Researchers at the University of Oulu analyzed information from 2,264 people who were 46 years old and taking part in the Northern Finland Birth Cohort 1966. The team investigated how participants’ usual coffee intake related to circulating metabolites, indicators of cardiometabolic risk, and sex hormone levels.

Coffee Drinkers Had Less Fat and More Muscle

People who consumed more coffee tended to have lower levels of both total body fat and visceral fat, along with greater skeletal muscle mass. These differences appeared even though participants with higher and lower coffee intake had a similar body mass index (BMI).

Higher coffee consumption was also associated with lower circulating concentrations of branched-chain amino acids in both men and women. When chronically elevated, these biomarkers have previously been associated with insulin resistance and a greater risk of developing type 2 diabetes.

Coffee Intake Was Linked to Different Hormone Patterns

Some of the clearest differences appeared among men. Greater coffee consumption was associated with a more favorable glucose-insulin profile, higher levels of total and bioavailable testosterone, and greater concentrations of sex hormone-binding globulin (SHBG). However, free testosterone and the free androgen index were modestly lower.

The hormonal associations were less extensive in women. Higher coffee consumption was mainly associated with increased SHBG and lower measures of free androgens.

“Coffee is consumed by millions of people every day, yet we still know surprisingly little about how it relates to our metabolism and hormones. What stood out in our findings was a distinct hormonal signature that didn’t disappear even after we took into account BMI and lifestyle factors, with several of these associations differing between men and women,” says Luca Verroest, lead author of the study and Doctoral Researcher at the University of Oulu.

Hormones Could Offer a Clue to Coffee’s Health Links

The findings raise the possibility that hormonal pathways could help explain some of the previously observed relationship between coffee consumption and metabolic health. Because the research was observational, however, it cannot establish that drinking coffee directly caused any of the biological differences identified in the study.

The setting also makes the research especially relevant. Finland ranks among the world’s highest coffee-consuming countries, with average annual consumption of approximately 11.8 kilograms (26 pounds) per person.

Researchers say the results offer a starting point for studies designed to determine whether coffee itself produces these biological changes and, if so, which compounds may be responsible. Scientists are currently investigating these questions using animal models, with the longer-term aim of moving toward human intervention studies.

Additional research will be necessary before the findings can be used to shape dietary recommendations.

The study, “Associations of habitual coffee intake with testosterone and cardiometabolic markers: the Northern Finland Birth Cohort 1966 study,” was published in the European Journal of Nutrition.

The findings, published in Current Biology, also show that many types of pollen contain essential amino acids in proportions that do not closely match the needs of bees. Essential amino acids are protein building blocks that animals cannot produce themselves and therefore must obtain through food. The discovery could help farmers, landowners, conservationists and gardeners make better decisions about how to support healthy pollinator populations.

Why Pollen Is Not Always Perfect Bee Food

Bees obtain nearly all of their food from flower nectar and pollen. Nectar supplies mostly sugar, while pollen is their primary source of protein. However, pollen did not evolve mainly as a food reward for pollinators. It is the male reproductive material of plants, so its nutritional composition does not necessarily provide bees with the ideal mixture of nutrients needed for growth, survival and reproduction.

To explore this nutritional mismatch, researchers compared the essential amino acid composition of honeybee tissues with pollen collected from 99 UK flowering plant species representing 26 plant families. They also produced artificial foods designed to mimic either the amino acid composition of different pollens or the composition of honeybee tissues. Newly emerged worker honeybees were then given these diets during controlled laboratory experiments.

Most of the pollen samples turned out to be a relatively poor match for the essential amino acid composition of honeybee tissues. Bees given food that more closely resembled their own tissue composition (rather than pollen) consumed more food, gained more body mass, and chose a diet containing a greater proportion of protein.

One Amino Acid May Help Control Bee Appetite

The researchers suspected that histidine could play an important role in this response. Histidine is an essential amino acid, but bees require it only in relatively small amounts.

To investigate further, the team created artificial diets containing either relatively high or low levels of histidine compared with branched-chain amino acids (such as leucine and isoleucine) that are important for bee growth and development. When the relative amount of histidine was high, the bees reduced their overall food intake. They consumed less protein as well as less carbohydrate.

According to the researchers, this behavior could result from a post-digestive feedback mechanism that prevents bees from taking in potentially harmful quantities of particular amino acids. Instead of simply eating more pollen to compensate for missing nutrients, bees may reduce their intake when another nutrient becomes excessive. Similar responses have been observed in other animals. In rats, for example, excess histidine can be converted into histamine, which activates brain receptors involved in controlling food intake.

Lead author Professor Geraldine Wright (Department of Biology, University of Oxford) said: “Although pollen is often assumed to be a near-perfect food for bees, it is the male gamete of plants and, unlike nectar, it is rarely produced solely as a reward for pollinators. This creates a conflict of interest between the plant and the pollinator.”

Honeybees Create Better Food for Their Young

Honeybees appear to have another way of dealing with the nutritional limitations of pollen, especially when feeding their developing larvae.

Workers gather pollen from a wide variety of flowers and store it inside the hive as ‘bee bread’. Nurse bees eat this material and process its nutrients into glandular secretions, including royal jelly, which are then fed to developing larvae.

The researchers found that bee bread contained a more balanced essential amino acid profile than most individual pollen sources. Royal jelly provided an even closer match to the amino acid composition of bee tissues. The results suggest that combining pollen from different plants and then processing it through nurse bees may allow honeybee colonies to compensate for the nutritional shortcomings of individual pollen sources.

Professor Wright added: “We predict that honeybees have evolved to create glandular secretions which are the perfect food for their larvae, providing them with the ratios of essential amino acids that maximize growth.”

Wild Bees May Face a Greater Nutritional Challenge

This nutritional system is not available to every bee species. Many wild bees, including bumblebees and solitary bees, provide pollen directly to their offspring. In habitats with only a small variety of flowering plants, these bees may have difficulty obtaining the appropriate balance of essential amino acids for both themselves and their developing young.

The results indicate that pollinator-friendly planting schemes may need to consider more than simply providing large numbers of flowers. The nutritional quality of pollen and the diversity of plants producing it may also be important.

Professor Wright said: “Our results suggest that planting for pollinators should not only focus on providing flowers throughout the season, but also on ensuring a diversity of pollen sources. A varied diet may be essential for bees to obtain the right balance of nutrients.”

The research also included scientists from the University of Southampton, Lancaster University, Newcastle University and The Hebrew University of Jerusalem.

Those predators included anacondas, saber toothed mammals, flightless “terror birds” and sebecids, a group of land dwelling relatives of crocodylians. Despite this intense competition, new research indicates that crocodylians occupied an especially important place in the ecosystem and were the most significant group of predators in the region.

“There was so much prey available that mammalian predators couldn’t have eaten it all,” says Oscar Wilson, postdoctoral researcher at the University of Helsinki.

“Our new study shows that crocodylians in particular were the region’s most important predators, especially when it came to hunting large prey.”

A Lost Ecosystem Packed With Giant Prey

The lake shores supported a remarkable variety of herbivores. Giant ground sloths lived alongside glyptodonts, heavily built relatives of armadillos, as well as several groups of ungulates. Ungulates are hoofed mammals, although many extinct South American forms looked very different from familiar animals such as horses and deer.

Among them were astrapotheres (“lightning beasts”) and toxodontids. Some of these ancient ungulates reached enormous sizes and could weigh well over a metric ton.

That abundance of large prey helped support predators that were equally impressive in scale.

The Giant Crocodylian at the Top

The largest known predator in this ecosystem was Purussaurus neivensis, a massive crocodylian related to modern caimans. It grew to about seven meters in length and weighed roughly 1,800 kilograms.

Its immense size placed it near the top of the food chain, where it may have done more than simply hunt individual animals. The new study suggests that Purussaurus could have been influential enough as a predator to affect the size of herbivore populations across the ecosystem.

That possibility gives researchers a glimpse of how powerful giant crocodylians may have been in shaping ancient tropical communities, rather than simply living alongside other large predators.

Fossil Bite Marks Reveal Ancient Predation

To determine which animals were actually attacking prey, researchers examined fossils preserved in museum collections. The evidence comes from bite and tooth marks left on the fossilized remains of herbivores.

These traces are especially valuable because they provide the only direct evidence of interactions between predators and their prey. Rather than relying only on the size, anatomy or presumed hunting abilities of extinct animals, researchers can use the marks left on bones to identify signs of actual feeding or attacks.

The fossils analyzed in the study ranged from 10.5 million to 16 million years old.

“The frequency of marks likely made by Purussaurus suggests that it was an important predator in these tropical ecosystems,” Wilson comments.

The study was published in Journal of Vertebrate Paleontology.