Tag Archives: biological clock

Planet Earth.

Delaying meals can alter the body clock and solve some of that jet lag

Flying in another time zone or working graveyard shifts messes up with our circadian rhythms and ultimately triggers a slew of health problems. Research suggests that one in five people living in Western countries who work at odd hours are putting their lives at risk since their schedule has been linked to obesity, diabetes, heart disease, even cancer. Now, a new study suggests delaying meals can delay metabolic functions governed by the biological clock, too. The work suggests that changing meal times, coupled with light exposure, can help synchronize the ‘clock’ and reduce health problems.

Planet Earth.

Credit: Pixabay.

The notion that our bodies’ biology runs in cycles known as circadian rhythms — also known as sleep/wake cycle or body clock — is becoming more and more established. This complex timekeeping system is controlled by an area of the brain that responds to light, which is why humans are most alert while the sun is shining and are ready to sleep when it’s dark outside.

Humans don’t have a single body clock but a complex network of clocks — as many as there are cells in the body. In mammals, all of these ‘clocks’ are synched with a master clock which beats by the rhythm set in a region of the brain called the suprachiasmatic nuclei (SCN) but also with peripheral clocks found elsewhere, like in various other organs.

It’s the circadian rhythm that ultimately influences sleep-wake cycles, hormone release, body temperature and other important bodily functions. That’s why disrupting this biological clock can come at a hefty cost to our health. Sometimes, though, such situations are inevitable, like in a work setting — what to do?

Previous research has established that there’s a link between nutrition and the circadian rhythm but it’s only recently that this connection has been traced out in broader detail. Researchers at the University of Surrey in the UK recruited ten healthy volunteers who were fed three meals a day at exactly the same times every day for five days. After this initial round, the researchers delayed each meal time by five hours on the following six days. Each daily meal was identical in caloric and macronutrient content and at the end of the six days, the volunteers had to stay awake for 37 hours. They had small, identical snacks every hour for sustenance and dim lighting, in order to measure any change in their circadian rhythms.

These shifts caused a change in the cycle of blood sugar levels.

“A 5-hour delay in meal times causes a 5-hour delay in our internal blood sugar rhythms,” said Jonathan Johnston, one of the authors of the new study published in Current Biology. “We think this is due to changes in clocks in our metabolic tissues, but not the ‘master’ clock in the brain.”

Later, the authors found that the way a certain clock gene released instructions in white fat tissue was delayed after the shift in meal times. Seeing how the ‘master clock’ wasn’t affected, the researchers reckon the delayed meals caused changes in the peripheral clocks without affecting the master clock.

Most jet lag and shift work therapies revolve around controlling light exposure but this sort of intervention seems to work on the master clock only. Changing meals, on the other hand, can help the peripheral clocks come up to speed as well, thus reducing desynchronisation of the body’s clocks.

Keep in mind, though, that this was a small study which needs more validation before we can draw sound conclusions. It does suggest, however, that delaying breakfast for a couple of hours if you flew from London to Moscow can help. Nothing seems to beat a whole week camping under the stars, though.

horvath genetics

Science explains why some people age faster and die younger regardless of lifestyle

horvath genetics

Credit: Steve Horvath

Once each human comes into this world, we’re given a clock whose tick-tock beats to the tune of life. This clock is unique to every person because the pace with which it’s ticking is different, as the clock is wound up by epigenetic changes in the genome. This is the metaphorical conclusion of a groundbreaking study published by biostatisticians at the University of California, Los Angeles. Simply put, some people are destined to biologically age faster than others, even when all things like smoking, eating healthy or exercising are equal. There’s reason to believe these epigenetic changes can be reversed, with far-reaching implications for research in longevity.

Can we wind back the clock?

Steve Horvath, the lead researcher of the study from UCLA, and colleagues, analyzed blood samples collected from 13,000 people, sequenced their genomes, then studied the methyl levels at 353 specific sites. Previously, Horvath’s group showed that the methyl levels of these sites rise and fall according to a specific pattern as the person ages and this pattern is consistent across the whole population.

When the scientists completed their survey, about 2,700 of the initial participants had died. Things like smoking, blood pressure, and body weight were still the best predictive factors for life expectancy but the aging rate was also significant. In other words, some people could live the same healthy lifestyles but die younger or older simply because their internal biological clock is ticking faster or slower.

“Our findings show that the epigenetic clock was able to predict the lifespans of Caucasians, Hispanics and African-Americans in these cohorts, even after adjusting for traditional risk factors like age, gender, smoking, body-mass index and disease history,” said Brian Chen, the study’s first author and a postdoctoral fellow at the National Institute on Aging.

The team found that for 5 percent of the population that ages the fastest, there’s a 50 percent greater average risk of dying at any age. For instance, Horvath mentions a fictitious case study involving two 60-year-old men. Pete is ranked in the top 5 percent of the population that ages the fastest while Joe is classed in the 5 percent of the population that ages the slowest. If both lead stressful lives and smoke tobacco, then Pete has   a 75% chance of dying in the next 10 years compared to a 46% chance for Joe.

Horvath, who is 48 years old, took his own test and found he’s actually five years older, biologically speaking.

The findings published in the journal Aging partially explain why men on average die younger than women. In the U.S., life expectancy for women is 81.2 years; for males, it’s 76.4 years. Horvath says that even by age 5 differences in aging rate can be observed. By the time people are 40 years old, the biological age gap opens up to about 1 to 2 years.

“We must find interventions that prolong healthy living by five to 20 years. We don’t have time, however, to follow a person for decades to test whether a new drug works.” Horvath said. “The epigenetic clock would allow scientists to quickly evaluate the effect of anti-aging therapies in only three years.”

If you’re good with data sets and had your DNA sequenced in the past, there’s a tutorial written by Professor Horvath that will teach you how to calculate your biological age.

Not enough reasons to give up fatty food? Well, it disrupts your biological clock too!

Eating too much fatty food does not only lead to being overweight and related diseases, but it can also disturb the balance of one’s circadian rhythms, which means your 24-hour biological clock will stop working thee way it should.

Dr. Oren Froy and his colleagues of the Institute of Biochemistry, Food Science and Nutrition at the Hebrew University’s Robert H. Smith Faculty of Agriculture, Food and Environment from Jerusalem found a link between a high-fat diet and disturbances of the biological clock after experimenting on mice.

These disturbances can lead to obesity, psychological and sleep disorders and even cancer because the activity of hormones and enzymes involved in metabolism is affected dramatically.

Even though light is the main factor which influences one’s circadian cycle, diet appears to have a strong effect on it too.

The researchers wanted to find out how important diet is for the way adiponectin works, this being a substance which is highly important for metabolism because it increases fatty acid oxidation and promotes insulin sensitivity.

The mice were fed differently, some with highly-fat food, while others received a low-fat diet. This was followed by a fasting day, while adiponectin activity was verified. The mice who had eaten low-fat food had a normal circadian rhythm of life while the others showed a phase delay as the way proteins involved in fatty acid metabolism worked was affected.

The researchers suggest that eating too much fatty food leads to obesity also because it affects the daily rhythm of clock genes. This may also explain the disruption of other systems connected to metabolic diseases, such as blood pressure levels and the sleep/wake cycle.
Source: The Hebrew University of Jerusalem