Many people are not aware that you should never cook at high temperatures. Grilling, frying, or sauteeing at high temperatures puts you at risk for several health problems ranging from heart disease, inflammation, and cancer.
Why High Temperature Cooking is Bad
Researchers at Mt. Sinai School of Medicine in New York concluded earlier this year that frying, sautéing, or grilling food at high temperatures could lead to an increase in inflammation-producing agents in the body called AGEs.
These compounds, also known as glycotoxins, are an important part of the metabolic process and aren’t innately dangerous — but, as with many things, too much of them can be harmful.
A higher concentration of AGEs in the blood can increase inflammation — something that would be detrimental to patients with rheumatoid arthritis (RA) and other inflammatory diseases.
AGEs are not just released with high cooking temperatures, but they are also naturally found in raw animal products such as meat.
The problem is that cooking certain foods at high temperatures can actually form new AGEs.
When added to foods where AGEs are already present, this can create a problematic quantity in the blood.
“It’s easy to remember,” says Jennifer White, a certified nutritional health coach and arthritis patient. “We associate inflammation with flames, or being hot. So to dial down the inflammation, dial down the heat when cooking meat.”
Undercooking meat, poultry, eggs, and fish can also be problematic, so the key is to simply practice balance, mindful eating, and reduced exposure to AGEs.
Incorporating raw vegetables and fruits into a balanced diet may help reduce exposure to dietary AGEs and additional inflammation-causing AGEs due to cooking other types of food at hot temperatures.
The research indicates that potentially restricting the amount of dietary AGEs could improve health in many ways, not just in regard to reducing inflammation.
Scientists have long bee aware of higher rates of heart disease among South Asian people, and new research suggests that high-temperature cooking (such as deep frying) could partly be to blame.
The research specifically looked at people from India, Pakistan, Bangladesh and Sri Lanka, where deep frying is more common, compared to China, where it is less common and they are less susceptible to coronary heart disease (CHD).
Cooking food at high temperatures changes its chemical structure, producing toxic products called NFCs, such as trans-fatty acids (TFAs) and advanced glycation end-products (AGEs).
These are linked to damaging processes in the blood vessels, which may lead to high blood pressure and hardening of the arteries, researchers suggested.
Since South Asian food is diverse, they focused on Indian cuisine, and broke this down into North and South India. Roasting and frying are the main cooking methods in both regions. Although Chinese cuisine includes frying, the food is mainly cooked by braising, steaming, and boiling, which produce less NFCs because of the lower cooking temperatures and lower fat content.
The researchers suggest that cooking food at high temperatures could increase the risk of heart disease by creating toxic products called NFCs, which early studies show could increase heart disease risk. But more studies need to be done to confirm this.
“South Asian people often have a high saturated fat intake and trans fat intake, partly due to their use of ghee (clarified butter – a saturated fat) and vanaspati ghee (a type of hydrogenated vegetable oil, which is high in trans fats), which both increase cholesterol levels. To reduce the risk of developing heart disease, use healthier unsaturated oils and cut down on fried food.”
The researchers have made clear that the research showed a link rather than a cause and effect, and that more research is needed.
“It makes sense to avoid snacks that are cooked in high-temperature oils,” said Bhopal, who himself has now switched to cooking olive oil. “Olive oil does not heat up to a very high temperature,” he said.
one of the major cooking rules was to cook food on a low flame. While it takes longer to cook foods this way, new science is confirming the reasoning.
Cooking over a low flame ensures that the food is never overheated, thus sparing the nutrients while making the food more easily digested and assimilated.
the FDA put out a report warning against overcooking your food, as it creates a chemical called, acrylamide, which has caused cancer in animal studies. In 2010, the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives (JECFA) concluded that acrylamide is also a human health concern: (1)
“High temperature cooking, such as frying, roasting, or baking, is most likely to cause acrylamide formation…acrylamide is found mainly in foods made from plants, such as potato products, grain products, or coffee. Acrylamide does not form, or forms at lower levels, in dairy, meat, and fish products. Generally, acrylamide is more likely to accumulate when cooking is done for longer periods or at higher temperatures.”
Acrylamide is formed when the sugar or starches in the plant stick to an amino acid called asparagine, which naturally occurs in the plant. These are all perfectly healthy until you overheat them!
In one study, French fries produced acrylamides when the cooking temperature reached 300-375 degrees Fahrenheit. Toasted bread was also studied, and it was found that lighter browned toast had significantly less acrylamides than darker toasted bread. (3)
Sadly, researchers believe that 40% of the calories that make up the American diet contain acrylamide.
We all know what happens when you overcook foods with a lot of sugar: the sugar caramelizes. This is an example of the sugar reaching a temperature where it can glycate and attach to asparagine.
The best way to avoid this chemical toxin is to do the following:
- Boil or steam your veggies.
- Bake with low sugar-content ingredients and veggies.
- Don’t over-toast or over-fry your foods; it’s best to avoid frying anything.
- Cut your veggies into smaller pieces so they do not require as much heat to cook.
- Choose tea over coffee, as it has negligible amounts of acrylamide.
A Word on Coffee
Unfortunately, coffee has extremely high levels of acrylamide, so it’s best to limit your intake. Avoid pre-ground or instant coffee, as it has significantly more acrylamide than fresh brewed coffee. (2)
The National Cancer Institute at the National Institutes of Health reported on the cancer risks from cooking meat at high temperatures. (1) When meat from the muscle of beef, pork, fish and poultry are cooked using high temperatures, cancer-causing heterocyclic amines (HCAs) and polycyclic hydrocarbons (PAHs) are formed. HCAs and PAHs have been found to be mutagenic – that is, they cause changes in DNA that may increase the risk of cancer. (1)
The report suggests that the cooking time, the heat used, the type of meat and method of cooking will determine the amount of HCAs and PAHs formed. Meats cooked at high temperatures, especially above 300 degrees Fahrenheit (as in grilling or pan frying), or that are cooked for a long time (well-done) tend to form more HCAs. For example, well-done, grilled, or barbecued chicken and steak all have high concentrations of HCAs. (1)
The National Cancer Institute report suggested that high levels of HCAs and PAHs can cause cancer in animals, but made the point that the effect in humans was unclear. Since the 2010 National Cancer Institute study, more recent 2012 studies have confirmed the link between a diet of meats cooked at high temperatures and cancer in humans. (2,3)
HCAs are formed when amino acids – the building blocks of proteins, and sugars, and creatine – a substance found in muscle, react at high temperatures. A similar process also takes place in plant-based foods creating dangerous acrylamides. PAHs are formed when fat and juices from meat grilled directly over an open fire drip onto the fire, causing flames. These flames contain PAHs that then adhere to the surface of the meat. PAHs can also be formed during other food preparation processes, such as the smoking of meats. (1) PAHs are also found in charred foods, as well as in cigarette smoke and deadly car exhaust fumes. (1)
The National Institutes of Health suggest the following to avoid dangerous levels of HCAs and PAHs: (1)
- HCA and PAH formation can be reduced by avoiding direct exposure of meat to an open flame or a hot metal surface.
- Reduce the cooking time to avoid eating well-done meat.
- Turning meat over while on a high heat source can substantially reduce HCA formation.
- Remove charred portions of meat and refrain from using gravy made from meat drippings.
According to Ayurveda, we should cook all foods over a low flame and never eat burned or charred foods. Boiling meats in a stew is a traditional method that minimizes the high temperature risks of burning or overheating the food.