Trans fatty acids are on the hot search again, is it really impossible to eat one bite?

On May 9, trans fatty acids were on the hot search again!

Screenshot of the web platform

There is news that "a well-known brand of dairy products contains trans fatty acids, which is harmful to health", and many bloggers have reminded parents to "be long-hearted" and not to give it to their children. We can't judge what the brand's products are, but today we can talk about trans fatty acids in our food.

What are trans fatty acids?

Fats are triglycerides formed from fatty acids and glycerol, which also have different names depending on the structure. Trans fatty acids are a type of fatty acid and are an unsaturated fatty acid.

Existing research suggests that the main harm of trans fats is that they significantly increase the risk of cardiovascular disease, as it can increase blood levels of low-density lipoprotein (LDL, or "bad cholesterol") while decreasing levels of high-density lipoprotein (HDL, or "good cholesterol"), leading to an increased risk of arteriosclerosis and heart attack.

As for other effects, such as obesity, cancer, diabetes, growth and development, reproductive health, Alzheimer's disease, and other issues, the evidence is insufficient.

There are also claims that trans fats are deposited in the body and cannot be metabolized, and that it needs to be metabolized in the human body for 51 days, but these claims are actually wrong. In the human body, trans fats are metabolized in the same way as regular fats, and no differences in the metabolic pathways of trans fats in infants, children, adolescents and adults have been found.

What foods contain trans fatty acids?

Trans fatty acids are found in natural foods

Yes, you read that right, trans fatty acids are also found in natural foods, mainly from ruminants such as meat, fat, milk and dairy products of cattle, sheep, etc.

Trans fatty acids are also found in human breast milk. Studies have found that the trans fat content in breast milk accounts for 1%~10% of the fat content of breast milk, such as 7.0±2.3% for American women and 7.19±3.03% for Canadian women.

Hydrogenated vegetable oil

Hydrogenated vegetable oils are a "notorious" source of trans fatty acids. Hydrogenation of vegetable oils is an operation that improves food processing performance by adding hydrogenation to an unsaturated bond that increases the melting point of the oil.

The shortening effect of liquid vegetable oil is not good, but after hydrogenation, it is semi-solid at room temperature, which can meet the requirements of process and taste. The use of hydrogenated vegetable oils can also improve the taste of food, such as crispier cookies and smoother milk tea.

In addition, it is chemically stable, can extend the shelf life, and has a lower cost than animal fats and fats such as natural creams, so hydrogenated oils are widely used in the food industry.

However, vegetable oils, in the case of incomplete hydrogenation, have some double bonds that convert from the natural "cis structure" to the "trans structure", thus making the fats containing them "trans fats". In addition, high temperature and prolonged oil during the frying process of food will also produce a small amount of trans fatty acids.

But in reality, not all hydrogenated oils have trans fatty acids. Only fats and oils that are not completely hydrogenated produce trans fatty acids.

At present, with the development and innovation of food science and technology, the trans fatty acids in edible oil products such as hydrogenated vegetable oil can be well controlled, and alternative products such as non-hydrogenated oil products are also applied.

Is it true that you can't eat trans fatty acids in one bite?

is still the classic saying, "Talking about toxicity aside from dosage is a hooligan". Whether trans fatty acids are harmful to our health depends on how much we eat.

At present, the dietary guidelines of the World Health Organization (WHO), China, the United States and other countries all recommend that the energy supply ratio of trans fats should be less than 1%, which is equivalent to eating about 2.2 grams of trans fats for an adult who needs to consume 8400 kilojoules of energy per day. According to mainland survey data, the average daily trans fat eaten by Chinese is 0.39 grams, which is equivalent to an energy supply ratio of 0.16%, far lower than the WHO's recommended value (less than 1%).

Therefore, as long as you do not consume a lot of foods containing trans fatty acids, the health risk is very low, and you don't need to panic too much about trans fats.

For example, trans fatty acids are naturally found in milk, but they are usually found in small amounts. The trans fat content averaged 0.08 g/100 g for liquid milk, 0.26 g/100 g for milk powder and 0.07 g/100 g for yoghurt.

In other words, a person would need to drink 2.75 kilograms of milk a day to exceed the WHO recommendation.

How to identify food in food

Are there any trans fatty acids?

These two types of foods are usually higher in trans fatty acids

There are two types of foods with high trans fat content, one is natural and margarine, butter, with an average content of 2 g/100 g; The other is vegetable oil, with an average content of 0.86 g/100 g.

The average trans fat content in other foods is generally low, but some products, such as cocoa butter substitute chocolate, french fries/chips, cakes, wafers, and sandwich biscuits, may contain high trans fats due to the use of hydrogenated oils in some products.

I see the list of food ingredients from the meeting

The first thing to look at is the ingredient list on the label of the food. There are many common "names" of hydrogenated oils and fats in the label ingredient list, including hydrogenated vegetable oil, partially hydrogenated vegetable oil, hydrogenated palm oil, hydrogenated soybean oil, vegetable shortening, margarine, non-dairy creamer, cocoa butter substitute, etc. Therefore, when you buy packaged food, if you see these things in the ingredient list, it means that there may be trans fatty acids.

Secondly, you should also look at the nutrition facts list on the label, and you can choose foods that do not contain trans fatty acids or are low in trans fatty acids.

The National Food Safety Standard of China, the General Principles for Nutrition Labeling of Prepackaged Foods, stipulates that if a food ingredient contains or partially hydrogenated oils and fats are used in the production process, the content of trans fatty acids must be indicated in the nutrition facts list of the food label. In other words, if you eat food that doesn't have trans fatty acid content on the label, it generally doesn't contain hydrogenated oils.

The continental standard also stipulates that if the trans fatty acid content in 100 grams of food is less than 0.3 grams, it can be labeled as "0". In other words, if the nutrition facts of your food label indicate the content of trans fatty acids, but the amount is zero, and it may contain trans fatty acids, you should pay attention to your intake.

How to control it in your diet

Trans fatty acid intake?

The key to controlling trans fatty acids is cooking oil

According to the survey, (refined) vegetable oil is the main source of trans fatty acids for Chinese, so to avoid excessive intake of trans fatty acids, we must first pay attention to the appropriate amount of vegetable oil in cooking.

The Dietary Guidelines for Chinese Residents (2022) suggests that the daily intake of cooking oil for adults should be controlled at 25~30 grams, but we actually eat an average of nearly 40 grams per day, and many people exceed 40 grams. Therefore, if you want to control the intake of trans fatty acids, the main contradiction that you must first grasp is to put less oil in stir-frying.

Don't just focus on trans fatty acids and ignore total fat

As a reminder, sometimes we overestimate the health risks of trans fatty acids while ignoring total fat and saturated fat.

Generally speaking, foods with a lot of trans fats are indispensable for total fat and saturated fat. High saturated fat intake increases the risk of atherosclerosis, coronary heart disease, and hypercholesterolemia. Excessive total fat intake also increases the risk of obesity and cardiovascular disease.

You must know that at present, the total fat energy supply ratio of our residents is 34.6%, which has exceeded the health recommendation range (20%~30%), most of which come from cooking oil for stir-frying; Nearly one-third of people also have saturated fat-to-energy ratios that exceed the recommended health range (10%). And our trans fatty acid intake is well below the recommended health range, not at all. Therefore, instead of always worrying about trans fatty acids, it is better to use less stir-fried vegetable oil and eat less fatty meat and fried food.

(Source: Popular Science China)