Dietary necessity of acidity

Samin Nosrat’s Salt Fat Acid Heat book about the four essential ingredients (aspects? heat isn’t really an ingredient) of tasty food got me wondering. I can see obvious evolutionary adaptations to make us crave salt, fat, and cooked foods (sodium is required for a ton of bioprocesses, and the other two are important for macronutrient intake). But why does acidity taste good? The only thing I can think of is vitamin C, but many (most?) acids don’t have any of that, right?

There’s evolutionary value to being able to taste things, but its not all to give us good news. Sometimes its a warning. Ripe fruits are sweet. Its a message – this is the best its going to be, Salt is also an important nutrient for animals in the wild. Umani, which wasn’t Classically included, simply because the Classical writers didn’t feel like it, is another “Eat this!” message.

Under-ripe fruit is sour. Some vegetable toxins are bitter. And although you’re not really tasting hot peppers, instead just noticing tissue damage to a particularly sensitive body part, they all say, “Don’t eat this.”

Yeah, I know, many people have culturally or situationally changed their reactions to these basic tastes. And yes, they don’t apply to every situation … I know too much sugar makes me fat, I know too much salt raises blood pressure, and that some toxins aren’t noticeable by taste. But the underlying trends are there.


Actually I think most acidic (read tart) tasting natural foods available to a hunter-gatherer population anyway are fruits (berries inclusive) and some fresh vegetables … which in the wild and more often somewhat tart than they are very sweet. Acid in foods is otherwise added by fermenting something and using it as an ingredient. So probably as important to note as sweet was as a likely healthy something to eat.

Hot peppers don’t cause tissue damage. They just fool the receptors that make you think you’re taking tissue damage.

I think you are missing that “sour” tastes good to many people. And that’s not based on “culture”. When I was a toddler, my parents gave me the lemon slices out of their drinks in restaurants because I liked to eat raw lemon. I still like sour foods. (Including raw lemon, in moderation.)

yep. and by making you think you’re on fire, they’re not saying “we’re bad for you.” They’re saying “don’t eat us because you’ll destroy our seeds.” Birds don’t suffer the burning sensation of capsaicin, so they eat a chile, fly away, and drop viable seeds on the ground elsewhere in a small pile of fertilizer.

And thus begins, the first of dozens of anecdotes on what someone likes, or why spicy wings are da bomb and not a warning at all. Which is likely the sentiment that confused the o.p. to begin with. But I have a reference for sour=acidic=unripe fruit=don’t eat. Ok, ultimately, its just some guys opinion as well. But he’s in the business of food and teaching about food.

So, you mean to say that the OP is wrong, not only is there no dietary need for acid, but “sour” means “do not eat” and Nosrat is just wrong to have a whole show about how awesome it is.

Here’s an interesting publication discussing some of your questions : Evolutionary link between diet, stomach acidity -- ScienceDaily

It seems high levels of stomach acidity in birds and animals evolved to protect against food poisoning.

The paper also notes that human stomach acidity levels match those of scavengers that are exposed to more bad microbes.

Stomach acidity has nothing to do with liking acidic flavors - we produce that acid.

No we do NOT need to eat acid, there is no dietary need … or as one nutrition fad goes … to eat alkaline. Our bodies maintain our acid base balance just fine. No big advantage to drinking apple cider vinegar or to drinking alkaline beverages.

But a selection for liking “tart” (acidic) MAY have been selected for because tart often travelled with foods that were often chock full of vitamins and other healthy phytochemicals.

Note that acid is not just a “flavor” or anything in cooking. It affects all sorts of substances. E.g., it helps unfold proteins.

You can even go all the way and “cook” using acid instead of heat. Ceviche is an extreme example.

And in the context of SFAH it’s another way of saying “pH”. (Which makes a bad title and which a lot of folk wouldn’t grok.) Getting the pH of a dish right is key to having it come our properly.

Not that the acid-“cooked” food should be considered cooked from a food safety perspective.

Not sure how germane this is, but acidity in foods is what determines if they can be canned by the Hot (boiling or nearly) Water Bath method, or if the Pressure Canning method is required.

Botulism spores can’t live in a solution that is below a certain pH, so foods like jams and pickles don’t need to be pressure canned. Foods like green beans and broths do.

Tomatoes are a bit tricky, since their pH can be a bit too high to safely can by the HWB method by themselves. All modern canning instructions require that lemon juice or citric acid be added to the jar before processing by the HWB method.

Why not? If the acid is enough to denature proteins, then it’ll also kill any microorganisms, same as heat cooking would.

if your stomach isn’t acidic enough to kill something, I doubt lime juice is. And just because some proteins denature, that doesn’t mean all of them do.

They won’t die; they just won’t grow.

What about acetic acid ? Don’t you put vinegar in your salad ?

The most fundamental reason is probably to detect vitamin C (ascorbic acid) in fruits. This would be the most common sour taste encountered by our primate ancestors. Unlike most other animals, primates have lost the ability to synthesize vitamin C, because it is always present in a normal diet. (This is why it is a vitamin for us. It isn’t for most other animals.) There is no particular advantage in consuming other acidic foods, such as vinegar. We like them because we are programmed to like sour tastes due to the association with vitamin C, but these wouldn’t be found in a typical primate diet.

Many, probably most ripe fruits, such as many citrus fruits, are sour as well as sweet. The generalization that ripe fruits are only sweet and not sour as well is not correct.

Not the best scientific evidence. In any case, he’s wrong.

In fact, most ripe fruits are sour, they are just sweet as well, so it’s not obvious if you don’t think about it.

I didn’t find a reference from a source I know, but here are some charts showing the pH of common foods, including fruit:

Apples: 3.3-4.0
Apricots: 3.3-4.8
Blackberries: 3.9-4.5
Blueberries: 3.1-3.4
Cherries: 3.2-4.5
Cranberries: 2.3-2.5
Grapefruit: 3.0-3.7
Grapes: 3.5-4.5
Lemons: 2.2-2.4
Limes: 1.8-2.0
Peaches 3.4-4.1
Pears: 3.6 - 4.0
Plums: 2.8 - 3.0
Raspberries: 3.2 - 3.6
Strawberries: 3.0 - 3.9

All delicious and carrying useful nutrients.

I would also mention that most cultivated fruits we eat have been selected for sweetness over sourness. Most wild fruits that primates consume are not nearly as sweet as those we commonly eat, and many are quite sour.