Paleo Diet Q & A - Calcium from where?

Q: While this style of eating and living makes sense to me, I am still left with the question of how to meet the Recommended Daily Allowance (RDA) for calcium. From all I've read on the subject, it's not possible to reach the RDA with vegetable sources (unless you include fortified soy or rice milk). Since dairy isn't part of your scheme, how does a person meet the RDA? Or do you disagree with the RDA?

A: Indeed, we relieve the RDA is higher than what you would need in a Palaeolithic type diet, because:

1. The absorption rate from brassica vegetables (e.g. Kale) is slightly higher than from milk (see attached paper) and as so (and also because they have numerous health benefits), we advise the daily intake of these foods.


2. A diet with lots of vegetables and fruit is net base yielding and in contrast a diet high in grains, cheese and salt and low in fruits and vegetables (which is a characteristic of the American way of eating) is net acid yielding and this increases calcium excretion.


3. The Paleo Diet is a High protein diet and this increases intestinal calcium absorption^{1, 2} and has an anabolic effect on bone³, particularly in the context of a net base yielding diet³.


4. By avoiding grains, you decrease anti-nutrient intake, such as phytates, which decrease magnesium⁴, calcium⁵ and zinc⁵ absorption.


5. The Paleo Diet is a Low Glycemic Load diet and as so, it does not promote Hyperinsulinemia as a high grain diet. It has been known since the year I was born (1975) that high blood insulin levels cause urinary calcium loss⁶.


6. Milk has a high Insulinotropic effect, and as so it may lead to an increase in urinary calcium excretion, for the reason outlined in point 5.

Links to Relevant Papers:

• RDA of calcium


• Dietary Acid-Base Balance


• Adverse Effects of Sodium Chloride on Bone


• Calcium absorption from kale


• Diet Evolution and Aging

References:

1. Kerstetter JE, Gaffney ED, O’ Brien O, et al. Dietary Protein increases intestinal calcium absorption and improves bone balance: An hypothesis.
   In Burckhardt P, Heaney R, Dawson-Hughes B. Proceedings of the International Symposium on Nutritional Aspects of Osteoporosis, 4-6 May 2006, Lausanne,
   Switzerland. Elsevier, 2007, pp 204-216.


2. Dawson-Hughes B. Protein intake and calcium absorption – Potential role of the calcium sensor receptor. In Burckhardt P, Heaney R, Dawson-Hughes
   B. Proceedings of the International Symposium on Nutritional Aspects of Osteoporosis, 4-6 May 2006, Lausanne, Switzerland. Elsevier, 2007, pp 217-227.


3. Sebastian A. Dietary protein content and the diet's net acid load: opposing effects on bone health. Am J Clin Nutr. 2005 Nov;82(5):921-2.


4. Bohn T, Davidsson L, Walczyk T, Hurrell RF. Phytic acid added to white-wheat bread inhibits fractional apparent magnesium absorption in humans.
   Am J Clin Nutr. 2004 Mar;79(3):418-23.


5. Cordain L. Cereal grains: humanity’s double edged sword. World Rev Nutr Diet 1999; 84:19-73.


6. DeFronzo RA, Cooke CR, Andres R, Faloona GR, Davis PJ. The effect of insulin on renal handling of sodium, potassium, calcium, and
   phosphate in man. J Clin Invest 1975;55:845–55.