the nutrition from the lactose you normally can’t digest.

Yogurt, in human history, is more about preserving milk that would otherwise spoil and so in that sense, it is much more nutritious than nothing. :slight_smile:

Understanding the macronutrients from which humans can get energy (carbohydrates, proteins, and fats) and understanding the relative densities involved what you’re saying doesn’t make sense here. Sugar and HFCS are very high energy per volume foods. A single cup of HFCS has 235 carbohydrates in it, a single cup of yogurt has at most around 9g of carbohydrates and 23g of protein (cup of plain Greek yogurt.) So that’s far less macronutrient content than a cup of HFCS.

Of course lard has them both beat–at ~200g of fat per cup, and since fat is 2.25x as energy dense as carbs or protein that’s far more macronutrient content than even a cup of HFCS.

When I learned to make yogurt, the reason for bringing it to a boil was to kill anything other than the culture that was about to be introduced, and not to reduce the water content. That said, I wouldn’t be surprised if the water content does go down naturally during fermentation/culturation, and it’s quite possible that the nutritional density is higher.

However, what I recall is that the volume of yogurt out was pretty damn close to the volume of milk I started with.

It’s been 35 years, so I may be misremembering, and no doubt there are other techniques than the one I learned from “The Campus Survival Cookbook”.

Good points!

Oops! I ignored the role of milk sugar (lactose). Our ability to metabolize lactose drops by over 90% around traditional weening age. Any culture that converts lactose into something we can metabolize would increase the nutritional value.

My guess is that could happen in two ways:

  1. using the energy to create more complex proteins. This wouldn’t increase nutritional value much, because we break most proteins down into amino acids during digestion anyway, and as I mentioned above, the proteins in milk are probably pretty well fine tuned (at least, for a mammal baby).

  2. converting the lactose into another saccharide that we can metabolize.

So, yogurt might have more calories from carbohydrates, but wouldn’t have more protein value. That’s my guess, anyway.

Yeah, if the yields are close to 1:1 I doubt there is much of a concentration effect due to removed water from regular yogurt–I would assume strained yogurt would be a different story though. Although if someone makes a fat free variety that’s always going to be less macronutrient dense than the starting milk due to the removal of the milk fat.

I was curious about the possible conversion factor as I was aware of other products (like the fermented grains you mention) where certain biological/chemical processes must be used to render it to something we can get more nutritional value from, but the point about milk being optimized for mammal babies is a good one and suggests it’s probably already a pretty good macronutrient delivery system.

According to wikipedia, this turns out to be incorrect (it’s generally true only of certain Asian and African populations). My bad.

My recollection is that I learned this in an intro Bioengineering class at UMich back in 1975. I recall the professor saying that this meant that our intestines tended to have available lactose, which is why most gut bacteria are lactogens (and with some additional logic that I don’t recall, that most pathogens are lactogens).

Either my recollection is wrong or we’ve learned better. I didn’t pursue bioengineering, though it was an interesting subject.

BTW, I was using whole milk. I don’t know whether that matters.

Oh sure, but I don’t consider sugar to be a nutrient. Of protein, carbohydrates, and fats, only one of them is completely unecessary in your diet. Removing sugar and increasing the relative caloric contributions of protein and fat increases nutrient density.

Well that’s hard to argue, a nutrient is simply defined as something which provides nourishment. Since a pure cup of sugar provides a tremendous amount of energy to fuel biological processes it meets that definition whether you consider it to or not.

Specifically sugar or sucrose (or fructose for HFCS) is a macronutrient, a type of carbohydrate. Since macronutrients are defined as the broad classifications (four in total) of nutrients from which humans acquire virtually all of their energy it doesn’t make sense to exclude sugars as a macronutrient either.

Well, there’s glory for you. By the rest of the world’s definition, though, sugar is most certainly a nutrient: it provides nutrition, energy the body needs to function. What is more, your body, your brain in particular, needs it to function. It may be that your brain could get by on sugar synthesized out of protein and fat precursors, but I very much doubt whether that would be as healthy as a diet containing sufficient carbohydrate. The fact that most people in our culture get too much of it, and would be healthier getting less, does not make carbohydrate not a nutrient.

Well, if those are the rules at 500 Calories per cup vodka CAN be part of a nutritious breakfast.

It seems to me that this is similar to the conservation of energy- you can’t get more out of a system than what you put in, unless there’s some mechanism of unlocking nutrients that were unusable previously (like nixtamalization, where corn is actually more nutritious afterward), or if the bacteria that were introduced were themselves particularly nutritious. If anything, the conversion of sugars to lactic acid would reduce the nutritional content relative to the original milk.

But, AFAIK, there isn’t any sort of nixtamalization process going on, and the amount of bacteria actually added is relatively tiny (yes, they reproduce, but via materials in the milk, so the reproduced ones don’t add or detract nutritionally, and yogurt made from 1 liter of milk isn’t materially different nutritionally than drinking the original liter of milk.

Most of that is alcohol–alcohol is the fourth macronutrient (carbohydrates/protein/fats.) Nutrient again referring to nourishment and the ability of the body to run off of it, yes you could in fact fuel biological processes with a cup of vodka.

Unlike the other three though there are a lot of things that go on with alcohol that are deleterious in a fairly immediate sense when it’s consumed in large quantities (which it would need to be in order to fuel most of your daily activities.)

What it should contain is, directly, no lactose, as it has become lactic acid. Those “lactose free yoghurt” are, like the ones with “active bifidus”, merely advertising something which is part of the definition of the product (at least in the EU).

How are you defining something as “more nutritious.” Since it doesn’t really mean anything, it’s hard to reply.