All about fruitarianism with a long-term fruitarian, Lena

The protein digestibility-corrected amino acid score (PDCAAS) has been adopted by FAO/WHO as the preferred method for the measurement of the protein value in human nutrition. 

PDCAAS = Amino Acid Score x Digestibility

The method is based on comparison of the concentration of the first limiting essential amino acid in the test protein with the concentration of that amino acid in a reference (scoring) pattern. This scoring pattern is derived from the essential amino acid requirements of the preschool-age child.

Although the principle of the PDCAAS method has been widely accepted, critical questions have been raised in the scientific community:

  1. the validity of the preschool-age child amino acid requirement values (more than 4 times greater than the EAA requirement for an adult),
  2. the validity of correction for fecal instead of ileal digestibility,
  3. the truncation of PDCAAS values to 100%.

The reference scoring pattern was based on studies performed more than 25 years ago on a limited number of 2-year-old children recovering from malnutrition.

According to the current official recommendations, a 2-year old child needs ~ 3x higher essential-to-non-essential amino acid ratio, and needs essential amino acids in different proportions than adult. Methionine/cysteine is the limiting essential amino acids for adults, and for children it is lysine or tryptophan.

The use of fecal digestibility overestimates the nutritional value of a protein because amino acid nitrogen entering the colon is lost for protein synthesis in the body and is, at least in part, excreted in urine as ammonia.

Charles Darwin

There is no fundamental difference between man and animals in their ability to feel pleasure and pain, happiness, and misery. 

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.

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