PUFA: What Foods Have It, Which to Avoid, and How I Got It Out of My Diet

PUFA stands for polyunsaturated fatty acids. They are the fats with more than one double bond: omega-6, mostly linoleic acid, and omega-3.

The more double bonds a fat has, the less stable it is. It reacts with oxygen easily, in the bottle, in the pan and in your body.

That is why I keep PUFA as low as I can. Here is where it hides, what I eat instead, and what the evidence says on both sides.

What foods are PUFA?

The biggest source by far is seed oil. These are approximate shares of linoleic acid, from standard food composition tables:

• Safflower, grapeseed, sunflower oil: about 65 to 75%. High-oleic versions are much lower.
• Corn, cottonseed, soybean oil: about 50 to 55%.
• Sesame oil: about 40%.
• Peanut oil: about 30%.
• Canola oil: about 20%, plus about 10% omega-3.
• Olive oil and lard: about 10%. Lard varies with what the pig ate.
• Butter and beef tallow: about 2 to 3%.
• Coconut oil: about 2%.

Then come the foods made with those oils, and the foods that are naturally high in PUFA:

• Mayonnaise, salad dressings and most sauces.
• Chips, crackers and packaged snacks.
• Anything deep fried, especially in restaurants.
• Margarine and vegetable shortening.
• Store-bought baked goods.
• Nuts, seeds, peanut butter and tahini.
• Chicken skin and pork fat, because those animals are fed corn and soy.
• Fatty fish and fish oil capsules, which are omega-3 PUFA.

"Vegetable oil" on a label almost always means soybean or canola.

How much more we eat now

• Between 1909 and 1999 the estimated consumption of soybean oil in the United States rose more than 1,000-fold. Linoleic acid went from 2.79% to 7.21% of calories. (Blasbalg 2011)
• It shows up in our tissue. A review of American studies found that linoleic acid in body fat rose by 136% over the last half century, in step with intake. (Guyenet 2015)

The fat you eat becomes the fat you are made of.

Why I avoid it

• The old heart trials. When the lost data from the Sydney Diet Heart Study was recovered, the men who replaced saturated fat with linoleic acid, from safflower oil and margarine, had higher rates of death from all causes and from heart disease. (Ramsden 2013)
• The Minnesota Coronary Experiment. Its recovered data showed that swapping saturated fat for linoleic acid lowered cholesterol, but a pooled analysis found no benefit for death from heart disease or from any cause. (Ramsden 2016)
• Insulin resistance in rats. Young rats were fed diets with 19 g of soybean or canola oil against a 7 g control for 60 days. Both got more belly fat, and the canola group's insulin resistance index rose by 78%. (Costa 2011)
• Stress hormones. An oxidized product of linoleic acid stimulated rat adrenal cells to make more corticosterone, their version of cortisol. (Bruder 2003)

My own view goes further than those studies. I think PUFA in the cell membrane makes the cell weaker and less able to burn glucose, and that this is behind a lot of low thyroid, bad skin and easy sunburn. I used to burn within an hour. I do not anymore.

Ray Peat wrote about this for decades. What he said, with the studies he cited, is in Ray Peat on PUFA.

The honest part

• Large observational studies point the other way. In a meta-analysis of cohorts, people who ate the most linoleic acid had a 15% lower risk of heart disease events and a 21% lower risk of heart disease death. (Farvid 2014)
• A meta-analysis of randomized trials found that eating more linoleic acid did not significantly change inflammatory markers in the blood. (Su 2017)
• Mainstream nutrition science classes linoleic acid and alpha-linolenic acid as essential fats and advises replacing saturated fat with them.
• The rat and cell studies above do not prove the same thing happens in people.

So the science is not settled in my direction. I avoid PUFA because of the recovered trial data, the physiology and how I feel without it. You should know the other side before you decide.

PUFA foods to avoid, and what to use instead

• Cooking oil: coconut oil, butter, ghee or beef tallow instead of seed oils.
• Salad dressing: vinegar, salt and a little olive oil instead of bottled dressing.
• Mayonnaise: make it with a low-PUFA oil or skip it.
• Snacks: fruit, cheese, dark chocolate or potatoes cooked at home instead of chips and crackers.
• Nut butter: honey, jam or butter.
• Fried food out: order grilled or baked, and ask what it is cooked in.
• Chicken and pork: choose lean cuts and remove the skin, or eat beef and lamb.
• Fish oil: skip it. Eat shellfish or lean white fish.

How to reduce the PUFA already in your body

Body fat turns over slowly. Ray Peat wrote that it takes years to clear stored unsaturated fat after the diet changes. This is what I do while that happens:

1. High carb, low fat. When carbohydrate is the main fuel, less fat is released from storage at once.
2. Coconut oil as the main added fat.
3. Vitamin E. It protects unsaturated fats from oxidation. I use a mixed-tocopherol product with no seed oil carrier.
4. Do not fast or crash diet. Fast fat loss floods the blood with the stored PUFA.
5. Aspirin, which I use with care. Read the risks first.

E-Complete Oral Supplementskin.foodView product

Why the form of vitamin E matters is in the vitamin E guide.

Quick answers

What foods are PUFA?

Seed oils such as soybean, corn, sunflower, safflower, cottonseed, grapeseed and canola oil, the foods made with them (mayonnaise, dressings, chips, fried and baked goods), nuts and seeds, chicken skin, pork fat, fatty fish and fish oil.

What PUFA foods should you avoid?

Start with seed oils and anything fried or packaged that lists vegetable oil. Then cut back on nuts, seeds, nut butters, margarine and fish oil supplements.

Is PUFA good for health?

It is disputed. Cohort studies link higher linoleic acid intake to less heart disease, and guidelines recommend it. Recovered data from two older randomized trials found no benefit or more deaths when saturated fat was replaced with linoleic acid.

How do you avoid PUFA?

Cook at home with butter, coconut oil or tallow, read labels for vegetable oil, avoid deep-fried restaurant food, and replace nuts and packaged snacks with fruit, dairy and potatoes.

How do you reduce PUFA in your body?

Stop eating it and give it time, because body fat turns over slowly. A higher-carbohydrate, lower-fat diet, coconut oil and vitamin E are the steps described in this article.

Which oils are low in PUFA?

Coconut oil has about 2% linoleic acid, butter and beef tallow about 2 to 3%, and olive oil about 10%.