The bottle your feed wants you to throw out

Fifteen randomised trials fed people extra omega-6, then measured their inflammation.

Sunflower, canola, soybean and rapeseed oil are this week’s named cause of stiff mornings. The claim runs like this: the omega-6 in them, linoleic acid, converts into arachidonic acid, and arachidonic acid is the raw material for inflammatory chemicals. Every step in that chain exists.

⚡ 10-Second Pulse

What is in your pan this week?

🚫 Cut them already 😕 Cutting back 🍳 Still using them

The conversion step is throttled hard. About 0.2% of the linoleic acid you eat becomes arachidonic acid. A review of 36 trials in adults on Western diets found that raising linoleic acid intake left the arachidonic acid in their tissues unchanged. More omega-6 on the plate did not put more of it in the body.

Guy Johnson and Kevin Fritsche pooled 15 randomised trials in 2012 in which people were fed extra linoleic acid and had their blood measured: C-reactive protein, fibrinogen, TNF-alpha, cytokines, adhesion molecules. Not one of those markers rose significantly. A larger pooling in 2017, 30 trials and 1,377 participants, landed in the same place.

0.2%

converts to arachidonic acid

trials, no marker rose

1,377

people in the 2017 pooling

The mechanism holds up in a textbook and does not show up in a blood test. My verdict: clearing your kitchen is not the joint move it is being sold as.

What those trials did not measure. They tracked blood markers in healthy adults, not knee scores in people with arthritis, and nobody has run the study that would settle it: swap your oil for six months, rate the joints at the end. The 2012 review also carried a funding note: an industry grant, with its lead author having consulted for two oil companies. So the finding is an absence of evidence for the claim, not a case for frying everything.

✅ Tonight’s Fix

Add, do not subtract. Goldberg and Katz pooled 17 randomised trials of omega-3 supplements in inflammatory joint pain. After three to four months, patient-rated pain, minutes of morning stiffness, the count of painful joints and anti-inflammatory drug use were all lower than placebo. The effects were modest and most of the trials ran in rheumatoid arthritis rather than wear-and-tear arthritis. Put two oily fish meals on this week’s shopping list before you close this email: sardines, mackerel, salmon or herring.

On my list → Join today’s streak

More On Your Plate

●	Stop reusing frying oil. Oil that is heated, topped up and heated again over weeks builds up oxidation products, and that is a separate question from the fresh bottle. Pour the pan off after tonight’s cooking instead of saving it in a jar.
●	Turn the “olive oil” bottle around. Plenty of supermarket bottles are a blend, mostly sunflower with a little olive, and the ingredient order on the back gives it away. Next shop, buy one with a single oil named on the label.
●	Shift the ratio from the other end. Most people eat 10 to 20 times more omega-6 than omega-3. A tin of sardines on toast is a smaller change to make than emptying your kitchen, and it closes the gap from the omega-3 side. Buy four tins this week.

Quick Vote

Where do you think your stiff mornings come from?

🍴 What I eat

🚶 How I move

From the Mailbag

“I threw out every seed oil in the house a month ago and my knees are exactly the same. What did I do wrong?”

Alan, 61

Nothing, Alan. Taking linoleic acid out has not been shown to lower inflammatory markers in the trials that tested it, so a month without sunflower oil was never likely to move your knees. The diet changes with joint trials behind them are the additive ones, oily fish or an omega-3 supplement run for three to four months. Cook with whichever oil you prefer the taste of, and spend the effort on what goes in rather than what comes out.

Got an ache question? I read every one.

Ask me anything →

Keep moving,

The Ache Report

P.S. If you take fish oil capsules, take them with a meal that has fat in it. EPA and DHA absorb several times better alongside a fatty meal than on an empty stomach, so the same capsule with breakfast eggs beats the same capsule with black coffee.

Was today useful? One click tells me everything.

👍 Loved it 😐 It was OK 👎 Not for me

The bottle your feed wants you to throw out

Keep Reading