A basic question about carnivore nutrient imbalance


When the Australian magpie, an omnivorous bird, is exclusively fed beef mince from skeletal muscle, eventually those birds suffer bone fractures due to nutritional deficiency from a nutrient imbalance.

When fast growing mammals like weaned puppies or kittens are fed all meat diets they also get pathological fractures of their growing bones.

The underlying mechanism is an imbalance in the calcium to phosphorus ratio in the diet. Muscle meat being higher in phosphorus and lower in calcium.

At risk of scaring comments away, the disease is known as nutritionally induced secondary hyperparathyroidism.

Can this high phosphorus to calcium ratio eventually be a problem for an adult human? By resulting in calcium draw down from bone storage thinning the bones as the body’s homeostasis tries to balance the higher phosphorus intake and preserve calcium for all its important physiological functions?


Reference list

What did you learn today?
(Karen) #2

Hmmm interested in the answer as well.


Great question and waaaay above my pay grade.

(Karim Wassef) #4

I’m running DEXA to measure bone density as a carnivore and I’m not seeing it.

The animal models you cite are not really reflective of adult human biology. There is also a lot of calcium in red meat, liver, fish and eggs.

The greatest determinant is proper calcium absorption is D3 and K2. The latter is only available in an absorbable form in animal fat. Without the proper combination of calcium, D and K2… the calcium can instead cause calcification of soft tissue and loss of bone density… simultaneously.

So while animal meat alone isn’t balanced, animal meat + fat in variety is.

(⚕ lowcarb.skrinak.com ⚕) #5

Yes, great question. I found this at Diet Doctor, whose recommendation on protein intake is in the 1.5 - 2 range.

Are long term high-protein diets harmful?

Hard to say. There is some suggestion that high animal protein intake may cause osteoporosis. Many of these proteins are acidic, which require neutralization in the body. This acid is buffered in the bones and then eventually the acid is excreted as phosphoric acid. Because bone consists of Calcium bound to phosphorus, there is extra calcium which gets excreted in the urine. This leads to higher urinary calcium losses and potentially osteoporosis.

Also, there is concern that long term high-protein intake may cause scarring in the kidneys, although this is not proven.

I’m a fan of Dr. Bikman’s pro-protein research:

Though he doesn’t mention the Ca:P ratio there.

The many n=1 success I hear about carnivore diets buoy my confirmation bias, but that’s not sufficiently evidential.

(Allie) #6

I’m guessing this is why so many people say that in order to do carnivore properly for health, you need to be eating truly nose to tail.

Not me saying this, I’m not carnivore, but I’ve heard it so many times from various different authorities that it does make me believe there has to be some truth in it.


Another possibility is that humans make vit D via exposure to sunlight, magpies and puppies not so much? [thus influencing how these minerals are balanced]


The mammalian example is reflective of human mammalian biochemical physiology. We share the same pathways.

A growing animal has higher demands, this includes growing humans, so it is an amplification of a potential problem.

But you are right Karim. The opening gambit is not a study or direct observation of adult humans. And it does specify a diet of skeletal muscle meat. Not the variety you describe. Or, as @Shortstuff notes, the carnivores who eat nose to tail.

So it is a question about carnivory in the style of those that just eat rib eye steaks. That is, a diet of beef muscle.

Doesn’t Shawn Baker say he mainly, or wholly, eats steak and ground beef? It’s probably a false impression. I think Mikhaila Peterson said similar about the beef muscle specific diet due to her reactivities? I’m sure I’ll have to correct those impressions.

I think of vegans doing well on their strict diet. But as body reserves of essential nutrients start to run low, after a few years of stored nutrient draw down, they experience ill health. Caveat being their may be a minority of highly knowledgeable vegans that have balanced their diet for adequate amounts of essential nutrients.

However, we have a human adult model of draw down nutrient depletion disease, thanks to many who tried the vegan WoE.


The treatment for the birds, puppies and kittens is a calcium supplement.

Vitamin K and Vitamin D are important.

The correction of the mineral imbalance in the Ca:P ratio is the primary cure.

(Karim Wassef) #10

Not so. While we share similar pathways, we are different. For example, a rat needs to be at <1% carb to get into ketosis while humans can get there under 10%…

Our needs are also different. Most mammals make their own vitamin C. We (and many apes) do not.

So while the animal models are useful, they are far from satisfactory for drawing conclusions.


Fair enough Karim. Thanks.

It’s not conclusion drawing I’m after. The question is still at the hypothesis stage. The mammalian models are close enough to generate a concerned question.

The example and question were specified (hopefully clarified) to muscle meat only carnivore eating and expanded with the observed vegan nutrient draw down and depletion problem.

(Karim Wassef) #12

Check the cheese and then meat, fish and eggs content



Thanks Karim. There is calcium in meat. Understood.

I adjusted the initial “low calcium” mistake to “lower calcium”. In context of the Ca:P ratio.

However, there is more than twice as much phosphorus in proportion.

That creates a contextual relative calcium deficiency problem in an all meat diet. Meat in this context being skeletal muscle.

(Karim Wassef) #14

In that case, we need the antagonist to calcium in perspective as well: Magnesium. Calcium absorption is about more than bones. It plays a significant biochemical regulatory role and most SAD diets are actually deficient in magnesium. This causes calcium to be overpowering and effectively in excess. Add to that the deficiency in K2, and you have soft tissue calcification in the general aging population.

Better use of less calcium is still better than poor use of more calcium. It’s nonlinear.


What if…
You let those puppies chew on bones too?

(Karim Wassef) #16

Does bone broth count? :slight_smile:


I would say yes if they dissolve enough to be useful. I make gritty stuff myself and reuse the bones.


Yes. Any form of calcium supplementation plus animal based fats for fat soluble vitamins, and romping in the sunshine. Preferably morning sunshine so their owners get the blue light wave benefit as well. But also if puppies could chew bones properly to access the minerals. They don’t get their adult teeth fully emerged until about 5 months old. Bone chewing is just exploratory until then. Some small toy breeds are incapable. Bone broth definitely could and would form part of an antidote.


That is great picture building information Karim. Magnesium and Vitamin K2 are so important to make sure calcium goes into bones and teeth. Good points.

I think I have to present my question in a different way.

@Screenack was guiding me down the path I was looking for with the quote about phosphoric acid, buffering and calcium.

The addendum question is: Do people that go onto the carnivore diet ever just eat an exclusively muscle meat only version of the diet? The Steak Only Diet?

It would be tempting.


An attempt at shepherding the investigation.