Monday, September 01, 2008
Diet & Nutrition
By Diana Gnat, DC, July 31, 2008, abstracted from “Plasma Vitamin C Level, Fruit and Vegetable Consumption, and the Risk of
New-Onset Type 2 Diabetes Mellitus: The European Prospective Investigation of Cancer-Norfolk Prospective Study” in the July 28, 2008 issue of the Archives of Internal Medicine
In the past, the World Health Organization recommended that people eat a minimum of five servings of fruits and vegetables a
day in order to prevent chronic diseases.(1) One of the chronic diseases on the rise is diabetes. This disease is projected to
rise from 171 million people in 2000 to 366 million in 2030.(2) Previous research uncovered lower blood levels of vitamin C
diabetic individuals compared with healthy individuals.(3) A new study reports increased blood levels of vitamin C may reduce the risk of developing diabetes up to 62 percent.(4)
The researchers studied women and men between the ages of 40-75 for 12 years. They administered a semi-quantitative food
frequency questionnaire, a detailed health and lifestyle questionnaire, two health checkups, a starting and ending level of
vitamin C measured in the blood (most participants), a baseline HbA1C level (half participants), and follow-up monitoring of
record linkage to external sources.(4)
The researchers found a strong inverse association between blood levels of vitamin C and the risk of diabetes. A total of
21,831 men and women were studied and 423 men and 312 women developed diabetes during the 12-year study. The average vitamin C blood levels for the diabetic men and women in the study were lower than in those without diabetes (0.76 [0.32] mg/dl vs. 0.95 [0.35] mg/dl). Participants with the highest blood levels of vitamin C also typically consumed alcohol, had more than 11 years of education, had non-manual occupations, were physically active, had never smoked, and took vitamin supplements.
For those study participants with the lowest blood level of vitamin C, the median daily number of servings of fruit and
vegetables consumed was three servings for men and four for women. Those with the highest blood levels of vitamin C consumed five servings (men) and six servings (women). When comparing the levels of fruits and vegetables consumed with the reported vitamin C blood levels, there appeared to be a dose-response effect for vitamin C blood levels, but not for fruit and vegetable intake.(4) Further research should be performed on other possible sources of vitamin C intake than fruits and vegetables, such as vitamin supplements and fortified foods.
Fruits and vegetables are rich sources of vitamins, minerals, and biologically active phytochemicals. Many of these, including
vitamin C, have properties that may be protective against diabetes.(4) Diabetic people were observed to have higher levels of
oxidative stress.(5) Plausible mechanisms for reduced risk of diabetes with higher blood levels of vitamin C may be attributed to the intake of vitamins, minerals, and phytochemicals that contain these antioxidant properties.(4)
Diana Gnat is a Chiropractic Physician practicing in Plainfield, IL.
Reference:
1 World Health Organization. Fruit and vegetable promotion initiative: a meeting report. http://www.who.int/hpr/gs.fruit.and.vegetables.shtml Accessed May 12, 2005
2 Wild S, Roglic G, Green A, Sicree R, King H. Global prevalence of diabetes: estimates for the year 2000 and projections for
2030. Diabetes Care. 2004;27(5):1047-1053
3 Will JC, Ford ES, Bowman BA. Serum vitamin C concentrations and diabetes: findings from the third National Health and
Nutrition Examination Survey, 1988-1994. Am J Clin Nutr. 1999;70(1):49-52
4 Harding, A.-H. et al. Plasma Vitamin C Level, Fruit and Vegetable Consumption, and the Risk of New-Onset Type 2 Diabetes
Mellitus: The European Prospective Investigation of Cancer-Norfolk Prospective Study. Arch Intern Med. 2008; 168: 1493-1499
5 Opara EC. Role of oxidative stress in the etiology of type 2 diabetes and the effect of antioxidant supplementation on
glycemic control. J Investig Med. 2004;52(1):19-23