28/07/2026
Really interesting and easy to understand
SWEET POTATO IS GOOD FOR VITAMIN A ?!!
This is so important to understand folks:
Plant ingredients are only nutritious for humans, dogs and cats when they're not compared to meat.
Let's take vitamin A in sweet potato as our first example.
There are two types of vitamin A there out in ingredient land: RETINOL - the type used by your body and the vitamin A that's found in meat and CAROTENOIDS (largely β-carotene, pronounced beta-carotene, the vitamin A found in plants...and virtually all pet food).
They are not the same.
Retinol (from meat) is the usable form by mammals. As a result, it is absorbed directly when consumed. β-carotene is not the vitamin A used by animals. Much like a Word file trying to open on a Mac, it must be converted to retinol by the body before it is used.
Humans are very poor at the conversion, dogs certainly no better, likely worse, and cats can't do the conversion at all.
Researchers gave women labelled β-carotene and measured its conversion into retinol in the body. They found huge differences between individuals. Some were OK at it, but the majority were very bad converters. 5 of the 11 women were described as "very low responders", with negligible absorption and conversion.
Another study, this time in men, also found enormous variability, with overall average β-carotene absorption being around 2% in this cohort (compared to 70-90% of retinol fed).
Studies suggest dogs are worse at it than humans, but for now let's assume carnivorous dogs are at least as poor as omnivorous humans at the conversion.
This means a 10kg dog, requiring 937 IU of vitamin A per day, can get what they need from just 5-6g of beef liver.
To get the same hit from plants, that 10kg dog would need to eat 90–95g of sweet potato.
That's more than 1/3 of his daily rations (most are feeding by weight - 2.5% of 10kg is 250g per day. Better you do it by calories, but that's another lesson).
Starting to see the problem?
What else is sweet potato "rich" in for the dog?
Very little, in any real sense.
It's a source of manganese, we're told, but that's very debatable. A 10kg dog eating 250g a day would have to consume 500g of (carefully prepared) sweet potato flesh to get enough!
Let's do another one.
Heme iron is vastly superior to the iron found in plant matter. Yes, spinach and beef appear to have the same amount of iron in there per 100g (2.5g) but spinach is also rich in oxalates and phytates.
These are plant-defence compounds (it's not just plant fibre you should be concerned about when feeding plant matter to carnviores!).
Oxalates are pesticides. They discourage herbivores by irritating insect mouths and reducing digestibility.
How do you feel about that notion of my using the word pesticide there? Sound nutritious? Because it's absolutely accurate.
Feel free to Google how consuming lots of oxlates is working out for humans, let alone meat-eaters (spoiler: it isn't good).
Phytates reduce mineral availability to predators, binding iron, zinc, copper, magnesium, manganese and calcium from the food matrix. Eating them comes at a cost. Seeds are full of them (some birds have evolved around the issue by evolving the enzyme phytase. Mammals did not...as we haven't been eating enough of them for long enough).
As they're rooted to the ground, plants have evolved to become chemical weapon factories. That's why eating them takes so much care - cooking, soaking, fermenting, stripping - and when that care isn't taken, you get GI issues in the short term and malnutrition in the long term.
So, back to iron. Because of plant defence compounds, they estimate we can only absorb around 2–5% of the iron in spinach versus 25% of the stuff in meat, a near 10-fold difference.
That means a 10kg dog needs to eat around 100g of red beef meat versus a kilo of spinach to get their iron needs.
Zinc is another one - pumpkin seeds are a great source?!
Let's take a look at that.
The daily zinc requirement for a 10kg is about 3.6 mg.
Seeds like pumpkin are where it’s at for zinc, apparently. They contain around 7.5mg per 100g. That's a lot. But as the seeds are so rich in phytates, which block zinc absorption, the 10kg dog needs to eat around 100-200g of seeds per day to get his hit!
With this in mind, what is your seed addition (often included in high dose for vitamin E?) doing to the mineral bioavailability of your dog's bowl ??
(Soaking removes 5-30% of phytates, depending. Germination 50%. Fermenting 50-90%. Pet food extrusion? Virtually none. They're still in there in the cooked matrix).
Beef is lower in zinc, sure (around 4.5mg per 100mg, depending), but as there are no chemical defences in prey animals (they instead run, kick, bite, headbutt, dig and fly), your dog can get 40-60% of the zinc from their meat.
In this way, if you were to swop out the 200g of pumpkin seeds for you 10kg dog for red meat, he will not only get all of his zinc but also all of his iron, selenium, iron, many b vitamins and ALL their amino acids including taurine (and we haven't spoken about carnivore nutrients like collagen, creatine and carnosine).
And that's before we add in a smidge of the nutritional powerhouses like liver, kidney, spleen and bone.
I can do this all day. Calcium from bone vs kale? For a 10 kg dog, the daily calcium requirement is about 1.5 g. That's just 25g of raw edible bone. Kale is choc FULL of defences (like brocolli, it warns you by its foul taste!). A 10kg dog would need around 1kg of kale (prepared correctly). And bones are mineral sinks (not to mention all their glucosamine and chondroitin and appropriate roughage!).
The nutrient numbers you see displayed about plant matter are the TOTAL nutrients in the plant combusted in a laboratory and measured by a machine. They are NOT what is absorbed by the gut.
Did you know that only 20-25% of the iodine in seaweed is absorbed by a human? We humans can't get at most of it.
You have been 5 times too stressed about iodine!!
You can target certain plants to get a single vitamin and mineral all you like but you'll not only have to carefully prepare it to avoid some "anti-nutrients" but you'll have to feed a LOT of it. This inevitably means more carbs or more plant fibre or more plant defence compounds or a mix of all three.
And all the while, as you make way for a greater amount of the poorer food substrate in the bowl, you're decreasing the space in there for the truly nutritious food items, like meat.
The AAFCO nutrient profile does not concern itself with ingredient-led nutrition (hence online vets begging us to stop looking at the ingredient label!!). Its focus is on using the lowest-cost ingredients on the planet (refined carbs and leftovers of human veg processing like corn pulp) to maximise the profits of its members. They then pretend (zero studies show dogs are healthier fed this way, multiple studies show the opposite) that supplementing a nutrient-deficient plant nightmare with synthetics is the BEST way we can feed our meat-eating dogs and cats.
But it's not.
***
If you sit back and consider the implications of this piece - that vitamins and minerals are far, far better sourced from meat, and that AAFCO concerns itself only with poorly absorbed synthetic supplements - what does the AAFCO profile look like when you look at it through a meat lens?
Well, I'm about to show you in Feeding Dogs 2.0.
If you want early access to my new book, I'm releasing it as a paid Substack starting October 1st, at the rate of a chapter a week. It'll probably be around 35-40 chapters.
The Substack will have a monthly fee but it will be FREE to all members of WellDog if you sign up before the end of the month.
