Small bones: fish (sardines, etc), eaten with the fish or as broth.
Big bones: beef/lamb/pork/chicken/etc, as broth.
Eggshells, as broth.
Green leafy vegetables: darker the better, cook well and eat with fat. Avoid greens high in oxalic acid though, such as spinach, beets, celery, pecans, tea, and cocoa. (Although these aren't eaten on a carnivorous diet)
Maximising calcium:
| Absorption | Excretion | ||
| Increases | Decreases | Increases | Decreases |
| Viamin D | Phytic & oxalic acids | Fibre | Potassium |
| Animal Protein | Caffeine | Boron (-44%!) | |
| Phosphatase** | High cortisol (metabolic stress) | ||
| Magnesium* | |||
| Phosphorus* | |||
| Vitamin K2 to get it into bones and not into arteries. | |||
* Although magnesium and phosphorus help calcium balance it should not be eaten/taken at the same time as calcium as they can compete for absorption.
** Phosphatase is an enzyme in raw milk, it is destroyed when milk is pasteurised (in fact they test that this enzyme is dead to confirm it’s pasteurised). This is why most studies show milk doesn’t help bone health: they used pasteurised milk! If you want to drink milk, drink it unpasteurised.
Some other nutrients that help are copper (found in liver), iodine (seaweed, seafood), vitamin A (liver, egg yolks, dairy fats), silicon (bones, dark green leafy veg, certain spring waters), strontium (dairy, shellfish), sodium (salt), CoQ10 (heart), vitamin B5 (liver, egg yolks, dairy), boron (I can't find any good animal food sources of this), zinc (red meat), and manganese (tea/spices).
Nutrients that hinder include sugar (refined and natural), lead, cadmium, fluoride and excess phosphorus (see note above).
Weston A Price on how much calcium/phosphorus we need:
- 680mg Calcium
- 1,300mg Phosphorus
Factoring in our absorption increases from lack of phytic acid this actually comes out as needing ~544mg calcium (just over half an egg shell's worth). Regarding phosphorus, at lot of that phosphorus on a WAPF diet is locked up in phytic acid so much less is needed on a phytic acid free diet.
Bones:
Bones have lots of phosphorus, as bones are made from hydroxylapatite [Ca5(PO4)3(OH)] and some calcium carbonate. Together these make up 65% of bones, water 25%, and the remaining 10% is formed by magnesium, sodium, potassium, sulphate, and other trace minerals. This means that bones are ~10% calcium and 6% phosphorus by weight (~1.7 Ca:P ratio). As a diet of pure muscle meat has little to no calcium (unless using ground meat due to trace amounts of bone in it), adding ~600mg calcium worth of broth will actually add about ~360mg of phosphorus too, and my upcoming second version of the perfect carnivore diet menu has about ~940mg of phosphorus (and ~160mg calcium), so adding broth rather than egg shells (as used in version 1) will ~1300mg phosphorus and ~760mg calcium which is in line with the WAPF recommendations.
Breast Milk:
Breast milk contains ~320mg calcium per litre, and this is about how much an infant drinks. Not very much at all considering how fast they're growing and calcifying their bones. We can probably safely assume that an adult is unlikely to need more calcium than a growing infant, even though some calcium will be needed for bone turnover, replaces trace loss in urine, etc.
It's interesting the RDA for calcium under a year old is only 200-260mg, and jumps to 700mg at one year then 1,300mg after 4 years. Although I can't find the source at the moment, I remember reading a study looking at primitive cultures, their calcium intake and their fracture rates, many got only 200-300mg of calcium and had very little fractures, no culture ate under 200mg. This all points to us not actually needing very much calcium at all really, and rather needing more of calcium's co-factors for healthy bones.
Update (19/12/13):
I found the source I was originally referring to:
The importance of vitamin K2:Bones:
Bones have lots of phosphorus, as bones are made from hydroxylapatite [Ca5(PO4)3(OH)] and some calcium carbonate. Together these make up 65% of bones, water 25%, and the remaining 10% is formed by magnesium, sodium, potassium, sulphate, and other trace minerals. This means that bones are ~10% calcium and 6% phosphorus by weight (~1.7 Ca:P ratio). As a diet of pure muscle meat has little to no calcium (unless using ground meat due to trace amounts of bone in it), adding ~600mg calcium worth of broth will actually add about ~360mg of phosphorus too, and my upcoming second version of the perfect carnivore diet menu has about ~940mg of phosphorus (and ~160mg calcium), so adding broth rather than egg shells (as used in version 1) will ~1300mg phosphorus and ~760mg calcium which is in line with the WAPF recommendations.
Breast Milk:
Breast milk contains ~320mg calcium per litre, and this is about how much an infant drinks. Not very much at all considering how fast they're growing and calcifying their bones. We can probably safely assume that an adult is unlikely to need more calcium than a growing infant, even though some calcium will be needed for bone turnover, replaces trace loss in urine, etc.
It's interesting the RDA for calcium under a year old is only 200-260mg, and jumps to 700mg at one year then 1,300mg after 4 years. Although I can't find the source at the moment, I remember reading a study looking at primitive cultures, their calcium intake and their fracture rates, many got only 200-300mg of calcium and had very little fractures, no culture ate under 200mg. This all points to us not actually needing very much calcium at all really, and rather needing more of calcium's co-factors for healthy bones.
Update (19/12/13):
I found the source I was originally referring to:
Many people know of vitamin K1, found in dark green leafy vegetables. Vitamin K2 can be made from K1 but only in small amounts (similar to our poor beta-carotene to retinol conversion). Vitamin K1 helps blood clotting (recent studies show K2 mk-4 can do this too), but vitamin K2 has many other jobs: Vitamin D helps you absorb calcium, but vitamin K2 gets it into the bones. Without vitamin K2, absorbed calcium tends to end up in your arteries causing heart disease! Never take a calcium supplement unless you take plenty of vitamin K2 with it.
Vitamin K2 found in fermented plant foods, like natto and sauerkraut, is a different form than found in animal foods (‘Mk-4’ in animal foods, ‘mk-7’ in fermented plants). When a plant rich in vitamin K1 is fermented, bacteria turn some of it into K2 mk-7. Mk-7 doesn’t get absorbed into body tissues well so can build up in the blood. This mk-7 is actually slowly broken down into the animal form mk-4, think of it like a slow release form.
The reason K2 mk-4 is found in animal foods is because that’s the form animal made from K1. Grass-fed animal fats are rich in K2 mk-4 because their food has loads of vitamin K1 and their digestive systems are great at converting K1 to K2 (unlike ours). Any food that concentrates healthy animal fats is rich in K2 mk-4. Examples include cheese (awesome calcium + K2 combo), liver (that’s where the body stores it; foie gras (fatty goose liver) has huge amounts), and egg yolks have lots for the growing chick.
Links on k2:
http://blog.trackyourplaque.com/2007/12/food-sources-of-vitamin-k2.html
http://www.springboard4health.com/notebook/v_k2.html
http://www.drpasswater.com/nutrition_library/Schurgers2.html (research with graphs)
My recommendations:
Get at least 200-300mg calcium every day, which is about a quarter of an egg shell's worth. Make sure you eat plenty of animal protein and fats, avoid anti-nutrients, eat some liver (for the copper!), egg yolks, seafood/weed, and salt (sodium and potassium) too for the co-factors (as listed above), and drink unfluoridated water preferably one high in silicon.
At a very minimal zero carb diet, I would say to make sure you're getting more calcium than steak provides (0mg), at least eat ground meat which has traces of bone in it (1lb 30% fat ground beef has ~108mg calcium) and drink some broth or make egg shell calcium (2 shells a week provides ~285mg calcium a day).
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