The Functions of Vitamin C in the Body
Vitamin C is a water-soluble vitamin, meaning that your body doesn’t store it. You have to get what you need from food, including citrus fruits, broccoli, tomatoes.
You need vitamin C for the GROWTH and REPAIR of tissues in all parts of your body. It helps the body make collagen, an important protein used to make SKIN, cartilage, tendons, ligaments and blood vessels. Vitamin C is needed for HEALING wounds, and for repairing and maintaining bones and teeth. It also helps the body absorb iron from nonheme (plant) sources.
Vitamin C is an important ANTIOXIDANT, along with vitamin E, beta-carotene, and many other plant-based nutrients. Antioxidants block some of the damage caused by free radicals, substances that damage DNA. The build up of free radicals over time may contribute to the ageing process and the development of health conditions such as cancer, heart disease, and arthritis. In this sense, vitamin C is an important ANTI-AGEING nutrient.
Contributors to Low Levels of Vitamin C and Signs of Deficiency
Although being seriously deficient in vitamin C is rare nowadays, evidence suggests that many people may have low levels of vitamin C. Smoking cigarettes lowers the amount of vitamin C in the body, so smokers are at a higher risk of deficiency. Stress and pollution also drain vitamin C from the body, as does a constantly activated immune system (such as in allergies, leaky gut, auto-immune diseases).
Signs of vitamin deficiency include dry and splitting hair; gingivitis (inflammation of the gums) and bleeding gums; rough, dry, scaly skin; decreased wound-healing rate, easy bruising; nosebleeds; a decreased ability to ward off infections and accelerated ageing.
Over time, low blood levels of vitamin C contribute to the genesis of cardiovascular disease, type 2 diabetes and cancer.
The GSTT1 Gene Determines Your Ability to Process Vitamin C
Research has shown that the amount of ascorbic acid circulating in the blood can differ between people even when the same amount of vitamin C is consumed. Some people do not process vitamin C from the diet as efficiently as others and are at a greater risk of vitamin C deficiency. A recent study published in the American Journal of Clinical Nutrition has shown that the ability to process vitamin C depends on individual genetic variation in a gene called glutathione S-transferase T1 (GSTT1) (Cahill et al., 2009).
The GSTT1 Gene Has a Major Role in Detoxification
Glutathione S-transferases, or GSTs, are a large family of detoxifying enzymes that play a role in the glutathione-ascorbic acid antioxidant cycle in the human body. GSTs work with vitamin C to reduce oxidative stress and they can spare each other from oxidation. One class of the GST enzyme family is the theta class which consists of the GSTT1 enzyme.
People with the Del genotype are at a much greater risk of vitamin C deficiency
There is a common “deletion” variant in the gene that codes for the GSTT1 enzyme such that those who have two copies of the “deletion” variant do not produce a functional GSTT1 enzyme while those with even a single copy of the “insertion” version produce GSTT1 with normal functional activity.
The relationship between the deletion (or “Del”) variant of the GSTT1 gene and circulating levels of ascorbic acid have been shown to depend on the amount of vitamin C consumed (Cahill et al., 2009). This study examined 905 healthy young women and men and measured their dietary vitamin C intake and serum ascorbic acid levels. Subjects who did not meet the Recommended Dietary Allowance (RDA) for dietary vitamin C were significantly more likely to be vitamin C deficient (as assessed by serum ascorbic acid levels <11 μmol/L) than those who met the RDA. When the population was stratified by GSTT1 genotype, those with the Del genotype were at a much greater risk of vitamin C deficiency when not meeting the RDA.
Although individuals of East Asian ancestry are more likely to have the Del genotype compared to those of European ancestry (~ 50% vs. 20%), the effect of consuming less than the RDA for vitamin C and having the Del genotype on serum ascorbic acid was similar in both groups.
CANCER RISK & DETOXIFICATION
Regarding cancer risk, another study found that individuals with the Del genotype have reduced or no glutathione S-transferase activity and therefore may be unable to eliminate electrophilic carcinogens as efficiently. These individuals should take greater care to detoxify at frequent intervals (at least twice per year).
The Nutrigenomix test kit analyzes the Ins/Del variant to assess risk of vitamin C deficiency associated with low vitamin C intake. Subjects with the Del variant are at a much greater risk of vitamin C deficiency compared to those with the Ins variant. Your nutritionist can use this information, along with other known factors, including health conditions and lifestyle factors, to develop a plan for you to achieve and maintain optimal vitamin C status.
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