Spinach Words

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Spinach for Bone Health

When most people think of bone health, they usually think of calcium intake. Given that spinach is not a good source of dietary calcium (it is loaded with calcium, but very little of spinach's calcium is absorbed by the human body due to the antinutrient oxalate content), thinking of spinach in terms of promoting bone health may at first glance appear out of place.

The keys to the benefits of spinach for bone health comes in the form of Vitamin K, Vitamin A and magnesium. Spinach, along with other green vegetables brussel sprouts and broccoli, is one of the best food sources of Vitamin K (Cauliflower is by far the best source).

Calcium from other food sources gets a boost from the Vitamin K found in spinach. (Hint: Eat spinach and a calcium-rich food together.) Vitamin K is necessary in order to regulate calcium within the body - particularly acting as a "glue" to fasten calcium into bone matrix.

A 1995 research study, also citing numerous previous studies, proved that Vitamin K deficiency is associated with an increased risk of osteoporotic bone fractures. It remained debateable and a matter for further research whether Vitamin K supplementation can actually halt or reverse bone loss. What is certain, though, is that spinach, due to its high Vitamin K content, acts as an osteoporosis preventative, though may or may not be effective as a treatment. ^{(Role of vitamin K in bone metabolism. Annu-Rev-Nutr. 1995; 151-22.)}

Without Vitamin K, and for similar but different reasons also Vitamins A & D (Vit. D is best sourced from direct sunlight upon your skin, calcium is of very little benefit to human bones at all.

That said, spinach also provides significant levels of Vitamin A - albeit indirectly. Spinach contains significant levels of beta-carotene. The human body converts this beta-carotene from spinach into Vitamin A. Vitamin A is essential for cell production throughout the human body, including the formation of bone cells.

(Interestingly, research has shown that the synthetic form of Vitamin A found in supplements significantly raises the risk of bone fractures in elderly women. No such increased risk was found with natural food source Vitamin A or beta-carotene - again emphasizing the superiority of whole food nutrition over supplements. ^{Source: JAMA January 2, 2002;287:47-54, 102-103})

Additionally, there is far more to bone than just calcium. Spinach provides a number of minerals that are essential for strong and healthy bones. These include magnesium, copper, manganese, phosphorus and, particulary importantly, zinc. Zinc works synergistically with calcium to "mineralize" calcium into bone.

A Japanese animal study in 1995 showed that actual bone strength (as distinct from formation, size and so forth, for which calcium is essential) was not correlated to the calcium level, but to the magnesium level of the bone. That study concluded that spinach was one of the most promising dietary sources of magnesium. ^{(J Nutr Sci Vitaminol (Tokyo). 1995 Dec;41(6):671-85)}