Understanding Hydrogenated Oils and Trans Fats
Hydrogenation is a chemical process that adds hydrogen to liquid vegetable oil, converting it into a solid or semi-solid fat at room temperature. This process was historically favored by food manufacturers because it extended shelf life, improved texture, and was inexpensive. There are two main types of hydrogenated oils: partially and fully hydrogenated. Partially hydrogenated oils (PHOs) were the primary source of artificial trans fats, which have been strongly linked to negative health outcomes. Due to these significant health risks, the U.S. Food and Drug Administration (FDA) banned manufacturers from adding PHOs to foods in 2018, with a full compliance date in 2020.
Fully hydrogenated oils, on the other hand, are highly saturated and contain very little to no trans fat. While they are not the same health risk as PHOs, they are still a form of processed, saturated fat. However, because products with less than 0.5 grams of trans fat per serving can be labeled as having '0 g trans fat', some products may still contain small amounts of PHOs. This is why reading the ingredient list is critical.
Common Sources of High Hydrogenated Oil Content
Even with the ban on PHOs in many countries, vigilance is still required as some products may contain trace amounts or use fully hydrogenated oils. Moreover, different countries may have varying regulations. Here are some of the most common food categories where you might still find hydrogenated oils, particularly fully hydrogenated versions, or products that were historically manufactured with PHOs:
- Commercial Baked Goods: Products like pre-made cakes, cookies, crackers, doughnuts, pastries, and pie crusts often relied on shortening or margarine made with hydrogenated oils for their texture and shelf stability. Even today, many use fully hydrogenated oils as an ingredient.
- Snack Foods: Many packaged snacks, including certain potato chips, microwave popcorn, and some corn and tortilla chips, have historically used hydrogenated oils.
- Fried Foods: Foods fried in commercial deep fryers, such as fast-food french fries, fried chicken, and battered items, may still contain trans fats as a byproduct of repeated heating of the oil. This is in addition to the past use of PHO-based frying oils.
- Spreads and Shortening: Stick margarine and vegetable shortening were once notorious for their high PHO content. While modern versions have been reformulated, some still use fully hydrogenated oils. It's always wise to check the label for any mention of 'hydrogenated oil.'
- Frozen and Refrigerated Dough: Items like frozen pizzas, biscuits, canned dough, and rolls often contain hydrogenated fats to ensure a desirable texture and prolonged freshness.
- Non-dairy Creamers and Toppings: Many creamy, shelf-stable non-dairy products and whipped toppings utilize hydrogenated oils to achieve their consistency and prevent separation.
- Ready-to-Use Frostings: The smooth texture and long shelf life of canned and ready-to-use frostings are often thanks to hydrogenated oils.
Decoding Food Labels: What to Look For
To identify potential sources of hydrogenated oils, consumers must be diligent in reading ingredient lists. While the '0 g trans fat' label is a good sign, it's not a guarantee of zero content.
- Check the ingredients list: The most reliable method is to look for the specific words "partially hydrogenated oil" or "hydrogenated oil" in the ingredients list. The type of oil will also be listed, e.g., "partially hydrogenated soybean oil".
- Understand '0 g Trans Fat': The FDA allows products with less than 0.5 grams of trans fat per serving to be labeled as '0 g trans fat'. For a single serving, this is a negligible amount, but it can accumulate quickly if you consume multiple servings or eat many different foods with trace amounts.
- Look for Alternatives: When shopping, choose products that explicitly state they are made with non-hydrogenated or healthy vegetable oils like olive, avocado, or sunflower oil.
Comparison Table: Partially vs. Fully Hydrogenated Oil
| Feature | Partially Hydrogenated Oil (PHO) | Fully Hydrogenated Oil |
|---|---|---|
| Trans Fat Content | High; primary source of artificial trans fat. | Very little to no trans fat. |
| Safety Status | No longer 'Generally Recognized as Safe' (GRAS) by the FDA; banned in U.S. food supply since 2018. | Considered safe by the FDA, though still a saturated fat. |
| Effect on Heart Health | Raises 'bad' LDL cholesterol and lowers 'good' HDL cholesterol. | Can contribute to an increase in total saturated fat intake. |
| Physical State | Semi-solid at room temperature. | Solid at room temperature. |
| Food Applications | Historically used in many processed and baked goods. | Used to achieve solid texture in some margarines, shortenings, and spreads. |
Conclusion: Making Healthier Choices
While regulations have significantly reduced the prevalence of harmful partially hydrogenated oils in the food supply, consumers must remain aware. The best strategy for a healthier diet is to minimize the intake of ultra-processed foods, which are the main culprits for containing hydrogenated oils and other less-than-ideal ingredients. Cooking more meals from scratch, checking ingredient lists meticulously, and choosing healthier cooking fats like olive or canola oil can help you avoid these processed ingredients and protect your long-term health. By becoming a more informed shopper, you take an active step towards a heart-healthy diet. For further information, the American Heart Association offers dietary guidelines to improve cardiovascular health.
