All about fruitarianism with a long-term fruitarian, Lena

Thermic effect of food (TEF) is the amount of energy expenditure above the resting metabolic rate due to the cost of processing food for use and storage. The effect varies substantially for different food components. The mechanism is unknown.

A commonly used estimate of the thermic effect of food is about 10% of one's caloric intake. 

The primary determinants of daily thermic effect are: 

  1. the total caloric content of the meals,
  2. the macronutrient composition of the meals ingested.

Macronutrients:

The thermic effect of food is the energy required for digestion, absorption, and disposal of ingested nutrients, and depends on the composition of the food consumed:

  • Protein: 20-35 % of the energy consumed,
  • Carbohydrates and fats5-15 %.

Meal frequency has little to no thermic effect. 

Insulin

Thermic effect also depends on the insulin sensitivity of the individual, with more insulin-sensitive individuals having a significant effect while individuals with increasing resistance have negligible to zero effects. Both insulin resistance and obesity are independently associated with impaired thermic effect of food at rest, but "the responsiveness of thermogenesis to exercise before a meal is related to the obese state and not independently to insulin resistance per se."

Exercise

The thermic effect of food is marginally increased by 7-8 calories per hour with exercise:

  • aerobic training of sufficient duration and intensity
  • and by anaerobic weight training.

"Negative"  Caloric Balance

Celery, grapefruit, lemon, lime, apple, lettuce, broccoli, and cabbage are often claimed to have negative caloric balance, requiring more energy to digest than recovered from the food. There is no scientific evidence to show that any of these foods have a negative caloric impact.

Leonardo da Vinci

I have from an early age abjured the use of meat, and the time will come when men such as I will look upon the murder of animals as they now look upon the murder of men.

Vitamin C

Vitamin C, or L-ascorbic acid, or ascorbate, is an essential nutrient for humans, a water-soluble vitamin. Humans, unlike most animals, are unable to synthesize vitamin C, so it is an essential dietary component. 

  • Vitamin C is required for the biosynthesis of collagen (an essential component of connective tissue), L-carnitine, and certain neurotransmitters, it is also involved in protein metabolism.
  • Vitamin C is also an important physiological antioxidant and has been shown to regenerate other antioxidants within the body, including alpha-tocopherol (vitamin E). Vitamin C regenerates vitamin E by reducing vitamin E radicals formed when vitamin E scavenges the oxygen radicals. 
  • Vitamin C plays an important role in immune function and improves the absorption of nonheme iron, the form of iron present in plant-based foods.

Approximately 70%–90% of vitamin C is absorbed at moderate intakes of 30–180 mg a day. At doses above 1 g a day, absorption falls to less than 50% and absorbed, unmetabolized ascorbic acid is excreted in the urine. 

Insufficient vitamin C intake causes scurvy, which is characterized by fatigue or lassitude, connective tissue weakness, and capillary fragility.

Cells accumulate vitamin C. The total body content of vitamin C ranges from 300 mg (at near scurvy) to about 2 g.

  • High levels of vitamin C are maintained in cells and tissues, and are highest in leukocytes (white blood cells), eyes, adrenal glands, pituitary gland, and brain.
  • Relatively low levels of vitamin C are found in extracellular fluids, such as plasma, red blood cells, and saliva.

Random Article

Fruitarians.net Apple