# Unsaturated oils Category: Foods & Substances When an oil is saturated, that means that the molecule has all the hydrogen atoms it can hold. Unsaturation means that some hydrogen atoms have been removed, and this opens the structure of the molecule in a way that makes it susceptible to attack by free radicals. 9 passages · 1 author · 1997–2006 · Most-cited: [Ray Peat](https://bioenergeticoracle.com/md/voices/ray-peat/index.md) Canonical page: https://bioenergeticoracle.com/concepts/unsaturated-oils ## Synthesis **Unsaturated oils** are fats whose molecular structure lacks hydrogen atoms, creating a chemical openness that makes them *susceptible to attack by free radicals*. [Source 1] Peat argued that this vulnerability initiates **lipid peroxidation**, a chain reaction of oxidative damage that spreads within cells and contributes directly to aging. [Source 2] The toxicity is intrinsic to the **polyunsaturated fat** itself, not a byproduct of industrial processing; these oils are found in high concentrations in seeds like soybean, corn, safflower, canola, and sunflower, and they accumulate in the tissues of animals fed these seeds. [Source 3, 6] Peat identified two evolutionary reasons for their harmfulness. First, plants produce these oils as defensive toxins to block the *proteolytic digestive enzymes* in the stomachs of animals that eat the seeds, which means they fundamentally disrupt protein digestion and all systems evolutionarily derived from it, including thyroid hormone production, clot removal, and immunity. [Source 4, 6] Second, the oils are designed to remain liquid at the low temperatures of early spring germination, but they become highly unstable and spontaneously oxidize when warm and exposed to oxygen inside the body, causing them to go rancid. [Source 4] This oxidative stress damages mitochondria, suppressing the **respiratory enzyme** and uncoupling energy production, which lowers the metabolic rate and creates a hypothyroid state that promotes obesity. [Source 8, 9] Peat noted that the agricultural industry discovered that corn and soy beans had an antithyroid effect that fattened livestock cheaply, and these same oils were subsequently marketed for human consumption. [Source 5, 8] The systemic consequences of excess unsaturated oil consumption include immunodeficiency, inflammation, abnormal clotting, cancer, and brain damage. [Source 2, 5] Peat cited experiments showing that pregnant mice fed unsaturated oil produced offspring with smaller brains and inferior intelligence, while nursing rats fed soy oil incorporated it directly into brain cells, causing visible structural abnormalities. [Source 7, 8] He also emphasized that dietary linoleic acid is required for the development of alcoholic liver damage, and that unsaturated oils promote the formation of **age pigment** (lipofuscin). [Source 7] The oils weaken red blood cell structure through lipid peroxidation, causing premature destruction, and their breakdown products act as *chaotropic* agents that create structural disorder in cell surfaces. [Source 3, 9] Peat rejected the concept of "essential fatty acids" as a misnomer, stating that the body can synthesize its own unsaturated fats when dietary linoleic and linolenic acids are absent. [Source 2, 6] He also dismissed the claim that unsaturated oils are needed for **membrane fluidity**, arguing instead that their affinity for binding to proteins—particularly proteolytic and respiration-related enzymes—accounts for their toxicity, and that saturated fats like those in coconut oil can actually increase fluidity in certain cell types, such as lung alveolar cells. [Source 3, 9] The harm from these oils is governed not by absolute quantity but by the *relationship between them and saturated fats* in the diet. [Source 4] Peat recommended strict avoidance of soybean, corn, safflower, flax, cottonseed, canola, peanut, and sesame oils, and noted that even lard from corn-and-soy-fed pigs is chemically equivalent to vegetable oil and equally toxic. [Source 5, 6] ## People also ask ### How do unsaturated oils cause oxidative damage in the body? Peat argued that their molecular structure lacks hydrogen atoms, making them susceptible to free radical attack, which initiates lipid peroxidation—a chain reaction of oxidative damage that spreads within cells and contributes to aging. ### Why did Peat believe unsaturated oils suppress thyroid function? Peat explained that these oils disrupt proteolytic digestive enzymes, impairing systems evolutionarily derived from them, including thyroid hormone production, while their oxidative stress damages mitochondria and lowers metabolic rate, creating a hypothyroid state. ### What is the relationship between unsaturated and saturated fats in the diet? Peat stated that the harm from unsaturated oils is governed not by absolute quantity but by their relationship with saturated fats, and he recommended strict avoidance of common seed oils while noting that saturated fats like coconut oil can increase membrane fluidity. ## Related concepts - [Albumin](https://bioenergeticoracle.com/md/concepts/albumin/index.md) - [Anemia](https://bioenergeticoracle.com/md/concepts/anemia/index.md) - [Dehydroepiandrosterone (DHEA)](https://bioenergeticoracle.com/md/concepts/dehydroepiandrosterone-dhea/index.md) - [Essential fatty acids (EFA)](https://bioenergeticoracle.com/md/concepts/essential-fatty-acids-efa/index.md) - [Estrogen](https://bioenergeticoracle.com/md/concepts/estrogen/index.md) - [Lipid peroxidation](https://bioenergeticoracle.com/md/concepts/lipid-peroxidation/index.md) ## Cited passages Passage numbers match the `[Source N]` markers in the synthesis above. ### Source 1 — Glossary Ray Peat · Glossary > Unsaturated oils > > When an oil is saturated, that means that the molecule has all the hydrogen atoms it can hold. Unsaturation means that some hydrogen atoms have been removed, and this opens the structure of the molecule in a way that makes it susceptible to attack by free radicals. ### Source 2 — Unsaturated Vegetable Oils: Toxic Ray Peat · Article · 2006 > **Ray Peat:** Immunodeficiency (weakness of the immune system) can take many forms. AIDS, for example, refers to an immunodeficiency which is acquired, rather than inborn. Radiation and vegetable oils can cause acquired immunodeficiency. Unsaturated oils, especially polyunsaturates, weaken the immune system's function in ways that are similar to the damage caused by radiation, hormone imbalance, cancer, aging, or viral infections. The media discuss sexually transmitted and drug-induced immunodeficiency, but it isn't yet considered polite to discuss vegetable oil-induced immunodeficiency. Unsaturated oils: When an oil is saturated, that means that the molecule has all the hydrogen atoms it can hold. Unsaturation means that some hydrogen atoms have been removed, and this opens the structure of the molecule in a way that makes it susceptible to attack by free radicals. Free radicals are reactive molecular fragments that occur even in healthy cells, and can damage the cell. When unsaturated oils are exposed to free radicals they can create chain reactions of free radicals that spread the damage in the cell, and contribute to the cell's aging. Rancidity of oils occurs when they are exposed to oxygen, in the body just as in the bottle. Harmful free radicals are formed, and oxygen is used up. Essential fatty acids (EFA) are, according to the textbooks, linoleic acid and linolenic acid, and they are supposed to have the status of vitamins, which must be taken in the diet to make life possible. However, we are able to synthesize our own unsaturated fats when we don't eat the EFA, so they are not essential. The term thus appears to be a misnomer. ### Source 3 — From PMS to Menopause: Female Hormones in Context Ray Peat · Book · 1997 > **Ray Peat:** One of the stylish ways to promote the use of unsaturated oils is to refer to their presence in "cell membranes," and to claim that they are essential for maintaining "membrane fluidity." As I have mentioned above, it is the ability of the unsaturated fats, and their breakdown products, to interfere with enzymes and transport proteins, which accounts for many of their toxic effects, so they definitely don't just harmlessly form "membranes." They probably bind to all proteins, and disrupt some of them, but for some reason their affinity for proteolytic and respiration-related enzymes is particularly obvious. (I think the chemistry of this association is going to give us some important insights into the nature of organisms. Metchnikof's model that I have discussed elsewhere might give us a picture of how those factors relate in growth, physiology, and aging.) Unsaturated fats are slightly more water-soluble than fully saturated fats, and so they do have a greater tendency to concentrate at interfaces between water and fats or proteins, but there are relatively few places where these interfaces can be usefully and harmlessly occupied by unsaturated fats, and at a certain point, an excess becomes harmful. We don't want "membranes" forming where there shouldn't be membranes. The fluidity or viscosity of cell surfaces is an extremely complex subject, and the degree of viscosity has to be appropriate for the function of the cell. Interestingly, in some cells, such as the cells that line the air sacs of the lungs, cholesterol and one of the saturated fatty acids found in coconut oil can increase the fluidity of the cell surface. In many cases, stressful conditions create structural disorder in cells. These influences have been called "chaotropic," or chaos-producing. ### Source 4 — Unsaturated Vegetable Oils: Toxic Ray Peat · Article · 2006 > **Question:** How are these oils hazardous to your health? > > **Ray Peat:** Ultimately, all systems of the body are harmed by an excess of these oils. There are two reasons for this. One is that the plants produce the oils for protection, not only to store energy for the germination of the seed. To defend the seeds from the animals that would eat them, the oils block the digestive enzymes in the animals' stomachs. Digestion is one of our most basic functions, and evolution has built many other systems by using variations of that system; as a result, all of these systems are damaged by the substances which damage the digestive system. The other reason is that the seeds are designed to germinate in early spring, so their energy stores must be accessible when the temperatures are cool, and they normally don't have to remain viable through the hot summer months. Unsaturated oils are liquid when they are cold, and this is necessary for any organism that lives at low temperatures. For example, fish in cold water would be stiff if they contained saturated fats. These oils easily get rancid (spontaneously oxidizing) when they are warm and exposed to oxygen. Seeds contain a small amount of vitamin E to delay rancidity. When the oils are stored in our tissues, they are much warmer, and more directly exposed to oxygen, than they would be in the seeds, and so their tendency to oxidize is very great. These oxidative processes can damage enzymes and other parts of cells, and especially their ability to produce energy. The enzymes which break down proteins are inhibited by unsaturated fats, and these enzymes are needed not only for digestion, but also for production of thyroid hormones, clot removal, immunity, and the general adaptability of cells. The risks of abnormal blood clotting, inflammation, immune deficiency, shock, aging, obesity, and cancer are increased. Thyroid and progesterone are decreased. Since the unsaturated oils block protein digestion in the stomach, we can be malnourished even while eating well. ### Source 5 — Unsaturated Vegetable Oils: Toxic Ray Peat · Article · 2006 > **Ray Peat:** It's a whole system of promotion, advertising, and profitability. 50 years ago, paints and varnishes were made of soy oil, safflower oil, and linseed (flax seed) oil. Then chemists learned how to make paint from petroleum, which was much cheaper. As a result, the huge seed oil industry found its crop increasingly hard to sell. Around the same time, farmers were experimenting with poisons to make their pigs get fatter with less food, and they discovered that corn and soy beans served the purpose, in a legal way. The crops that had been grown for the paint industry came to be used for animal food. Then these foods that made animals get fat cheaply came to be promoted as foods for humans, but they had to direct attention away from the fact that they are very fattening. The cholesterol focus was just one of the marketing tools used by the oil industry. Unfortunately it is the one that has lasted the longest, even after the unsaturated oils were proven to cause heart disease as well as cancer. I use some of these oils (walnut oil is very nice, but safflower oil is cheaper) for oil painting, but I am careful to wash my hands thoroughly after I touch them, because they can be absorbed through the skin. ### Source 6 — From PMS to Menopause: Female Hormones in Context Ray Peat · Book · 1997 > **Question:** You say vegetable oils are hazardous to your health. What vegetable oils are you talking about? > > **Ray Peat:** Mainly, I'm referring to soybean oil, corn oil, safflower oil, canola, sesame oil, sunflower seed oil, palm oil, and any others that are labeled as "unsaturated" or "polyunsaturated." Almond oil, which is used in many cosmetics, is very unsaturated. Chemically, the material that makes these oils very toxic is the polyunsaturated fat itself. These unsaturated oils are found in very high concentrations in many seeds, and in the fats of animals that have eaten a diet containing them. The fresh oils, whether cold pressed or consumed as part of the living plant material, are intrinsically toxic, and it is not any special industrial treatment that makes them toxic. Since these oils occur in other parts of plants at lower concentration, and in the animals which eat the plants, it is impossible to eat a diet which lacks them, unless special foods are prepared in the laboratory. These toxic oils are sometimes called the "essential fatty acids" or "vitamin F," but this concept of the oils as essential nutrients was clearly disproved over 50 years ago. Linoleic and linolenic acids, the "essential fatty acids," and other polyunsaturated fatty acids, which are now fed to pigs to fatten them, in the form of corn and soy beans, cause the animals' fat to be chemically equivalent to vegetable oil. In the late 1940s, chemical toxins were used to suppress the thyroid function of pigs, to make them get fatter while consuming less food. When that was found to be carcinogenic, it was then found that corn and soy beans had the same antithyroid effect, causing the animals to be fattened at low cost. The animals' fat becomes chemically similar to the fats in their food, causing it to be equally toxic, and equally fattening. These oils are derived from seeds, but their abundance in some meat has led to a lot of confusion about "animal fats." Many researchers still refer to lard as a "saturated fat," but this is simply incorrect when pigs are fed soybeans and corn. ### Source 7 — Oils in Context Ray Peat · Article · 2006 · https://raypeat.com/articles/nutrition/oils-in-context.shtml > Until the research with animals has produced a better understanding of the effects of unsaturated oils, experimenting on human babies seems hard to justify. > > Marion Diamond, who has studied the improved brain growth in rats given a stimulating environment (which, like prenatal progesterone, produced improved intelligence and larger brains), observed that in old age the "enriched" rats' brains contained less lipofuscin (age pigment). [73] It is generally agreed that the unsaturated oils promote the formation of age pigment. The discovery that stress or additional cortisone (which, by blocking the use of glucose, forces cells to take up more fat) causes accelerated aging of the brain [74] should provide new motivation to investigate the antistress properties of substances such as the protective steroids mentioned above, and the short-chain saturated fats. > > Essential for Liver Damage: Both experimental and epidemiological studies have shown that dietary linoleic acid is required for the development of alcoholic liver damage. [75] Animals fed tallow and ethanol had no liver injury, but even 0.7% or 2.5% linoleic acid with ethanol caused fatty liver, necrosis, and inflammation. Dietary cholesterol at a level of 2% was found to cause no harm, [76] but omitting it entirely from the diet caused leakage of amino-transferase enzymes. This effect of the absence of cholesterol was very similar to the effects of the presence of linoleic acid with ethanol. > > Obesity: For many years studies have been demonstrating that dietary coconut oil causes decreased fat synthesis and storage, when compared with diets containing unsaturated fats. More recently, this effect has been discussed as a possible treatment for obesity. [77] The short-chain fats in coconut oil probably improve tissue response to the thyroid hormone (T3), and its low content of unsaturated fats might allow a more nearly optimal function of the thyroid gland and of mitochondria. A survey of other tropical fruits' content of short and medium chain fatty acids might be useful, to find lower calorie foods which contain significant amounts of the shorter-chain fats. > > Other Problem Areas: The presence of palmitate in the lung surfactant phospholipids [78] suggests that maternal overload with unsaturated fats might interfere with the formation of these important substances, causing breathing problems in the newborn. ### Source 8 — From PMS to Menopause: Female Hormones in Context Ray Peat · Book · 1997 > **Ray Peat:** The people there are lean, and recently it has been observed that the women there have none of the symptoms we commonly associate with the menopause. By 1950, then, it was established that unsaturated fats suppress the metabolic rate, apparently creating hypothyroidism. Over the next few decades, the exact mechanisms of that metabolic damage were studied. Unsaturated fats damage the mitochondria, partly by suppressing the respiratory enzyme, and partly by causing generalized oxidative damage. The more unsaturated the oils are, the more specifically they suppress tissue response to thyroid hormone, and transport of the hormone on the thyroid transport protein. Plants evolved a variety of toxins designed to protect themselves from "predators," such as grazing animals. Seeds contain a variety of toxins, that seem to be specific for mammalian enzymes, and the seed oils themselves function to block proteolytic digestive enzymes in the stomach. The thyroid hormone is formed in the gland by the action of a proteolytic enzyme, and the unsaturated oils also inhibit that enzyme. Similar proteolytic enzymes involved in clot removal and phagocytosis appear to be similarly inhibited by these oils. Just as metabolism is "activated" by consumption of coconut oil, which prevents the inhibiting effect of unsaturated oils, other inhibited processes, such as clot removal and phagocytosis, will probably tend to be restored by continuing use of coconut oil. Brain tissue is very rich in complex forms of fats. The experiment (around 1978) in which pregnant mice were given diets containing either coconut oil or unsaturated oil showed that brain development was superior in the young mice whose mothers ate coconut oil. Because coconut oil supports thyroid function, and thyroid governs brain development, including myelination, the result might simply reflect the difference between normal and hypothyroid individuals. ### Source 9 — Coconut Oil Ray Peat · Article · 2006 · https://raypeat.com/articles/articles/coconut-oil.shtml > Therefore, shifting from unsaturated fats in foods to coconut oil involves several anti-stress processes, reducing our need for the adrenal hormones. Decreased blood sugar is a basic signal for the release of adrenal hormones. > > Unsaturated oil tends to lower the blood sugar in at least three basic ways. It damages mitochondria, causing respiration to be uncoupled from energy production, meaning that fuel is burned without useful effect. It suppresses the activity of the respiratory enzyme (directly, and through its anti-thyroid actions), decreasing the respiratory production of energy. And it tends to direct carbohydrate into fat production, making both stress and obesity more probable. > > For those of us who use coconut oil consistently, one of the most noticeable changes is the ability to go for several hours without eating, and to feel hungry without having symptoms of hypoglycemia. > > One of the stylish ways to promote the use of unsaturated oils is to refer to their presence in "cell membranes," and to claim that they are essential for maintaining "membrane fluidity." As I have mentioned above, it is the ability of the unsaturated fats, and their breakdown products, to interfere with enzymes and transport proteins, which accounts for many of their toxic effects, so they definitely don't just harmlessly form "membranes." They probably bind to all proteins, and disrupt some of them, but for some reason their affinity for proteolytic and respiration-related enzymes is particularly obvious. (I think the chemistry of this association is going to give us some important insights into the nature of organisms. Metchnikof's model that I have discussed elsewhere might give us a picture of how those factors relate in growth, physiology, and aging.) > > Unsaturated fats are slightly more water-soluble than fully saturated fats, and so they do have a greater tendency to concentrate at interfaces between water and fats or proteins, but there are relatively few places where these interfaces can be usefully and harmlessly occupied by unsaturated fats, and at a certain point, an excess becomes harmful. We don't want "membranes" forming where there shouldn't be membranes. > > The fluidity or viscosity of cell surfaces is an extremely complex subject, and the degree of viscosity has to be appropriate for the function of the cell. _Generated 2026-07-20 from the Bioenergetic Oracle corpus._