All about fruitarianism with a long-term fruitarian, Lena

Vitamin B12 bioavailability significantly decreases with increasing intake of this vitamin per meal. Vitamin B12 is partially degraded and loses its biological activity during cooking and storage of foods.

The intrinsic factor-mediated gastrointestinal absorption system in humans has evolved to selectively absorb active vitamin B12 from naturally occurring vitamin B12 compounds, including its degradation products and inactive corrinoids.  This absorption system is estimated to be saturated at about 1.5 - 2.0 mcg of cobalamin (B12) per meal, 50% of dietary vitamin B12 is absorbed by healthy adults with normal gastro-intestinal function.

Some plant foods, dried green and purple lavers (nori) contain substantial amounts of vitamin B12, although other edible algae contained none or only traces of it. Most of the edible blue-green algae (cyanobacteria) used for human supplements predominantly contain pseudovitamin B12, which is inactive in humans.

The bioavailability of vitamin B12 in healthy humans from fish meat, sheep meat, and chicken meat averaged 42%, 56%-89%, and 61%-66%, respectively, in eggs it seems to be poorly absorbed (< 9%).

Albert Einstein

If people are good only because they fear punishment, then we are a sorry lot indeed. 

Fructose, Glucose, Sucrose - Sugars in Plant Foods

  • Fructose and glucose are simple sugars, monosaccharides, with the general formula C6H12O6
    • Fructose, or fruit sugar, occurs naturally in fruits, some root vegetables, cane sugar and honey and is the sweetest of the sugars. 
    • Glucose, dextrose or grape sugar, occurs naturally in fruits and plant juices and is the primary product of photosynthesis. Most ingested carbohydrates are converted into glucose during digestion and it is the form of sugar that is transported around the bodies of animals in the bloodstream. 
  • Sucrose is a compound sugar, disaccharide, with the general formula C12H22O11
    Sucrose is found in the stems of sugarcane and roots of sugar beet. It also occurs naturally alongside fructose and glucose in other plants, in particular fruits and some roots (carrots). A molecule of sucrose is formed by the combination of a molecule of glucose with a molecule of fructose, and it is split into these parts during digestion.

The different proportions of sugars found in plant foods determines their sweetness Apple