The Two Types of TFA: Industrial vs. Natural
To understand what TFA does to your body, it is important to distinguish between the two primary sources: industrially produced and naturally occurring. Industrially produced TFA (iTFA) are created through the partial hydrogenation of vegetable oils, a process that alters their chemical structure. This process is used to make liquid oils solid at room temperature, giving processed foods a longer shelf life and desired texture. Natural TFA, or ruminant trans fats, are formed in the stomachs of grazing animals like cows and sheep, and are found in small amounts in dairy products and meat. Scientific consensus is clear that iTFA are the most damaging to human health, while the health effects of natural TFA are less conclusive and generally considered less harmful due to their lower intake levels.
Comparison: Industrial vs. Ruminant TFA
| Characteristic | Industrially Produced TFA (iTFA) | Ruminant Trans Fats |
|---|---|---|
| Primary Source | Partially hydrogenated oils in processed foods | Meat and dairy products from animals like cows and sheep |
| Associated Health Risk | High risk, linked strongly to cardiovascular disease | Moderate intake not considered harmful in recent reviews |
| Effect on Cholesterol | Raises LDL ('bad') cholesterol and lowers HDL ('good') cholesterol | Research on cholesterol effects is mixed; some show similar effects but at much lower intake |
| Level of Intake | Can be very high in diets rich in processed and fried foods | Generally low in a typical diet |
| WHO Recommendation | Calls for complete global elimination | No specific call for elimination, though limiting intake is a general healthy eating practice |
Impact of TFA on Cardiovascular Health
One of the most well-documented and severe effects of TFA is their negative impact on the cardiovascular system. The primary mechanism is a harmful alteration of blood cholesterol levels. Unlike other fats, TFA uniquely raises your low-density lipoprotein (LDL) or "bad" cholesterol while simultaneously lowering your high-density lipoprotein (HDL) or "good" cholesterol. This double-hit effect leads to a dangerous buildup of fatty plaque in the arteries, a process known as atherosclerosis. This buildup narrows and hardens the arteries, significantly increasing the risk of heart attack, stroke, and overall cardiovascular mortality.
The Role of TFA in Systemic Inflammation
Beyond cholesterol, TFA consumption is linked to a state of chronic systemic inflammation. Studies have shown that higher levels of TFA in the blood are associated with elevated markers of inflammation, such as C-reactive protein (CRP) and interleukin-6 (IL-6). This chronic, low-grade inflammation is a key driver for numerous health problems and is a significant risk factor for cardiovascular disease. TFA may trigger this inflammatory response by incorporating themselves into cell membranes, which can affect cell signaling pathways. Research also suggests that TFA can promote oxidative stress within blood vessels, further exacerbating the inflammatory damage.
The Link Between TFA and Insulin Resistance
Emerging evidence connects TFA intake with an increased risk of developing insulin resistance, a precursor to type 2 diabetes. Studies, particularly those involving subjects who are already overweight or insulin-resistant, indicate that high TFA intake impairs the body's ability to respond to insulin. This effect has been most dramatically observed with specific trans isomers like conjugated linoleic acid (CLA), which can be diabetogenic. The mechanisms may involve increased oxidative stress, inflammation, and potential disruption of genetic factors that regulate insulin sensitivity. While the effects on lean, healthy individuals may be less pronounced, long-term exposure is a serious concern, particularly for those with a pre-existing risk.
Impact on Adiposity and Weight
Studies suggest that TFA consumption may contribute to weight gain and the accumulation of visceral fat, the dangerous fat stored deep within the abdomen. In a long-term, calorie-controlled study on non-human primates, monkeys on a TFA-rich diet gained more weight and accumulated significantly more abdominal fat than those on a monounsaturated fat diet. These findings suggest that TFA consumption can alter metabolism and fat deposition independent of total calorie intake. High TFA intake has been associated with larger waist circumference in some human observational studies as well.
Common Sources of Trans Fats
Avoiding industrially produced TFA is the most effective way to mitigate their health risks. Common sources of these harmful fats include:
- Baked Goods: Commercially made cakes, cookies, pastries, and biscuits often contain partially hydrogenated oils.
- Fried Foods: French fries, fried chicken, and other deep-fried foods from restaurants or fast-food chains can be cooked in partially hydrogenated oils.
- Snack Foods: Products like crackers, some brands of microwave popcorn, and certain chips may contain iTFA.
- Margarine and Shortening: Stick margarine and vegetable shortening are historically major sources of iTFA.
- Refrigerated Dough: Premade dough for cookies and rolls often relies on iTFA for texture and stability.
To identify iTFA, always check the ingredients list for “partially hydrogenated oil”. The WHO’s REPLACE action package provides a guide for governments and manufacturers to eliminate industrially produced trans fats from the food supply.
Conclusion
In summary, TFA, particularly the industrially produced variety, has a profound and negative impact on the human body. Its damaging effects on cholesterol levels, promotion of systemic inflammation, association with insulin resistance, and contribution to unhealthy fat distribution collectively heighten the risk of chronic diseases. By understanding what TFA does to your body and consciously reducing your intake from processed foods, you can take a significant step toward safeguarding your long-term health and well-being.
