Older adults may be able to combat oxidative stress in their cells that may damage tissues by loading up on vitamin C, claim American researchers.
Scientists at the University of Colorado believe that oxidative stress may have played a part in previous observations of reduced resting metabolism in older adults.
Although virtually all living organisms 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," he continued.
Destructive molecules have been to shown to 'team-up' with oxygen in the human body, resulting in oxidative stress, he said. As we grow older, the effects of oxidative stress become greater. Bell maintained that some scientists believe that by destroying tissue, increased oxidative stress may contribute to many age-related ailments of older people.
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 the resting metabolism will be increased.
"We can combat the effects of oxygen free radicals by giving older adults substances known as antioxidants," said Bell. "The body produces an abundance of antioxidants 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 measured the 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 favourable influence on body weight and body fat, she said.
Jones said it was 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 unfavourable effects of free radicals and increasing resting metabolism.