In the news: Oxidative Stress in Metabolic Syndrome: Obese May Need More Vitamin E

Obesity, Inactivity & Metabolic Syndrome

Metabolic syndrome, which is closely tied to rates of obesity and inactivity, is becoming more common among Americans. As a forerunner of type 2 diabetes and early heart disease, the “syndrome” is estimated to affect 1 out of 3 adults. Hallmarks of metabolic syndrome are a thick waistline and insulin resistance – the body’s ineffective use of insulin, so that sugar builds up in the blood instead of getting into cells.

Overeating & Insulin Resistance

How overeating promotes insulin resistance isn’t fully understood, but experiments in lab animals reveal that overeating can lead to insulin resistance very rapidly, long before the animals gain much weight.

A number of mechanisms could explain this finding: high blood levels of fatty acids, inflammation, stress in the cell’s manufacturing and packaging system (endoplasmic reticulum), or oxidative stress which occurs when too many free radicals are produced for antioxidants to quell them. All of these factors have been seen in obese people who are insulin resistant. But, according to the authors of a new study, no one really knows how the whole process gets started (1,2).

The 6,000 Calorie/Day, 7-Day Experiment

To shed more light on what initiates insulin resistance with overeating and weight gain, investigators recruited 6 healthy, middle-aged men who spent one week of inactivity in a hospital setting, eating 6,000 calories daily of typical American food – about 2 ½ times their normal intake. (It would be like all day lounging and eating Double Whopper burgers with cheese, milk shakes and larges fries for each meal).

The men were weighed and had blood samples taken daily. Fat tissue was also biopsied at the beginning and close of the 7-day food extravaganza. At the end of the week, the men had gained an average 7.7 lbs. (all fat!) and experienced an average 50% decline in their insulin-stimulated glucose uptake into tissues.

No increase in fatty acid levels and no inflammatory or endoplasmic reticulum stress were seen. But after just 2-3 days, both oxidative stress and insulin resistance were present, suggesting that the initial event caused by overeating may be oxidative stress. A close look at the biopsied fat tissue, in fact, showed that oxidative stress caused damage to a key protein that transports glucose into cells (GLUT4).

The exaggerated conditions of this study make it hard to draw absolute conclusions about oxidative stress as the initiating culprit. Yet there’s no doubt that oxidative stress is important, and that many people are inactive and consume too many calories. Bottom line? Move more, eat less, and choose more antioxidant-rich fruits and vegetables.

Obese Need More Vitamin E, Get Less

Results of a new study suggest that obese people absorb less vitamin E when they really need more to help combat the effects of metabolic syndrome (3).

Researchers theorized that vitamin E as a fat-soluble vitamin, would be more available in overweight people who eat large amounts of fatty foods. They tested the theory by giving RDA levels of vitamin E along with non-fat, reduced fat or full-fat milk to healthy people and those with metabolic syndrome.

Contrary to expectations, milk with or without fat promoted absorption of vitamin E in both groups. However those with metabolic syndrome absorbed less of the vitamin than the healthy group. While it wasn’t clear how the ‘syndrome’ blunts absorption, it could impair absorption from the small intestine or decrease its ability to find it’s way to other tissues – like fat – that need vitamin E. The team is now working to determine recommendations for the increased vitamin E needed by those with metabolic syndrome.

References

1. Bodgen G, et al. Excessive caloric intake acutely causes oxidative stress, GLUT4 carbonylation, and insulin resistance in healthy men. Sci Transl Med. 7(304):304re7, Sept, 2015.
2. Akst J. The 6,000-calorie diet. The Scientist, Nov.1, 2015.
3. Mah E, et al. α-Tocopherol bioavailability is lower in adults with metabolic syndrome regardless of dairy fat co-ingestion: a randomized, double-blind, crossover trial. Am J Clin Nutr 102:1070-80, Nov. 2015.