The Very Important But Misunderstood Role of Vitamin C In Our Health
Vitamin C is one of the well-known vitamins. It is also known as ascorbic acid or ascorbate. The reported benefits from vitamin C range from helping us get rid of colds to acting as a significant antioxidant, to helping us make connective tissues. Vitamins are nutrients vital for life that can be obtained by a “healthy” diet. Most animals can make ascorbate; humans can’t. Primates, which humans are, lost the ability to synthesize it over 60 million years ago, relegating it to the status of a vitamin. The modern history of the discovery of vitamin C is an interesting one, and, as you will see, we are still uncovering new information about its role in our health. More interesting is the evolutionary history of vitamin C metabolism in humans, which is somewhat unique among the animal kingdom, and has led to confusion over the amount we need in our diet.
Vitamin C Deficiency and Scurvy
Man With Scurvy https://commons.wikimedia.org/wiki/File:38_year_old_man_suffering_from_scurvy._Baumgartner,_1929_Wellcome_L0074309.jpg
In a 1497 expedition, Vasco da Gama lost 68% of his crew mostly to scurvy. (1) The sailors' diets consisted of biscuits and beef jerky, which is woefully inadequate at providing vitamin C and other critical nutrients. Scurvy is a terrible condition with multiple symptoms including anemia, depression, muscular pain, bone pain, shortness of breath, swelling, bleeding under the skin, unusual curling of the hair, bleeding gums, gum disease, tooth loss, poor wound healing, and death. (2) John Woodall recommended lemon juice to prevent and cure scurvy in 1617. (3) The British navy eventually provided lime juice to their sailors; hence the name “Limey” was used to describe them. Scurvy can come on quite rapidly. Two studies conducted in the mid-twentieth century, one demonstrating the symptoms could start after one month; the other showed it took six to eight months. (4,5) Both of the studies were done on patients eating high carbohydrate diets. More on this topic later.
Discovery of Vitamin C and Recommended Doses
Vitamin C was isolated in the early 20th century and synthesized in 1933. (6) The recommended allowances vary from country to country and range from 40mg/day to 110mg/day. The upper limit of vitamin C is 2,000mg/day due to diarrhea and other gastrointestinal disturbances associated with higher doses. Traditionally, RDA’s reflect the lowest amount needed to prevent deficiency; In the case of vitamin C, prevention of scurvy. On the one hand, the current RDA for vitamin C largely exceeds the amount necessary to prevent scurvy which is 10mg/day. On the other hand, researchers such as Balz Frei believe the recommendations are too low, citing in 2002 that “vitamin C supplementation lowers hypertension, endothelial dysfunction, chronic inflammation, and Helicobacter pylori infection, which are independent risk factors of cardiovascular diseases and certain cancers.” Indeed, high doses of vitamin C are frequently taken as an OTC pharmaceutical agent to treat numerous ailments such as shortening the length of colds, increasing iron absorption, treating cardiovascular disease, and cancer. Many of the claims touting large doses of ascorbate come from Linus Pauling, who was an early proponent of high dose vitamin C. (7) Countering Paulin, Dr. Bjelakovic and associates found in 2013 that antioxidant supplements like vitamin C are not associated with lower death-rates. (8) If you are confused right now, you should be.
Vitamin C and Human Evolution
A deeper dive into vitamin C metabolism and human nutrition should put things more into focus. I mentioned earlier that humans lost the ability to make ascorbic acid 60 million years ago. The predominant protein in the body is collagen, which makes up 30-40% of all proteins, and we can’t synthesize it without vitamin C. However, if we consume meat (that already contains the precursors of collagen), we don’t need to make it, relegating vitamin C to perform its other functions. (9)
Red Blood Cells to the Rescue
Humans and primates and the few other animals that don’t synthesize ascorbate, carry GLUT1 receptors on their red blood cells that grab onto and recirculate vitamin C back into action. Animals that can make vitamin C don’t have GLUT1 receptors on their red blood cells. (10)
Uric Acid and Its Role as a Potent Antioxidant
During primate evolution, the ability to metabolize uric acid mutated out. It turns out that uric acid is a very potent antioxidant and is about as effective an antioxidant as ascorbate. Plasma uric acid levels in humans are considerably higher than vitamin C levels, making it one of the major antioxidants in humans. (11) In essence, we lost one antioxidant and gained a better one.
The called Glucose-Ascorbate Antagonism Theory
Getting back to the GLUT1 receptor, it turns out that not only the receptor for vitamin C but glucose as well. Studies show that higher glucose levels competitively inhibit the uptake of vitamin C into cells. All carbohydrates end up as glucose, by the way. Our modern diets are much higher in processed carbs than our paleolithic ancestors, partially explaining our need for more vitamin C. The sugar in your orange juice could cause some of the vitamin C contained in it to be excreted instead of being fully utilized. Glucose also impairs the re-absorption of vitamin C by the kidney, and so, the higher the blood sugar, the more vitamin-C will be lost in the urine. (12,13) This phenomenon is called Glucose-Ascorbate Antagonism Theory.
The Curious Case of Vilhjalmur Stefansson and His Scurvy-Fighting Superpower
Vilhjalmur Stefansson spent eleven years in the arctic, nine of which he ate almost exclusively meat, as did the Inuits that he accompanied. He only witnessed three cases of scurvy, which happened to individuals eating canned food and very little meat. The scurvy disappeared by introducing meat back into the diet. Fresh meat does, in fact, contain vitamin C, contrary to what the USDA database says. Where there is collagen, there is bound vitamin C. Liver contains even higher amounts of ascorbic acid. (14) Stefansson and one of his crew were subjects at Bellvue Hospital, where they ate a meat-only diet. After 375 days, they were examined and suffered no ill health consequences, leaving a strong impression that a zero carb fresh meat-based diet does not lead to scurvy.
Conclusion
Vitamin C is critical for life. The discovery of vitamin C occurred after our shift to processed foods. The subjects of all of the studies to determine the RDA of vitamin C were eating carbohydrate-rich modern diets, which, as we now know, increases our need for it. The diets of the old-time sailors contained beef jerky, not fresh meat, so it did not contain ascorbate. In these settings, the need for vitamin C is much higher due to Glucose-Ascorbate Antagonism, and the lack of vitamin C in the diet. Northern paleolithic peoples would have had little to no fruits and vegetables, yet somehow they survived on diets devoid of them without scurvy. The truth is that the fresh meat and low carbohydrate environment kept them healthy.
Should We be Concerned With Vitamin C Deficiency?
Vitamin C deficiency is of little concern today. It is easy to obtain because of the global produce market and the availability of fresh meat. As long as we eat a nutrient-dense diet devoid of processed carbs, we should be ok. The Glucose-Ascorbate Antagonism mechanism is one more great reason to lay off the processed carbs.
Vitamin C and Gum Disease
Gum disease is closely linked to a poor diet, so dentists should concern themselves with their patient’s nutrition when it is present. Since the gums are one of the first areas to be affected by vitamin C deficiency, dentists should be curious about the level of processed carbohydrate consumption, as well as how much vitamin C containing produce patients are consuming. As always, a nutrient-dense diet devoid of processed carbohydrates containing both plants and meat is a safe bet.