Nutrition scientists reviewed the relationship between poor gut health and depletion of the antioxidants vitamin C and vitamin E in metabolic syndrome.
Metabolic syndrome is a cluster of factors which together lead to increased risk of cardiovascular disease, type 2 diabetes and other serious medical conditions. Although the precise definition varies, the American Heart Association guidelines state that an individual with three out of five of the following conditions has metabolic syndrome: abdominal obesity (waist >102 cm in men, and >88 cm in women); raised serum triglycerides (or on medication for raised triglycerides); low HDL (“good” cholesterol); high blood pressure (or on medication for blood pressure); raised fasting blood glucose.
Around 35% of the American adult population has metabolic syndrome, with a higher prevalence in older age groups. This is a major public health concern. Much research has focused on the underlying physiological mechanisms in metabolic syndrome. Nutrition scientists at Oregon State University reviewed the current research on the relationship between poor gut health, and levels of the antioxidants vitamin C and vitamin E in metabolic syndrome. They recently reported their findings in the journal Redox Biology.
Diets high in saturated fat may allow toxins and harmful bacteria to enter the immune system
Studies suggest that a diet high in saturated fat causes imbalances in the normal “good” gut bacteria, or “microbiome”, allowing harmful bacteria to grow and damage the gut lining. This, in turn, allows toxins and bacteria to enter the circulation and the body’s immune system reacts to this by producing an inflammatory response. The oxidative stress caused by the inflammation damages cells.
Vitamin C and E are vital for the body’s immune defences
The antioxidants vitamin C and vitamin E are part of the body defences against oxidative stress and they are used up and depleted during inflammation. Vitamin C protects and regenerates vitamin E, so the levels of these two antioxidants are closely linked. In addition, the damage to the gut lining in metabolic syndrome decreases the absorption of vitamin C.
“People with metabolic syndrome can eat the same amount of vitamin C as people without metabolic syndrome but have lower plasma concentrations of vitamin C,” said Professor Maret Traber from the Oregon State University, the lead author of the review, in a recent press release. “We’re suggesting that’s because this slippage of bacterial cell walls [through the damaged gut lining] causes the whole body to mount that anti-inflammatory response.”
Low vitamin C levels in metabolic syndrome may be due to gut dysfunction caused by excess fat consumption
The reviewers concluded that low vitamin C levels in metabolic syndrome are probably driven by gut inflammation and dysfunction caused by excess fat consumption. This leads to a vicious cycle of poor absorption and increased body requirements of vitamin C. This, in turn, depletes the levels of vitamin C and also vitamin E, since these two antioxidants are closely linked. Some initial studies suggest that increasing vitamin C intake may help to break the cycle of antioxidant depletion, however further research is needed to test this idea.
“What these findings are really saying to people …is to eat your fruits and vegetables,” said Prof. Traber, “Eat five to 10 servings a day and then you’ll get the fiber and the vitamin C, and you’ll really protect your gut with all of those good things,” she added.
Written by Julie McShane, Medical Writer
- Traber MG, Buettner GR, Bruno RS. The relationship between vitamin C status, the gut-liver axis, and metabolic syndrome. Redox Biology 21 (2019) doi: 10/1016/j.redox.2018.101091
- Press release: Metabolic syndrome patients need more vitamin C to break cycle of antioxidant depletion. Oregon State University Jan 2, 2019. https://www.eurekalert.org/pub_releases/2019-01/osu-msp010219.php