Swapping lard for fish oil benefits brain as well as body

By Will Chu

- Last updated on GMT

Few studies have looked at the neurological effects fish oils have on dictating eating patterns and managing weight. ©iStock/Kuo Chun Hung
Few studies have looked at the neurological effects fish oils have on dictating eating patterns and managing weight. ©iStock/Kuo Chun Hung

Related tags Fish oil Obesity Nutrition Fat

In a study that compares the effect different fats have on the brain, unsaturated types such as fish oil were found have beneficial effects on brain inflammation and function.

Writing in the journal Frontiers in Cellular Neuroscience, ​the scientists identified fish oil’s regulation of a brain region that controls metabolic function including the amount of food eaten.

Further results indicated that a diet of fish-oil resulted in no modifications to inflammatory enzyme activity and oxidative stress.

Body weight gain, fat profiles and hormones controlling hunger were also reduced when compared to subjects fed on a high-fat saturated diet containing lard.

The findings, uncovered by researchers from the University of Naples Federico II, detailed the effect nutritional substitution of saturated for unsaturated fatty acids has not only on the body but also the hypothalamic region of the brain.

Fat type affects brain function?

Fish oil Omega-3_iStock_free
Fish oils have shown much efficacy in neuroregulation and function. ©iStock

The effects of a high-fat diet on body mass index (BMI) have been well-documented. What isn’t so clear is the neurological effects fish oils have on dictating eating patterns and managing weight.

A number of overnutrition-related diseases appear to be linked to the malfunctioning of hypothalamic neurons that are vulnerable to nutritional oxidative stress and inflammation​.

It has been shown that overnutrition can activate​ a ‘master switch’ in the hypothalamus, which is the area sensing nutrition status and regulating metabolism.

Co-authors of the study, professor Marianna Crispino and professor Maria Pina Mollica, began by feeding rats either a control diet (CD), a high-fat diet (HFD) containing either fish oil (FD; rich in ω3-PUFA) or lard for six weeks.

Throughout the experiment, body weight and food intakes were monitored daily to calculate weight gain and gross energy intakes.

The activation of AMPK, a pro-inflammatory enzyme, IKKβ, TNF-α, a marker for inflammatory state and oxidative stress were also analysed in the hypothalamus. Serum lipid profiles and pro-inflammatory restrictions were also recorded.

"We were amazed to establish the impact of a fatty diet onto the brain,” ​said Crispino.

“Our results suggest that being more aware about the type of fat consumed with the diet may reduce the risk of obesity and prevent several metabolic diseases.”

The study criteria have been repeated on a number of occasions​, where FD subjects exhibited large decreases in body fat mass compared to LD group.

Increases in body weight were not associated with an increase in food intake, but with an increase in energy intake.

Fat interference

rat experiment animal research science obesity fat weight iStock.com Argument
The study involved feeding rats a diet high in lard or fish-oil. ©iStock/FikMik

Considering how this increase in energy intake affected the hypothalamus, the team said that while the expression of AMPK was not modified by diet, levels of the active phosphorylated form of the enzyme (pAMPK) were significant in the LD group.

“The administration of this diet leads to the activation, at hypothalamic level, of a key enzyme regulating the food intake,”​ the study theorised.

“This effect was observed exclusively with LD diet suggesting that the type of fats affects pAMPK expression.”

The team also commented on the effect of a diet rich in saturated fat (lard), observing its detrimental effects on the hormones insulin, leptin and adiponectin.

Leptin and insulin are present in the hypothalamic neurons that are involved in body weight regulation, and the loss of leptin and insulin in the hypothalamus can promote​ obesity and type 2 diabetes.

Commenting independently on the research, Dr Harry Rice, VP of regulatory & scientific affairs for the Global Organisation for EPA and DHA Omega-3s (GOED), said that understanding food intake regulation could help reverse the global obesity epidemic, but food intake was as much about sociology as it is about physiology.

"It's important to understand the limitations of any potential intervention," ​he commented. "While it's clear that the fish oil diet was superior to the lard diet under the current experimental conditions, more research is needed to better understand the mechanisms of interest. At the same time, there is more than enough positive research to recommend an increase in omega-3 (EPA and DHA) fish oil intake for cardiovascular health." 

Source: Frontiers in Cellular Neuroscience

Published online ahead of print, http://dx.doi.org/10.3389/fncel.2016.00150

“Effects of an High-Fat Diet Enriched in Lard or in Fish Oil on the Hypothalamic Amp-Activated Protein Kinase and Inflammatory Mediators.”

Authors: Marianna Crispino et al.

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1 comment

Good Lard, Bad Lard: What Do You Get When You Cross a Pig and a Coconut?

Posted by Steven Weil,

Studies like these (using standardized 'lab chow diets'), have to be interpreted cautiously. The high fat diet group (HFD rich in lard (40% fat) may not be what its thought to be, in fatty acid content. Typically commercial Lard is 41% SFA, 47% MUFA, and 12% PUFA, of which .1% is omega 3 in the form of ALA.
Lab chow diets may be very different. Lard-based, high-fat rodent diet, “D12492”, has been found to have a significant discrepancy between the actual fatty acid profile as determined by direct analysis of the lard and the previously reported fatty acid profile, which had been estimated using the USDA database.

The actual fatty acid profile is much higher in PUFAs, at the expense of both saturated and monounsaturated fats. In fact, the company had originally estimated the diet to provide 17 percent of its fat as PUFA, but now estimates it to provide a whopping 32 percent! The particular fatty acids that are decreased the most are palmitic, stearic, palmitoleic, and oleic acids. These are the primary fatty acids that pigs, humans, and other animals produce when we make fat from carbohydrate. The ratio of omega-6 linoleic acid to omega-3 linolenic acid is almost Double what had been estimated based on the USDA database, suggesting that the oils the pigs are consuming are particularly rich in omega-6 fatty acids.

Good Lard, Bad Lard: What Do You Get When You Cross a Pig and a Coconut?

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