Resveratrol and vitamin C reduces oxidative stress in postmenopausal women: Study

A new study showed that a combination of resveratrol and vitamin C increased the antioxidant capacity of postmenopausal women with insulin resistance by up to 33%.

Published in the journal Nutrients, the pilot study suggested that 500 milligrams (mg) each of resveratrol and vitamin C daily ameliorates oxidative stress, a key driver for post-menopausal metabolic diseases.  

However, during the three-month intervention, the supplement didn't show significant differences in clinical and biochemical markers for insulin resistance, prompting calls for further studies. 

The researchers in Mexico noted a lack of studies that show true statistical significance with synergistic antioxidant combinations such as resveratrol and vitamin C.

“It is the first pilot study that evaluates the combination of two antioxidants and its effect on oxidative stress and insulin resistance,” they wrote. 

Antioxidants and menopause

Changes in hormones during menopause can increase the risk of metabolic diseases such as insulin resistance, highlighting an increased need for antioxidants.  

In 2020, the current researchers reported​ that postmenopausal Mexican women present higher concentrations of oxidative stress markers than women of reproductive age. They proposed that this is due to aging, obesity, lower estrogen, and diet. 

They explained that estrogen produces direct antioxidant effects by increasing the activities of antioxidant enzymes and protecting cells from free radical damage to the mitochondrial DNA.  

Falling estrogen levels in menopause change the lipid profile and increase lipoperoxidation. If the diet in menopause is depleted of antioxidant vitamins and phytonutrients, oxidative stress may increase. 

Other research indicates that declining estrogen puts postmenopausal women at risk of insulin resistance​ and cardiovascular disease​. Oxidative stress is the key mechanism involved. 

Benefits for postmenopausal women​

The study recruited 46 women aged between 50 and 60 diagnosed with early postmenopause and presenting with insulin resistance. The participants were not taking hormone replacement therapy.

Participants were blindly randomized into one of three groups:  500 mg resveratrol, 500 mg vitamin C, or 500 mg of each together. All groups received two capsules, with a placebo replacing the other supplement in the single-dose groups. 

The study noted that antioxidants can become oxidants when present in high concentrations, and therefore administering them in pairs may avoid the generation of new free radicals that act as pro-oxidants.  

The researchers evaluated blood samples, clinical status, and antioxidants before and after three months of intervention.   

The resveratrol and vitamin C group showed a significant 33% decrease in lipoperoxidation. This was compared to a 25% and 15% decrease in resveratrol and vitamin C, respectively, which didn’t reach statistical significance due to the small sample size.  

Additionally, they found a significant 39% decrease in oxidative damage to proteins with the combination supplement.  

The total antioxidant increase was 30% in the combination group, 28% in the vitamin C group, and 11% in the resveratrol group. 

There were however no significant differences between the starting and endpoint values for weight, BMI, glucose, insulin, lipid profile, and uric acid in any of the groups.

The authors note the study's limitations, including the lack of a control group that took no supplements and the limited diversity of the participants. They recommend interpreting the findings with caution and future studies with larger sample sizes. 

Source: Nutrients 2024, 16(21), 3775; https://doi.org/10.3390/nu16213775​
“The administration of resveratrol and vitamin C reduces oxidative stress in postmenopausal women—a pilot randomized clinical trial.”
Authors: A. Montoya-Estrada et al.