R.D

On average, these studies found that vegan BMDs were 10 to 20 percent lower than those of lacto-ovo vegetarians or

nonvegetarians. Six studies found little or no significant difference in the bone health of vegans compared to that of other dietary groups

Of the three studies assessing fracture risk or fracture rates, one showed increased fracture risk in vegans, 246 and the other showed increased fracture ratesThe first, a study of Taiwanese vegetarians and vegans, estimated the risk of lumbar spine fracture to be 2.5 times higher in long-term vegans (who had been vegan for at least fifteen years) than in other vegetarians

Dietary factors known to contribute

positively to bone health include appropriate intakes of calcium, iron, zinc,

copper, boron, fluoride, magnesium, manganese, and vitamins D, K, and C.

Vegan diets tend to produce a lower metabolic acid load, reducing urinary calcium excretionHowever, vegan diets often are lower in calcium, which can also have negative consequences for

bones.

have higher intakes of a long list of these, including potassium, vitamin K,

vitamin C, folate, fruits, vegetables, and possibly soy foods. On the other hand,

they tend to have lower intakes of calcium, vitamin D, and protein. These

nutrients are all critical to the maintenance of bone homeostasis. The three

nutrients of concern to vegan bone health (calcium, vitamin D, and protein) have

been the source of major controversy among vegan advocates.

One

research team reported that only 11 percent of calcium balance is determined by

calcium intake and 15 percent by calcium absorption; 74 percent is determined

by calcium excretion (51 percent urinary excretion and 23 percent fecal

noted above, there’s

good evidence that calcium intakes below 525 mg daily can jeopardize bone

health in vegans. Until more-definitive research is released, it’s wise for vegans

to meet recommended calcium intakes. (For more information on calcium, see

to 186).

Vegan diets can be carefully constructed to support calcium balance, but

many vegans tend to fall short in calcium intake.

Unfortunately, vegans consistently consume less vitamin D than

nonvegetarians.

for vitamin

D. The Recommended Dietary Allowance (RDA) was increased by 50 percent to

15 mg (600 IU) for everyone from ages 1 to 70 and 20 mg (800 IU) for people

older than 70.

In spite of this significant increase in DRI, many experts believe that a higher

intake—25 to 50 mcg (1,000 to 2,000 IU) per day—is required to minimize the

risk of vitamin D-related diseases and disorders. It seems reasonable for vegans

to aim for this target, particularly if their exposure to warm sunshine is limited.

We

know that high protein intakes induce urinary calcium losses. However, these

losses are less significant when protein is consumed as part of a whole food,

rather than as an isolated or concentrated protein supplement. Although urinary

calcium losses were long thought to be due to the metabolic acid load induced by

dietary protein, more-recent evidence suggests that other mechanisms may be

involved.