Benefits of natural dietarytransfatty acids towards inflammation, obesity and type 2 diabetes: defining the n-7transfatty acid family

Abstract

Natural trans fatty acids are trans fatty acids that naturally occur in ruminant-derived foods: milk (derived from cow, ewe, goat), dairy products (yoghurt, cheese) and ruminant meat (beef, lamb). Because natural trans fatty acids are part of the trans fatty acid family, they have been compared for decades to their industrial counterparts on a cardiovascular outcome’s basis. At current dietary intakes, it is now well recognized that natural trans fatty acids are neutral towards cardiovascular health. Still, the negative connotation remains. It is usually taken for granted in the scientific community that natural trans fatty acids have no known physiological function and therefore no particular nutritional interest. This prevailing view has totally hidden several studies, which pointed out unsuspected benefits of natural trans fatty acids on inflammation, type 2 diabetes and obesity. Some supplementation studies dealt with pure trans-vaccenic acid (trans-C18:1 n-7) and pure rumenic acid (cis-9, trans-11 C18:2), but remained somewhat aside as they were carried out on rodents. However, recent epidemiological data reached considerable impact, highlighting a protective effect of trans-palmitoleic acid (trans-C16:1 n-7) towards the risk of type 2 diabetes. Bearing in mind that natural trans fatty acids do not just consist of rumenic acid, this review is the opportunity to sum up scientific knowledge about each of these three fatty acids. We shall therefore, review their occurrence in foods, and their physiological impacts. An overlooked aspect of natural trans fatty acids is that they are metabolically connected. The second aim of this review is to underline these metabolic connections. In fact, combining physiological impacts and metabolic pathways unravel shared mechanisms of action of trans-palmitoleic, trans-vaccenic and rumenic acids, that might be explained by their common n-7 trans double bond.

Fatty Acid Composition of Milk from Mothers with Normal Weight, Obesity, or Gestational Diabetes

“…Natural trans fatty acids (TFA) typically result from bacterial activity during rumen biohydrogenation of edible LA and ALA and are therefore found in ruminant-derived foods (milk and meat). Guillocheau et al recently reviewed the body of scientific knowledge on natural TFAs such as trans-palmitoleic (trans-C16:1 n-7) and trans-vaccenic (trans-C18:1 n-7) acids and highlighted that they have similar biochemical characteristics (i.e., n-7 double bond) and physiological effects [ 33 ].…”

Effect of Dietary Vegetable Sources Rich in Unsaturated Fatty Acids on Milk Production, Composition, and Cheese Fatty Acid Profile in Sheep: A Meta-Analysis

“…Our data also showed that some trans FA such as C18:1 t-11, C18:2 c-9, t-11, and C18:3 n-3 increase in sheep cheeses when sheep are supplemented with vegetable UFA. In humans, these natural trans FA have been related to positive effects on inflammation, obesity, and type 2 diabetes (49). More specifically, clinical trials demonstrated that naturally conjugated linoleic acid (CLA; C18:2 c-9, t-11) and C18:3 n-3-enriched cheeses are able to ameliorate the plasma lipid profile, and to reduce endocannabinoid biosynthesis (50), to reduce plasma inflammatory markers, such as IL-6, IL-8, and TNF-a (51).…”

Potential favourable health effects of some dietary uncommon fatty acids

“…Numerous studies show that the risks of cardiovascular diseases with dietary trans fatty acids are attributable to industrial trans fatty acid (Oteng and Kersten, 2020). In contrast, no increase in cardiovascular risk has been observed with the consumption of naturally occurring trans fatty acids at the current consumption levels (Guillocheau et al, 2019). Studies on cells, rodents and humans suggest physiological benefits on inflammation, type 2 diabetes and obesity (Guillocheau et al, 2019), without knowing whether these naturally occurring trans fatty acids act directly or through their metabolites (Guillocheau et al, 2019).…”

“…In contrast, no increase in cardiovascular risk has been observed with the consumption of naturally occurring trans fatty acids at the current consumption levels (Guillocheau et al, 2019). Studies on cells, rodents and humans suggest physiological benefits on inflammation, type 2 diabetes and obesity (Guillocheau et al, 2019), without knowing whether these naturally occurring trans fatty acids act directly or through their metabolites (Guillocheau et al, 2019). Guillocheau et al recently published a comprehensive review on natural trans fatty acids (Guillocheau et al, 2019).…”