NR Counteracts the Metabolic Aging Effects of Processed Food, New Study Suggest

Highlights:

• NR counteracts fructose-induced weight gain in mice. 
• NR promotes the fat-burning potential of fat cells by stimulating a phenomenon known as browning.

Fructose, especially high-fructose corn syrup, is found in many processed foods, including fast food. Chronic consumption of fructose has been shown to lead to obesity and metabolic dysregulation (high triglycerides and insulin resistance) in humans and accelerate aging in rats. Now, researchers have found that the NAD+ precursor NR may counteract the ill effects of consuming high levels of fructose. 

NR Counteracts Fructose-Induced Fat Buildup and Weight Gain  

To recapitulate a high fructose diet, mice were given water containing 20% fructose daily for 10 weeks. As a result, the mice on the high fructose diet weighed more and had more fat tissue than typical mice, indicating that fructose promotes obesity. However, these indicators of obesity were prevented if the mice were supplemented with 400 mg/kg/day of NR. 

Moreover, the high fructose diet led to higher levels of fat molecules called triglycerides in their blood and liver. However, NR largely prevented this elevation in blood and liver triglycerides. Considering that obesity and high triglycerides accelerate the aging process and contribute to metabolic aging, these findings suggest that NR counteracts fructose-induced metabolic aging and weight gain. 

NR Reignites Fat Burning Potential 

Aside from the fat we are used to, called white adipose tissue, we also have small amounts of fat called brown adipose tissue. Brown adipose tissue has more mitochondria than white adipose and produces a protein called uncoupling protein 1 (UCP1). UCP1 uncouples the process our mitochondria use to generate cellular energy from the actual generation of cellular energy. Namely, UCP1 causes our mitochondria to produce heat instead of cellular energy. 

Cells within white adipose tissue are capable of becoming brown adipose cells, a phenomenon known as browning. Studies have shown that browning can inhibit diet-induced obesity and reverse metabolic dysfunction. However, a high fructose diet is associated with limiting browning, which may contribute to fructose-induced obesity and metabolic aging. For this reason, researchers sought to determine if NR could promote browning. 

To assess browning, the researchers measured the abundance of UCP1 in the fat tissue of mice. They found that mice on a high fructose diet had substantially lower levels of UCP1 than typical mice. However, treatment with NR was shown to prevent this diminishment in UCP1, suggesting that NR promotes browning despite high fructose consumption. Notably, NR was also shown to prevent fructose-induced reductions in SIRT1, a longevity-associated enzyme. 

Previous studies have shown that gut bacteria contribute to browning by secreting short-chain fatty acids that enhance UCP1 function. Supporting this research, the researchers showed that a high fructose diet increases gut bacteria associated with less browning and more obesity. However, NR treatment was shown to increase gut bacteria associated with browning. These findings suggest that NR may counteract obesity and promote browning by altering certain but bacteria. 

Combining Dietary Habits with NR Supplementation 

Whether NR can counteract the pro-aging effects triggered by a high-fructose diet in humans remains to be studied. While previous preclinical studies have supported NR’s ability to counteract obesity, more studies are needed.

Perhaps the best way to avoid the metabolic aging effects of consuming high levels of fructose is to limit fructose consumption. While fruits contain a natural form of fructose, they also contain polyphenols, fiber, vitamins, and minerals and are thus nutrient dense. For this reason, fruits should not be avoided if trying to limit fructose intake. 

In contrast to fruit, many processed foods contain limited vitamins, minerals, fiber, and polyphenols. Moreover, many processed foods lack healthy fats and protein, and are usually laden with poor-quality carbohydrates. These foods can usually be found in the center aisles of grocery stores, because they contain chemical preservatives that prolong their shelf-life. These foods include: 

• Soda 
• Many breads 
• Sweets
• Crackers 
• Cereal 
• Many condiments and dressings 
• Fast food
• Frozen dinners 
• Sweetened juices

Limiting or eliminating the consumption of these processed foods can help prevent metabolic dysfunction, obesity, and accelerated aging. Furthermore, combining a healthier diet void of these foods with NR may potentially aid in the mitigation of accelerated aging.