This is because of the nitrites that are often used as preservatives for bacon, sausage, ham, and other type of processed meat. The salts of nitrite (but also nitrate) are commonly needed to enhance the colour, extend the shelf life of processed meats and also help hinder the growth of harmful microorganisms (such as in Clostridium botulinum). By the way, nitrates, when added to food, convert to nitrites before exerting a preservative function.
There are not that many studies on nitrites triggering headaches. Starting in 1972, a study discovered a number of people, whose headaches were triggered by nitrites. Since then this type of headaches became known as the “hotdog headache”.
Another study found that 5% of people with migraine were more likely to have an attack after eating products with nitrites.
What about nitrate rich vegetables? Can they cause migraine attacks?
As you might know, our healthy vegetables, especially green leafy ones, are actually much higher in nitrates compared to nitrates as food additives. To give you an example, a 100 gr serving of fresh spinach has anywhere from 24 to 387 mg of nitrate, depending on growing conditions. On the other hand, a single 100 g serving of cured ham has as much as 890 mcg of nitrates.
So how come that vegetables are recommented to eat while processed meats are better to avoid? It all comes to the form of nitrates in vegetables and meats. Studies suggest that eating foods rich in natural nitrates from vegetables can help reduce your risk of a number of chronic health conditions, whereas eating foods high in added inorganic nitrates can cause health problems.
Besides, the nitrate-rich vegetables can even help fight migraines! This is because the green leafy vegetables, but also root vegetables and mushrooms contain lots of nutrients like vitamins B, vitamin C, manganese and potassium that help ease migraine attacks and, believe it or not, prevent them.
How do nitrates/nitrites exactly work in your body to potentially cause a migraine attack?
After eating products with nitrates or nitrites, these 2 components are broken down into nitric oxide (NO) via bacteria in the mouth. NO influences the inner layer of blood vessels by widening them. On one hand, this helps lower blood pressure and enhance physical performance, especially during high intensity endurance exercise. On the other hand, an increased production of NO creates the so called ‘nitric oxide stress’, which can trigger migraines in sensitive people. Nitric oxide stress occurs when there is an imbalance in the body’s ability to neutralize free radicals from the production of nitric oxide. In case of eating nitrate-rich vegetables, coping with nitric oxide stress by the body is very effective due to the antioxidant properties of the vegetables that are able to fight free radicals.
Is food the only source of increased production of NO?
The processed meat and vegetables are not the only source of NO formation in our body. NO is also produced by our body by an enzyme (nitric oxide synthase) that converts the amino acid L-arginine into nitric oxide. Especially the significant amounts of NO are made during a slowly spreading wave of altered brain activity that involves dramatic changes in the functions of our neurons, glial cells and our blood vessels (known as cortical spreading depression). NO may be involved in pain signals within the central trigeminal pathway.