VITAMIN C: HOW MUCH IS ENOUGH?

This is a cross post from the Banter
Enjoy


VITAMIN C: HOW MUCH IS ENOUGH?
By Patrick Holford
Most Animals Produce The Equivalent Of 3 to 15 Grams of Vitamin C Every Day
Vitamin C isn't a vitamin at all. It isn't a necessary component of diet, at least for all mammals with the exception of guinea pigs, fruit eating bats, the red vented bulbul bird and primates - which includes us. All other species make their own.
This they do by converting glucuronic acid derived from glucose into ascorbic acid (C6H8O6). Three enzymes are required to make this conversion. One of these enzymes, or part of the enzyme system, is missing in primates. Irwin Stone proposed, in 1965, that a negative mutation may have occurred in these species so as to lose the ability to produce vitamin C. In primates this is thought to have occurred in the region of 25 million years ago.

Mutations can and frequently do occur in nature. Only those that put a species at advantage at the time tend to become dominant. Unfortunately, reversing such mutations is highly unlikely to occur. Unlike other vitamins, vitamin C is required in large amounts which could only be supplied by a tropical diet high in fruit and other vegetation. if sufficient vitamin C could be obtained from such a diet the quantity of glucose normally used to synthesize vitamin C could be channeled towards energy production. This could conceivably have been an advantage for primates or other species.

This advantage may have come at a price. Dr. Jungblut, an early pioneer of vitamin C therapy in the 1930's, discovered that only us primates and guinea pigs were susceptible to scurvy as well as anaphylactic shock, pulmonary tuberculosis, diptheritic intoxication, a poliomyelitis-like viral infection and a viral form of leukemia. None of the vitamin C synthesizing laboratory animals had susceptibility to these diseases. This is perhaps one of the first observations that led to the idea that susceptibility to viral infections could be a consequence of vitamin C deficiency. Could humanity's history of disease - endemic infections, plagues and more recently cancer and heart disease - be the result of our inability to produce vitamin C and our inability to obtain it from the food we eat?


Vitamin C produced per day by different animal species
(equivalent for 70 Kg Man)


Goat 2,280 - 13,300 mg
Rat 2,737 - 13,902 mg
Rabbit 1,547 - 15,820 mg
Cow 1,099 - 1,281 mg
Mouse 2,352 - 19,250 mg
Sheep 1,736 mg
Cat 336 - 2,800 mg

More than 50% of People Require Over 2,500 mg to Reach Maximum Absorption
Vitamin C is One of the Least Toxic Substances Known to Man The fact that almost all species continue to make vitamin C suggests that the amount of vitamin C generally available from diet is not enough for optimum nutrition except in exceptional circumstances such as a tropical environment. The chart above shows the average amount produced by each animal, adjusted to an equivalent body weight for Man. Under normal circumstances the daily amount produced, adjusted for comparison to a 70 kg man, is somewhere between 3,000 mg and 15,000 mg, with an average of 5,400 mg.
Species of monkeys, such as the squirrel monkey, require an equivalent of 2,000 mg a day to maintain health and up to 1000 mg a day to maintain blood levels found in the wild. Animals produce variable amounts depending on their circumstances. Under conditions of stress or infection synthesis can easily quadruple. Some primates appear to require up to 2,800 mg a day equivalent to survive the long-term stresses of captivity, while guinea pigs require 3,000 mg per day to recover from anesthesia.

What about us? While a mere 60 mg a day can prevent scurvy, the deficiency disease first identified by Dr. James Lind in 1753, it would be illogical to assume that this is the optimal dose. A survey of doctors in the US found that those who were healthiest consumed at least 250 mg of vitamin C per day. A recent survey has shown that a person's vitamin status is a good predictor of their mortality risk. High blood vitamin C levels indicate a low risk for cardiovascular disease and certain types of cancer and other immune based diseases. Optimal intakes to reduce risk of such conditions would appear to be at least 500 mg per day.