Vitamin C May Help "Juice Up" Metabolism In Older Adults, Offsetting Weight Gain

Although virtually all living things on Earth need oxygen to exist, oxygen can combine with other molecules to form toxic oxygen “free radicals,” said CU-Boulder Research Associate Christopher Bell of the kinesiology and applied physiology department. “When oxygen mixes with the wrong crowd, it also can be our enemy.”

Destructive molecules have been to shown to “buddy-up” with oxygen in the human body, resulting in oxidative stress, he said. As we grow older, the effects of oxidative stress become greater.” Some scientists believe that by destroying tissue, increased oxidative stress may contribute to many age-related ailments of older people, said Bell.

A team of CU-Boulder researchers now believes oxidative stress may have played a part in previous observations of reduced resting metabolism in older adults.

In 1998 and 2001, a group led by Assistant Research Professor Pamela Parker Jones of the kinesiology and applied physiology department published papers showing that older adults burn fewer calories at rest than their younger counterparts. This was an important finding, said Bell, demonstrating that more calories are available to turn into fat in older adults.

In 2001, Jones’ group also published a follow-up study showing that the lower metabolic rate in older adults is due in part to a decreased ability of the nervous system to support resting metabolism. Jones’ group believes this decline in neural support of resting metabolism with age may be related to increased oxidative stress.

In a new study, Bell is trying to remove the influence of oxidative stress in older adults to find out if resting metabolism will be increased.

“We can combat the effects of oxygen free radicals by giving older adults substances known as anti-oxidants,” said Bell. “The body produces an abundance of anti-oxidants when we are young, but as we age, the production goes down. This increases the importance of healthy eating for older adults because foods such as fruit and vegetables are rich in anti-oxidants.”

In preliminary experiments, Bell has measured resting metabolism before and after an infusion of vitamin C directly into the veins of older adults between 60 and 74 years old. The results show that following vitamin C infusion, resting metabolism increases on average by almost 100 calories per day, he said.

“It is possible that the removal of oxidative stress using vitamin C could lead to a significant increase in resting metabolism in these older adults,” said Jones. “This has important implications for reducing age-associated weight gain.”

In addition, higher resting metabolic rates have been linked with a reduction in risks for cardiovascular and metabolic diseases such as diabetes due to the favorable influence on body weight and body fat, she said.

Jones said it is too soon to draw definitive conclusions from the studies. But the vitamin C studies suggest older adults may be able to avoid increased body fat and some of the associated diseases by removing the unfavorable effects of free radicals and increasing resting metabolism.

Jones and her CU-Boulder team are looking for volunteers to participate in their research, which is funded by the National Institutes of Health. People over 60 years of age who are not taking medication that might affect their metabolism or cardiovascular function and would like to participate in the study are encouraged to contact Ben Garvey at 303-492-7702 or via e-mail at cvlab@spot.colorado.edu.

Benefits of participation include a physician-supervised exercise stress test; nutritional assessment of one’s daily diet; measures of body composition, including bone density and body fat content; determination of blood cholesterol concentration; and quantification of one’s resting metabolic rate.