Choosing the right cooking fat affects more than flavor. It shapes digestion, nutrient absorption, toxin exposure, and long-term metabolic health. Over the last few years, many social media influencers have framed tallow, butter, and ghee as “ancestral” solutions to the seed oil panic. But new data shows a different picture. When you look at human physiology, history, and actual lab research, olive oil stands out as the cleaner, safer, and more evidence-backed option.
A 2024 study published in Environmental Sciences Europe by Li et al. gives the strongest mechanistic evidence so far. The researchers used a validated in vitro digestive model to measure how much heavy metal becomes bioaccessible when bile enters the small intestine. The results were clear. Copper bioaccessibility jumped up to 66 percent in the intestinal phase because bile salts dissolved more of the metal and formed metal-bile complexes. The authors stated that bile salts act as biosurfactants that free heavy metals from the solid phase and hold them in solution. Once solubilized, these metals are much easier for the intestinal wall to absorb.
Why does that matter for your choice of cooking fat? Because diets rich in saturated animal fats stimulate significantly higher bile secretion. Tallow, butter, ghee, and similar fats require aggressive emulsification. When bile output rises, the intestine becomes a more efficient solvent system for lipophilic compounds and metal ions. The more bile you produce, the more heavy metals become bioaccessible, and the more your body behaves like a sponge. This is not speculation. It is the actual mechanism demonstrated in the Li et al. study. More bile creates more dissolved heavy metals. Dissolved metals are the fraction that crosses into the bloodstream.
Olive oil behaves differently. It is high in monounsaturated fat, low in saturated fat, and does not require the same bile intensity. That is why olive oil digests cleanly and gently. You get polyphenols, antioxidants, and stable fatty acids without triggering high bile release that increases metal solubility in the gut.
This is one of the areas where the modern seed oil panic has pushed people into the wrong direction. Frightened by industrial oils, many people swing all the way to tallow or large amounts of butter. The assumption is that animal fats are “ancestral,” natural, and historically normal. Except they weren’t.
Most of the world’s physiological issues began after the agricultural revolution, when stored animal fats became survival tools. Before agriculture, humans did not have reliable access to buckets of tallow, clarified butter, cheese vats, or any of the high saturated fat products that exist today. People ate what they could hunt or gather. That often meant leaner cuts, plant fats, nuts, seeds, olives, and seasonal game. Rendering down kilograms of hard fat into daily household cooking fuel is a post-agricultural behavior, not an evolutionary default.
Even in Rome, which people often imagine as a butter-and-milk society, the reality was very different. Romans did not drink raw milk as a daily beverage. They did not cook with butter. They did not fry food in animal fat as a routine habit. They relied on cheeses because cheese was stable, transportable, and far less likely to spoil. Butter remained a fringe product in the northern provinces. Olive oil dominated the culinary world because it was reliable, stable, and clean. That pattern persisted through the Mediterranean for thousands of years.
Our modern relationship with dairy is even more recent. Homogenized milk is barely a century old. Industrial butter is a product of mechanization and refrigerated supply chains. None of these foods existed in the form people consume today when human physiology developed. The idea that tallow or butter represents a timeless ancestral baseline is simply not true.
Meanwhile, olive oil has been a staple for thousands of years without the digestive burden that animal fats impose. It delivers energy without forcing the liver to flood the intestine with bile. It delivers flavor without the metal-solubilizing side effects described in the Li et al. study. It also comes with naturally low heavy metal levels because olives grow on trees, not in contaminated soil layers that concentrate metals in root systems.
Modern health advice should be rooted in evidence, not nostalgia. If the goal is reducing toxins, heavy metals, aldehydes, and unnecessary oxidative stress, then the cleanest path forward is simple: choose fats that require the least metabolic cost to digest. Olive oil fits that profile better than any common cooking fat.
The seed oil panic may have made people afraid to use anything plant-based, but not all plants are the same. Olive oil is not soybean oil. It is not rapeseed. It is not corn oil. It is a single-origin fruit oil with a long cultural and physiological track record. When scientific studies show that bile increases metal solubility and animal fats increase bile demand, the conclusion becomes straightforward. A daily fat should be clean, stable, and gentle on digestion.
Olive oil checks every box.
If you want a cooking fat that works with your physiology instead of pushing your digestion into overdrive, start with something simple. Choose an oil that digests cleanly, supports metabolic balance, and does not increase the intestinal bioaccessibility of metals you would rather avoid.
Selo Olive Oil comes from a single Croatian grove and is produced entirely at the source it grows on. It is high in oleic acid, stable under heat, and made with the same methods families along the Adriatic have relied on for generations.