Higher blood caffeine levels linked to lower obesity and osteoarthritis risk

Medical News Today Article By Corrie Pelc on March 5, 2024 — Fact checked by Hannah Flynn

According to the latest research, more than 1 billion people around the world — both adults and children — have obesity.

Obesity can increase a person’s risk for several health problems, including joint conditions such as osteoarthritis. This is because when a person carries too much weight, it puts additional strain on the knees, hips, and ankles.

Now, researchers from Imperial College London in the United Kingdom and from the University of Copenhagen in Denmark have found that higher levels of caffeine in the blood over a long period may help protect the body against both obesity and joint disease.

The study recently appeared in the journal BMC Medicine

Why study caffeine in relation to obesity, joint health?

Dr. Dipender Gill, a clinician scientist at Imperial College London and lead author of this study, told Medical News Today they decided to study the effect of caffeine on obesity and joint health because caffeine is widely consumed, and they believe it important to better understand its broad effects on health.

For this study, Dr. Gill and his team focused on circulating caffeine in the body.

“This is the amount of caffeine circulating in the blood and is thus pharmacologically active to affect bodily functions,” he explained.

Additionally, the researchers looked at genetic variants related to caffeine metabolism and how that may affect and break down circulating caffeine levels in the blood, also known as plasma caffeine.

“The use of large-scale human genetic data enabled us to provide rapid and cost-effective clinically relevant insight into the effects of plasma caffeine on a broad range of traits and diagnoses,” Dr. Loukas Zagkos, honorary research associate in molecular epidemiology at the Imperial College London and co-first author of this study told MNT.

Genetic data confirm potential protective effect of caffeine

For this study, Dr. Gill and his team first created a weighted genetic risk score (GRS) for plasma caffeine using two genetic variants independently associated with plasma caffeine levels.

The GRS was then used to conduct a phenome-wide association study (PheWAS) featuring 988 clinical traits recorded in the U.K. Biobank related to circulating caffeine levels.

From there, the researchers used a Mendelian randomization analysis to figure out the potential mechanisms underlying the effects of plasma caffeine on previously reported and novel traits.

Scientists also obtained genetic data for plasma caffeine from previous genome-wide association studies (GWAS) of about 9,900 people, mainly Europeans between the ages of 47 and 71. They also received genetic information for osteoarthrosis and osteoarthritis, as well as body mass index details.

Dr. Héléne Toinét Cronjé, a researcher at the University of Copenhagen and co-first author of this study explained to MNT:

“I think the most important aspect of this work is that it allowed us to reframe some of the previous observational findings around caffeine and health outcomes by investigating blood levels of caffeine as opposed to caffeine consumption behavior and doing so through the Mendelian randomization method which uses randomly allocated genetic variation to investigate the causal relationship between an exposure and outcome.”

“This allowed us to circumvent many of the confounding factors that limit observational research such as not knowing whether the effect is specific to caffeine or represents other compounds included in caffeinated products consumed,” Dr. Toinét Cronjé added.

How much caffeine is healthy?

MNT also spoke with Dr. Mir Ali, a bariatric surgeon and medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, CA, about this study.

Dr. Ali said he was not surprised by its results: “I have seen similar studies before showing that caffeine is helpful with weight loss, but it was good to have another confirmation of that.”

When asked how much caffeine a person should consume to potentially lower their obesity or joint health risk, Dr. Ali said some studies have shown that 3 milligrams (mg) of caffeine per kilogram (kg) of body weight is sufficient.

“So somebody who’s about 70 [kg] — that’s 154 lbs [pounds] — would need about 210 [mg] of caffeine, which is a little more than 2 cups of coffee,” he detailed. “I’ve seen that range anywhere from 200 to 400 [mg] a day.”

However, Dr. Ali advised it is also crucial to remember that everyone responds to caffeine differently.

“[For] some people it gives them energy, [for] other people it makes them anxious or jittery,” he continued. “So you have to take that into consideration when somebody’s trying caffeine.”

Read full article here.