Is Hydrogenated Oil Unhealthy? Which Foods Contain It?

All fats are made of a chain of carbon atoms with some hydrogen atoms attached. Hydrogenated oils are not the healthiest, so you should eat them in moderation.

If you're trying to eat a healthy diet, you need to know about good and bad fats. Is hydrogenated oil a healthy option? The answer may surprise you.  

Fats are chemical compounds, and their structure determines how they act and whether they are healthy or unhealthy. All fats are made of a chain of carbon atoms with some hydrogen atoms attached. There are differences in the length of the carbon chain, though, as well as the shape of the chain and the number of hydrogen atoms. 

Consequently, fats are either saturated or unsaturated. Saturated fats incorporate more hydrogen atoms and are usually solid. Unsaturated fats have fewer hydrogen atoms and are usually liquid. 

In the late 1800s, chemists found they could alter the quality of fat by adding more hydrogen to it. This process could turn liquid vegetable oil into a solid product that behaved like butterfat. This hydrogenated fat had a longer shelf life and was easier to transport and store.

Food manufacturers created two kinds of hydrogenated oil: partially hydrogenated oils {PHOs} that were semi-solid and fully hydrogenated oils {HOs) that were solid. 

After scientists linked saturated fat with heart disease, they thought that hydrogenated oils might be healthy alternatives to butter or lard. It turned out that they were wrong, though – at least about partially hydrogenated oils. 

You may have heard of trans fats. Researchers have discovered that trans fats are generally the worst fats for human health, and when food manufacturers manufactured partially hydrogenated oils, they were creating trans fats.

Small amounts of trans fats occur naturally in food, especially in beef and dairy products. However, for years, people got most of their trans fat from the PHOs in products like margarine, baked goods, and snack foods. Many restaurants used PHOs in their deep fat fryers as well.

Starting in the 1980s, researchers began looking at the impact of trans fats on health. They found that they:

• Raise LDL ("bad") cholesterol
• Lower HDL, the "good" cholesterol
• Interfere with the function of the endothelial cells that line blood vessels
• Lead to inflammation
• Increase the risk of heart attack 

Is it true that trans fats have been banned?

It's not 100% accurate to say that trans fats have been banned. The Food and Drug Administration (FDA) has outlawed artificial trans fats like PHOs. In 2006, the agency began requiring food companies to include trans fat information on their nutrition labels. In 2015, the FDA ruled PHOs were no longer "generally recognized as safe" and gave manufacturers a deadline to remove them from their products. 

Fully hydrogenated oils do not contain trans fats and have not been banned. However, they are saturated fats, and health experts recommend that you limit your intake of saturated fats to less than 10% of your total caloric intake. 

Saturated fats occur in:

• Meat and other animal products
• Most dairy products
• Palm oil, palm kernel oil, and coconut oil
• Fully hydrogenated oils

For the best health outcomes, consider foods high in unsaturated fat, including:

• Olive oil and other vegetable oils
• Nuts
• Seeds
• Fish

That being said, another key to better health in many cases is to generally reduce your total intake of fats. The American Heart Association recommends getting less than 30% of your calories from fat. Currently, Americans average about 40%. 

Fortunately, hydrogenated oils may not be as unhealthy as some other saturated fats. The process of hydrogenating oil creates stearic acid, which is a saturated fat, but your body changes stearic acid to oleic acid, which is monounsaturated. 

In their search for a trans fat replacement, some food manufacturers have turned to hydrogenated oils. They use a chemical process called interesterification to combine hydrogenated oils with polyunsaturated oils. By adjusting the proportions, they can create products with the consistency they need. These manufacturers believe such "interesterified" oils will prove healthier than palm oil and other highly saturated oils.

Although scientists have, to date, linked no health issues to interesterified oils, they say there are still many gaps in their knowledge. Perhaps remembering the lessons learned with trans fats, they warn that we need more research to study how the body handles interesterified oils.  

Although hydrogenated oils are not as bad for you as trans fats, they are often included in "junk" foods that you shouldn't be eating too often, such as:

• Commercial baked goods
• Fast food
• Fried foods

If you are wondering whether a prepared food contains hydrogenated oil, take a look at the label. Foods with nutritional labels must list hydrogenated oil if it is an ingredient. 

Instead of recommending a low-fat diet, many health experts now say it's the type of fat you eat that matters most. Trans fats have some of the most harmful effects, but you shouldn't encounter too many now that they're widely prohibited. The "best" fats are unsaturated. Saturated fats like hydrogenated oils fall somewhere in between — so feel free to use them in moderation.