Elaine Bruce, experienced naturopath, homeopath and director of the UK Centre for Living Foods, said calcium was important for building bones, but that inorganic calcium in the form of supplements would not do the job.
"You have to have organic calcium as it occurs in fresh green leafy vegetables. "What we do in our programme is maximise that intake by having it in juice form."
I am sceptical of the advantages of organic vs inorganic calcium, as defined in the paragraphs above.
"Calcium absorbability from spinach"
RP Heaney, CM Weaver and RR Recker
American Journal of Clinical Nutrition, 1988, 46,707-709.
results conclusively establish that spinach Ca is much less readily available than milk Ca.
"Gastrointestinal absorption of calcium from milk and calcium salts"
MS Sheikh, CA Santa Ana, MJ Nicar, LR Schiller, and JS Fordtran
New England Journal of Medicine, 1987, 317 (9), 532-536.
We conclude that calcium absorption from carbonate, acetate, lactate, gluconate, and citrate salts of calcium, and from whole milk, is similar in fasting healthy young subjects.
"The Bioavailability of Dietary Calcium"
Léon Guéguen & Alain Pointillart
Journal of the American College of Nutrition, 2000, 19 (90002), 119S-136S
Three sources of calcium, milk, calcium carbonate and calcium citromalate, have been extensively studied. They all ensure the efficient absorption of calcium and also ensure, over the long term, that calcium is retained and used for bone mineralization.
Of course, it is well known that Ca intake in spinach is more difficult than milk, but it sure is a green leafy vegetable. And it seems that mineral intake of calcium is just as good as milk. The
British Nutrition Foundation (as far as I am aware, considered to be a mainstream source of orthodox nutrition information) has the following to say about calcium bioavailability:
Calcium is most readily absorbed from milk and dairy products. It is often less available from plant foods where the calcium may be bound by phytates (found in wholegrain cereals and pulses) and oxalates (found in spinach and rhubarb) in foods, which makes the calcium unavailable for absorption from the intestine into the blood. However, absorption from some plant foods is good e.g. broccoli, although the amount present may be lower than in milk.
I suspect taking calcium from vegetables in liquid form would increase the concentration of the calcium, which might go some way to reducing the problem of a lower absorption, but then one has to ask the following question: what is the effect of the food matrix on bioavailability? Not sure there's an easy answer to that one.
Onto the next claim:
She said that the chlorophyll found in green plants and vegetables also contained right amount of magnesium that is essential for the uptake of calcium for healthy bones.
"The chemical composition of chlorophyll and blood is very similar which further facilitates this uptake," she added.
Well, let's be fair. Chlorophyll and heme both have a porphyrin ring. And I don't think there's much debate that eating green leafy vegetables isn't a good way to get magnesium.
But there seems to have been little work done on the absorption of cholorophyll and its metabolites during digestion. Here's a paper that tried to simulate what happens when chlorophyll is digested:
"Assessment of Degradataion and Intestinal Cell Uptake of Carotenoids and Chlorophyll Derivaties from Spinach Puree Using an In Vitro Digestion and Caco-2 Human Cell Model"
Mario G. Ferruzzi, Mark L. Failla, and Steven J. Schwartz
Journal of Agriculture and Food Science, 2001, 49, 2082-2089
Native chlorophylls were converted to Mg-free pheophytin derivatives during digestion
Oops. So, there
is some evidence that chlorophyll-like molecules can be absorbed by intestine cells (whether they enter the blood stream is a different matter) - but
they don't contain any magnesium after digestion! Pheophytins, btw, look just like chlorophyll, but crucially, with the Mg replaced by a hydrogen atom.
Back to the Nutrition Foundation:
It is present in all foods but as magnesium is found in chlorophyll, the green pigment in plants, it is abundant in dark green leafy vegetables, but much of it is bound and not readily available for absorption.
Oh dear. Not been able to back that statement up with any studies so far, though.
Perhaps some emails to the Beeb may be in order.
