Added sugar intake might trigger rheumatoid arthritis flareup

Dear Doctors: I stopped eating sugar while I was losing weight last spring and summer. When holiday sweets started showing up, I really indulged. I noticed that hip pain from rheumatoid arthritis, which stopped while I was dieting, came back. Did the sugar do this?

Answer: Studies have identified added sugar as a contributing factor to adverse health condition including Type 2 diabetes, increased body-fat percentage, obesity, cardiovascular disease and metabolic syndrome. 

They’ve also linked added dietary sugar to a higher risk of chronic, low-grade inflammation — chronic being the key.

Low-grade inflammation is actually important. The immune system uses it to fend off potential threats. When everything works properly, immune cells called inflammatory macrophages are alerted to a problem, arrive at the site, perform maintenance and, when their work is done, recede. The departure of the macrophages ends that episode of inflammation.

But sometimes the immune system malfunctions. The macrophages don’t retreat, which means the low-grade inflammation persists. This leads to gradual and ongoing damage.

Chronic, low-grade inflammation plays a role in a range of autoimmune diseases including rheumatoid arthritis, or RA, a chronic inflammatory disorder that can affect joints and also internal organs. Unlike osteoarthritis, in which wear and tear gradually erode joints, the damage from RA is due to chronic, low-grade inflammation — a mistaken response by the immune system, which attacks body tissues. 

The link between excessive sugar and inflammation involves cytokines, which are proteins that modulate inflammation. There are pro-inflammatory cytokines, which trigger an immune response, and anti-inflammatory cytokines, which ease the attack.

When people load up on added sugars, pro-inflammatory cytokines are released. They act as messengers, summoning and urging on immune cells to deflect an invader. The result is inflammation and accompanying physical symptoms including the pain, swelling, stiffness and sensation of heat that are part of RA. 

So it’s possible the sudden and significant increase in sugar played a role in your RA flareup.

With RA, your pro-inflammatory cytokines levels already are high. You went from removing a potential source of inflammation by cutting down on sugar to suddenly adding it in high amounts. 

You don’t have to cut out sugar completely, but it’s wise to return to an anti-inflammatory diet.

Dr. Eve Glazier and Dr. Elizabeth Ko are internists at UCLA Health.