All about fruitarianism with a long-term fruitarian, Lena

With the exception of calcium deficiency rickets in Nigeria, no satisfactory explanation has been found for the apparently low prevalence of osteoporosis in countries on low calcium intakes. On international comparisons on a larger scale, it is very difficult to separate genetic from environmental factors. Osteoporosis was largely a disease of affluent industrialized cultures. Hip fracture prevalence (and by implication osteoporosis) is consequently related to animal protein intake, but also, paradoxically, to calcium intake because of the strong correlation between calcium and protein intakes within and between societies. This could be explained if protein actually increased calcium requirement. 

Fracture risk has recently been shown to be a function of protein intake in North American women. There is also suggestive evidence that hip fracture rates depend on protein intake, national income, and latitude. Vitamin D deficiency in hip fracture patients in the developed world was established. Such fractures can be successfully prevented with small doses of vitamin D and calcium. It is therefore possible that hip fracture rates may be related to protein intake, vitamin D status, or both.

Franz Kafka

Now I can look at you in peace; I don't eat you any more.

Vitamin A

Retinoids retinol, retinal, and retinoic acid - 3 active forms of vitamin A - "preformed" vitamin A.

Beta carotene can easily be converted to vitamin A by the human body. 

Large amounts of supplemental vitamin A (but not beta carotene) can be harmful to bones.

Vitamin A keeps tissues and skin healthy, plays an important role in bone growth. Diets rich in the carotenoids alpha carotene and lycopene seem to lower lung cancer risk. Carotenoids act as antioxidants. Foods rich in the carotenoids lutein and zeaxanthin may protect against cataracts. Essential for vision lycopene may lower prostate cancer risk.

Recommended daily amount: 700 mcg - 900 mcg or 3 mg - 6 mg beta-carotene (~ 1 cup of raw cantaloupe or sweet red peppers, or 2 mangoes, or 1/5 of one baked sweet potato). 

Because the body converts all dietary sources of vitamin A into retinol, 1 mcg of physiologically available retinol is equivalent to the following amounts from dietary sources: 1 mcg of retinol, 12 mcg of beta-carotene, and 24 mcg of alpha-carotene or beta-cryptoxanthin. From dietary supplements, the body converts 2 mcg of beta-carotene to 1 mcg of retinol. Apple