But a new study finds people with diets high in trans fats are also more likely to experience the kind of brain shrinkage associated with Alzheimer’s disease!
Trans fat is the common name for a type of unsaturated fat with trans-isomer fatty acid. Unsaturated fat is a fat molecule containing one or more double bonds between the carbon atoms. Since the carbons are double-bonded to each other, there are fewer bonds connected to hydrogen, so there are fewer hydrogen atoms, hence the name, “unsaturated”.
Trans fats are rare in living nature: they are found naturally, in small amounts, in dairy products, beef and lamb. By far the largest amount of trans fat consumed today is created by the processed food industry as a side effect of partially hydrogenating (introducing hydrogen) unsaturated plant fats (generally vegetable oils). These partially hydrogenated fats have displaced natural solid fats and liquid oils in many areas, the most notable ones being in the fast food, snack food, fried food, and baked goods industries. They can only be made by cooking with a very high heat, at temperatures impossible in a household kitchen.
Partially hydrogenated oils have been used in food for many reasons. Partial hydrogenation increases product shelf life and decreases refrigeration requirements. Many baked foods require semi-solid fats to suspend solids at room temperature; partially hydrogenated oils have the right consistency to replace animal fats such as butter and lard at lower cost. They are also an inexpensive alternative to other semi-solid oils such as palm oil.
The consumption of trans fats increases the risk of coronary heart diseaseby raising levels of LDL cholesterol and lowering levels of “good” HDL cholesterol.In 1994, it was estimated that trans fats caused 20,000 deaths annually in the US from heart disease. Health authorities worldwide recommend that consumption of trans fat be reduced to trace amounts.
Now we have another reason to avoid trans fats.
Sharon Kirkey reports for Post Media News, December 29, 2011, that researchers have found that eating too much fast food — and therefore trans fats — is associated with brain shrinkage, similar to the brain shrinkage found in people with Alzheimer’s disease.
In 1989, the Oregon Brain Aging Study was launched, involving 104 people aged 65 and older. All were generally healthy elders, with few smokers or people with diabetes or high blood cholesterol.
Only a handful of studies have looked at the relationship between trans fats and brain function. The purpose of the Oregon research was “to study the effects of age on dementia risk in people that don’t have factors known to increase their risk at the time,” according to lead investigator Dr. Gene Bowman, a naturopathic doctor in the department of neurology at the Oregon Health and Science University in Portland.
Researchers checked the participants’ blood samples for markers of 30 different nutrients. Participants also did a raft of neuropsychological tests, and 42 had MRI scans of their brains as well. The team was interested in three things: cognitive function, total brain volume and white matter changes thought to be a sign of small vessel disease of the brain. (Small vessel disease, also known as cerebral small vessel disease, is an accumulation of plaque deposits in the small blood vessels throughout the brain. It can lead to stroke.)
Among the study’s key findings:
- People who had high levels of circulating trans fats had less brain volume. They also had poorer memory, attention, language and processing speed skills;
- People who had low levels of B vitamins, the antioxidants C and E, and vitamin D had less total brain tissue. Those who high levels of vitamins B-C-E-D had greater total brain volume and better global cognitive function.
- People with higher levels of omega three fatty acids had better executive function — the ability to plan, problem solve, multi-task and perform other functions – as well as fewer white matter lesions on their brain scans.
The findings held after researchers took age, sex, education, hypertension and genetic and other factors into account.
Dr. Bowman said that the evidence suggests that trans fats can replace good fats in cell membranes, “and when that occurs it changes the structure and chemical properties of the cell in an unfavorable way. Trans fats are known to be bad for cardiovascular health. It makes sense that they’re probably bad for the brain, too.”
Bowman recommends avoiding processed foods that list “partially hydrogenated oils” on the ingredient list. “That’s trans fat.”