Vitamin C Makes Exercise Easier
Taking vitamin C may take the edge off of exercise, according to a new pilot study. Paired with a drop in heart rate, researchers found that the perceived rate of exertion during exercise fell as vitamin C levels in the body rose.
Exhaustion following physical activity can be a hurdle for dieters trying to walk off excess weight. In the current study, obese subjects supplementing this antioxidant experienced less discomfort during physical activity after just four weeks.
Researchers from Arizona State University recruited 20 moderately obese, sedentary adults looking to lose weight. In conjunction with a low-fat, low-calorie diet, the participants took 500 mg of vitamin C or a placebo for four weeks. At baseline and at the final visit, researchers measured the subjects’ moods, perceived rate of exertion, and fat burning during a 60-minute bout of moderate-intensity exercise.
Over the course of the trial, both groups lost between 8 and 10 pounds simply by cutting calories. While fat oxidation did not change between the vitamin C and control groups, the researchers saw a drop in heart rate of nearly 8 percent (about 11 beats per minute) and a 10 percent decrease in the perceived difficulty of exercise after vitamin C supplementation. Both heart rate and exertion increased marginally in the control group.
The authors explain that “heart rate is a contributing factor to perceived effort, the significant decrease in exercising heart rate noted for the vitamin C participants may have influenced the ratings of perceived exertion.”
Diet and exercise is the best way, but certainly not the easiest way to trim down. In light of the current research, vitamin C may be an effective aid to suppress the perception of distress during exercise, particularly for individuals already struggling with their weight.
Vitamin C is more than an antioxidant. Renowned for quenching free-radicals, it plays a part everything from collagen synthesis to hormone formation and fat metabolism. Although at the helm of skin maintenance, mood, and body composition—little research has demonstrated vitamin C as an ergogenic (exercise-enhancing) aid.
Weighing in on a weighty debacle, the authors report that “these data provide preliminary evidence that vitamin C status may influence fatigue, heart rate, and the perception of exertion during moderate exercise in obese individuals.”
Exercise is work, literally. As rates of obesity soar and diets degrade, finding ways to make weight loss more accessible is becoming a public priority. The authors note that in addition to having more discomfort during exercise, obese individuals have lower rates of fat oxidation—two factors that adversely affect weight loss.
During high-intensity exercise, the perception of difficulty is trailed by an elevated heart rate and high levels of lactate in the blood, researchers explain. Lactate is an indicator that the muscle is running out of fuel and is directly linked to muscle fatigue. Vitamin C was not associated with blood lactate in the current trial. A lower heart rate, they explain, is likely responsible for the positive physical and mental changes seen with vitamin C supplementation.
Vitamin C Benefits: Doubling Up Offers Better Health with Little Risk
How much vitamin C are you getting each day? A new article in Critical Reviews in Food Science and Nutrition says that your intake should be double what is currently recommended.
Scientists are speaking up about the suboptimal recommended daily allowance (RDA) of vitamin C, saying that it should be increased to 200 milligrams per day to ensure tissue and cell saturation and promote better overall long-term health. This is more than double the current recommendation of 75 milligrams per day for women and 90 milligrams per day for men.
Researchers argue that the current RDA levels are based on the prevention of vitamin C deficiency or the disease, scurvy. However, the present recommended level may not be adequate for people to reap the powerful antioxidant benefits of vitamin C. Many well-designed studies show that optimal amounts of vitamin C can aid in cell integrity and heart health.
Professor Balz Frei, director of the Linus Pauling Institute, points out that experiments designed to test the safety and efficacy of pharmaceutical drugs are not appropriate for determining the health-promoting capacities of nutrients that are required for normal metabolism. Additionally, short-term clinical studies are not able to capture vitamin C benefits, which may take years or decades of optimal consumption.
Evidence shows that there are a large number of people who are vitamin C deficient, even at the current low RDA. Various studies have found that about a quarter to a third of people are marginally deficient, and up to 20 percent in some populations are severely deficient. Smokers and older adults, for example, are at significant risk for vitamin C deficiency.
The RDA represents a minimum level of intake to avoid deficiency diseases. There is an abundant amount of research showing that intakes as great as 1,000 milligrams contribute to plasma and tissue saturation, therefore optimizing the antioxidant properties of vitamin C.
High intakes of vitamin C have not been found to be toxic to the body; however, doses of more than 1,000 milligrams may cause stomach discomfort or diarrhea. An easy fix is to consume vitamin C as a supplement along with food.
As Frei stated in a press release, “The benefit-to-risk ratio is very high. A 200 milligram intake of vitamin C on a daily bases poses absolutely no risk, but there is strong evidence it would provide multiple, substantial benefits.”
Along with guinea pigs and apes, humans are not able to produce vitamin C. Instead, we rely on the foods we consume such as kiwi, bell peppers, and citrus fruits. It can be difficult to get 200 milligrams of vitamin C just through your diet—you would need five to nine daily servings of fruits and vegetables along with a six-ounce glass of orange juice.
Isagenix can help! Be sure you are getting the vitamin C you need by supplementing your diet with Isagenix C-Lyte which contains 520 milligrams of vitamin C per serving.
How Much Vitamin C Do You Really Need?
By Susie Rockway, Ph.D.
Vitamin C, or ascorbic acid (ascorbate), is the most frequently taken dietary supplement in North America. Yet, despite its widespread use, national surveys report that 15 percent of the population still doesn’t get enough vitamin C to meet recommended amounts for health.
Initially, the Recommended Daily Intake (RDI) for vitamin C was set at 60 milligrams, the amount required to prevent scurvy. The deficiency disease—commonly characterized by bleeding gums and loosened teeth helped identify the vitamin as having an essential role in collagen formation.
However, more recent research has now made it clear that more dietary vitamin C is needed to saturate body tissues such as the brain, heart, liver, and adrenal glands.
Consequently, in 2000, the RDI was raised to 90 and 75 milligrams daily for men and women. The new values were based on studies suggesting that plasma vitamin C should be maintained at specific levels (~80 µmol/L) for good health and antioxidant activity.
This is how the “debate on how much of vitamin C is needed” began—with scientists discussing two questions:
- How much vitamin C is really needed to make an impact on plasma levels?
- Are plasma levels really the best indication of tissue saturation levels?
Of Mice and Vitamin C
While there is still not any consensus on this matter, a new, carefully designed study just published in the February issue of American Journal of Clinical Nutrition provides some clues for answering these questions.
In the study, New Zealand researchers compared “normal” mice vitamin C tissue saturation levels with “knockout” mice that were genetically engineered to lack the enzyme needed for synthesizing vitamin C in the body.
Without dietary vitamin C, they saw that tissue concentrations of ascorbate became deficient weeks before the onset of scurvy symptoms in the mice, similar to humans. During these weeks, the scientists observed that the mice exhibited signs of impaired collagen synthesis, changes in aortic wall structure, formation of atherosclerotic plaque, and activation of inflammatory processes.
Sustaining Tissue Concentration
The scientists observed that each tissue became deficient at different rates. For example, the brain maintained its vitamin C longer than other organs; however, after just two weeks of deficiency, vitamin C in the brain became depleted. To replenish these tissues to normal levels, plasma concentration had to be maintained saturated with daily ascorbate intakes.
In addition, they found that tissue levels of ascorbate became saturated more quickly when the mice ate kiwi fruit versus sodium ascorbate in water—the flavonoids present in kiwi are thought to enhance absorption of vitamin C by maintaining it in a reduced state (versus an oxidized state).
Lastly, based on the new evidence, the researchers wrote that the current RDI should receive no less than a 60 percent boost—from 75 milligrams per day to at least 120 milligrams per day—to keep not only plasma levels saturated, but also tissue levels of the brain, and organs that are unable to be measured with current methods.
The vitamin C researchers stressed the need for people to maintain an ongoing and constant vitamin C intake to sustain tissue concentration—which means consuming the scientists’ recommended amounts regularly.
What Weight Has to Do with Vitamin C
Another less well-known role of vitamin C is its involvement as a cofactor in the biosynthesis of carnitine, a molecule required for burning fat as energy fuel (fatty acid oxidation).
Interestingly, there is a direct inverse relationship with obesity (adiposity) and plasma vitamin C concentrations—as plasma ascorbate levels are decreased, fatty tissue increases (adiposity increases).
This association has led researchers to wonder whether or not decreased vitamin C levels cause less carnitine to be synthesized and if there is a relationship between less carnitine and less burning of fat for fuel.
Preliminary findings are that subjects who are vitamin C depleted have lower levels of carnitine leading to a 25 percent decrease in fatty acid oxidation (per kilogram body weight) than individuals whose vitamin C status is adequate.
The researchers speculate that reduced fat oxidation seen with vitamin C depletion may result in weight gain by two mechanisms:
- Indirectly, decreased carnitine leads to increased fatigue during exercise and this may lead to exercise intolerance
- Directly, by lipid (fat) accumulation
The prevalence of obesity in the world currently has led researchers to suggest that more attention is needed to the problem of vitamin C deficiency affecting at least 15 percent of the population, if not more.
Dr. Rockway is Isagenix’s Director of Research and Science and has more than 25 years of experience in teaching, academic research and directing research in the dietary supplement industry. After receiving a B.S. in Biology at San Diego State University, she went to University of Arizona for her M.S. in Agricultural and Nutritional Biochemistry, and then her Ph.D. in Nutritional Sciences.
Huck CJ, Johnston CS, Beezhold BL, and Swan PD. Vitamin C status and perception of effort during exercise in obese adults adhering toa calorie-reduced diet. Nutrition 2012;1-4. doi:10/1016/j.nut.2012.021
Frei B, Birlouez-Aragon I, Lykkesfeldt J. Authors’ Perspective: What is the Optimum Intake of Vitamin C in Humans? Crit Rev Food Sci Nutr 2012;52:815-29. doi:10.1080/10408398.2011.649149
- Vissers MCM, Bozonet SM, Perason JF and Braithwaite LJ. Dietary ascorbate intake affects steady state tissue concentrations in vitamin C-deficient mice: tissue deficiency after dietary ascorbate intake affects steady state tissue concentrations in vitamin C-deficient mice: tissue deficiency after suboptimal intake and super bioavailability from a food source (kiwifruit). AJCN93(2):292-301, 2011.
- Johnston CS, Corte C and Swan PD. Marginal vitamin C status is associated with reduced fat oxidation during submaximal exercise in young adults. Nutr & Metab 3(35):1-5, 2006.