The debate about whether vegetable or animal fats are better is a recurring one, but does it make sense? We tell you everything you need to know about both types of fat and find out if one is better than the other.
Fats, in general, have an unbeatable bad reputation; possibly because there is no other nutrient that provides us with more calories. However, and apart from their energy value, their presence in our diet is essential. Not even the advent of sugar as the hypothetical horseman of the dietary Apocalypse has been able to dislodge the bad reputation that “fat” has had for a century and a half.
At the end of the 19th century, when the foundations of nutrition as an emerging science began to be laid, fat was given its first bad name: it was – and still is – the macronutrient that provides the most calories, and by a long way: one gram of fat provides 9 kcal, compared to 4 kcal/g of carbohydrates and proteins, or 7 kcal/g of alcohol. Obesity problems, non-existent among the general population until then, began to rear their ugly heads and it was too tempting not to blame fats due to their high energy density. With the already indelible stigma of being the main cause of obesity, in the mid-20th century, certain scientific findings served as a metaphorical death knell for the image of fats and, once again, they were put in the eye of the storm of a new epidemic: cardiovascular diseases.
It has taken almost 100 years for the spearhead of nutrition as a science – no longer emerging, but consolidated – to open our eyes to several realities that have little or nothing to do with the underlying prejudices about fats among the general population. So, today, we have assumed that:
1. That low-fat diets have the worst prognosis when it comes to losing weight ;
2. that not all fats are equal, it will depend on their physical-chemical characteristics and the food matrix that accompanies them and;
3. that there are food sources that, being rich in fat, are related to better health prognoses.
Thus, very generally and with certain exceptions that will be detailed below, fats present in foods of plant origin are associated with better health prognoses, and fats from animal foods with worse ones. Is this really the case?
Oils, fats, and lipids: are they the same?
We colloquially call “fats” as a generic term for what we should actually call “lipids”. Lipids are organic molecules that, while insoluble in water, are soluble in organic solvents. Being rigorous with nomenclature, lipids include various families of molecules, including fatty acids, waxes, sterols, fat-soluble vitamins A, D, E, and K, monoglycerides, diglycerides, and triglycerides.
Among all these families, the one that stands out is the fatty acid family, molecules composed only of carbon, oxygen, and hydrogen atoms. These fatty acids have two characteristics that ultimately determine their effect on health:
- The length of the carbon atom chain: so we will have short, medium, and long-chain fatty acids.
- The number of double bonds in that chain: If there are no double bonds, we will say that they are called saturated fatty acids, if there is one double bond, monounsaturated, and if there are two or more double bonds, polyunsaturated.
The chain length and the presence and number of double bonds will not only influence the health prognosis and lipid profile of diners, these characteristics will also significantly condition the physicochemical qualities of fatty acids. Longer chain fatty acids will have higher melting points (remaining solid at higher temperatures than those with a short chain); and the presence of double bonds lowers the melting point so that those with more double bonds (unsaturations) will remain fluid at lower temperatures, compared to those that are more saturated (without double bonds) that will remain solid at higher temperatures.
These characteristics are important since we call “fats” those lipids that remain solid at room temperature (something typical of foods of animal origin) and “oils” those lipids that remain liquid and which is usually a characteristic of foods of plant origin.
Types of fats
Whether of animal or plant origin, different foods have a “profile” of fatty acids that usually define them. This means that there will always be a certain type of fatty acid that is more abundant than any of the others. Because we must not forget that, in all cases, whether the lipids come from foods of animal or plant origin, they will always consist of a more or less diverse and more or less complex mixture of different fatty acids. But there will always be one that is the majority and that, therefore, characterizes it. This is better understood with the following examples.
What are animal fats?
Animal fats are those lipids that are found in foods of animal origin. As you may have noticed, their characteristic is that in most cases they are solid fats. This means that there will be a considerable proportion of saturated and long-chain fatty acids. However, remember that there are no pure lipids composed of only one type of fatty acid. Thus, and depending on the specific food, there will surely also be a certain amount of monounsaturated and polyunsaturated fatty acids. Among the best-known animal fats we find:
- Butter: in which saturated fatty acids stand out, but in this case short chain (characteristic of whole dairy products).
- Tallow or beef fat: it has a high proportion of saturated and long-chain fatty acids, so much so that it is one of the fats with the highest melting point (around 40 ºC). This characteristic, and beyond its culinary uses, has long led to the use of this raw material as the main ingredient in certain high-quality soaps (typically for shaving).
- Bacon: Although the proportion of fat in what is called bacon or pancetta is high, it is actually a cured meat derivative from the abdominal region of the pig that includes its skin and a certain proportion of muscle. Although the fatty part stands out for the presence of saturated fatty acids, it also has a higher presence of oleic acid, a monounsaturated fatty acid, compared to the fat of other animal species.
- Fish oils: note that even though they are of animal origin, in the case of fish we often refer to its oils rather than its fat, and the reason is none other than the high presence of polyunsaturated fatty acids in these lipids, many of them from the omega 3 family, which ends up in a liquid product at room temperature.
What are vegetable oils?
In the case of vegetables, when their lipid fraction is extracted it is usually liquid since unsaturated fatty acids are abundant, whether mono or polyunsaturated, which is why, in general, we speak of oils rather than fats.
- Olive oils: from virgin oils (whether extra virgin or not) to olive-pomace oils, including olive oils (nothing more), the fatty acid that characterizes them is oleic acid. This is a common and identical characteristic for all of them. In fact, according to the commercial standard that regulates these oils, they must all contain a minimum of 55% and a maximum of 83% of oleic acid. As you can imagine, the rest of their composition will belong to other fatty acids, including, of course, a certain but small amount of saturated fatty acids.
- Avocado oil: once again, oleic acid is the main ingredient in this type of refined oil, which also stands out for its very low proportion of saturated fatty acids.
- Sunflower oil: another refined oil in which the proportion of polyunsaturated fatty acids from the omega 6 family is the main ingredient.
- Rapeseed oil: a further refined oil (like 98% of all vegetable oils consumed in the world) whose composition includes omega 3 and 6 fatty acids, and a low proportion of saturated fatty acids.
- Coconut and palm fats: in both cases, and unlike the previous oils, we are dealing with products that are particularly rich in saturated fatty acids and, therefore, both products tend to be more or less solid at room temperature, although in the case of coconut fat the amount of saturated fatty acids is even higher. Thus, and as fashionable as it may be (especially coconut fat), both would be options far from the most up-to-date dietary recommendations.
What type of fat is better, animal or vegetable?
I know you want a dichotomous answer. But there isn’t one. Let me explain.
Scientific knowledge on nutrition, and more specifically on fats and oils, has changed substantially in the last two decades, although this knowledge takes time to permeate among consumers. We come from a “nutrient-centric” and dichotomous environment. We have gone from “with fat = bad and without fat = good” to “saturated fats = bad and unsaturated fats = good”.
Today, leaving aside general and simplistic recommendations, the message should be: “focus on food and not on its nutrients.” Thus, and in the words of one of the most relevant epidemiologists in the field of nutrition, Dariush Mozzaffarian, we should leave behind dietary recommendations based on simplistic groupings of nutrients that are minimally related by the same chemical characteristic (in this case, being saturated or unsaturated fatty acids) and focus all recommendations on advice based on food. The big problem with having a nutrient-centric perspective — versus having a food-centric one — comes from knowing that this approach is usually used by the industry to create confusion in consumers who live completely influenced by the media.
In the most practical sense possible and knowing that most of the readers of this article, it is necessary to put emphasis on the use of olive oils – both for dressing and cooking -; to reduce the presence of foods of animal origin, including fish about three times a week, preferably one of them blue (or fatty) and incorporate nuts and seeds (natural or roasted) in our recipes and snacks. At the same time, we should avoid ultra-processed foods and some options that, although fashionable, such as coconut oil or fat, do not make any sense in relation to health.