All about fruitarianism with a long-term fruitarian, Lena

In recommending intakes for vitamin D, it must be recognized that in most locations in the world in a broad band around the equator (latitudes 42°N - 42°S), the most physiologically relevant and efficient way of acquiring vitamin D is to synthesize it endogenously in the skin from 7-dehydrocholesterol by sun (UV) light exposure.

In most situations, ~ 30 minutes of skin exposure of the arms and face to sunlight can provide all the daily vitamin D needs of the body.

Skin synthesis of vitamin D is negatively influenced by factors which may reduce the ability of the skin to provide the total needs of the individual:

  • latitude and season - both influence the amount of UV light reaching the skin;
  • ageing process - thinning of the skin reduces the efficiency of this synthetic process;
  • skin pigmentation - the presence of darker pigments in the skin interferes with the synthetic process because UV light cannot reach the appropriate layer of the skin;
  • clothing - virtually complete covering of the skin for medical, social, cultural, or religious reasons leaves insufficient skin exposed to sunlight;
  • sunscreen use - widespread and liberal use of sunscreen, though reducing skin damage by the sun deleteriously affects synthesis of vitamin D.

Because not all of these problems can be solved in all geographic locations, particularly during winter at latitudes higher than 42° where synthesis is virtually zero, it is recommended that individuals not synthesizing vitamin D should correct their vitamin D status by consuming the amounts of vitamin D. 

Recommended nutrient intakes (RNIs) for vitamin D, by group, in milligrams (1/1000 g):

Infants, children, adolescents, and adults 19–50 years, pregnant and lactating women - mg a day RNI;

Adults 51–65 years - 10 mg a day RNI

Adults 65+ years - 15 mg a day RNI

Isaac Asimov

Never let your sense of morals prevent you from doing what is right.

Protein Digestibility-Corrected Amino Acid Score

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.

Fruitarians.net Apple