Synthetic Trans Fats made their first appearance in 1907, when German chemist Edwin Kaiser contacted a soap manufacturer Proctor and Gamble, about a new chemical process that could create a solid fat from a liquid. Proctor and Gamble were interested in producing a solid form of cottonseed oil, as they had recently formed a company that was processing this waste product of cotton farming, and creating cotton seed oil, they saw this as cheap alternative for soap production. Soon the company’s scientists produced a new creamy, pearly white substance out of cottonseed oil. It looked a lot like the most popular cooking fat of the day: lard. Before long Procter & Gamble sold this new substance (known today as hydrogenated vegetable oil) to home cooks as a replacement for animal fats .
In 1910 Proctor and Gamble implemented an enormously successful marketing campaign. Crisco was born and cooks across the world were effectively convinced that this new factory created fat was a far superior option than butter or lard. Health claims on food packaging were then unregulated, and the copywriters claimed that cottonseed oil was healthier than animal fats for digestion . Procter & Gamble’s claimed that Crisco would “Touch the lives of every American”, sadly their prediction proved correct in a manner that they never could have anticipated. The substance was 50 percent trans-fat, and it wasn’t until the 1990s that its health risks were understood .
Whilst trans-fat can be found naturally occurring in some milk and meats, the primary dietary source for trans-fat is from the partially hydrogenated oils found in most processed foods.
Consequently it is interesting to consider the possible implications of consuming naturally occurring trans-fats in comparison to industrially produced trans fats.
In June of this year Hansen CP et.al., wanted to consider the fact that studies have suggested the total intake of trans-fatty acids is positively associated with changes in body weight and waist circumference, whereas intake of trans fatty acids from ruminant dairy and meat products has not been associated with weight gain. Their findings concluded that naturally occurring trans-fat intake was not significantly associated with subsequent changes in body size, shape or composition and the 95 % confidence intervals indicate that any relevant associations are unlikely to have produced these observations.
Industrially produced trans-fat however paints a very different picture. Following are studies that implicate these fats in cognitive dysfunction, mental health disorders, coronary heart disease, diabetes, foetal growth rates, and cancer.
A study publish on the 17th of June this year titled ‘Fats to Forget’ focuses on the impacts of trans fats on memory. They concluded that dietary trans fatty acid consumption is linked to worse memory in adults during years of high productivity, adults age <45. 
In 2012 a study was done to determine whether dietary trans fatty acids are associated with aggression/irritability. This study provided the first evidence linking dietary trans fatty acids with behavioural irritability and aggression. 
Oh, K et.al, examined the associations of dietary fat and specific types of fat with risk of coronary heart disease (CHD) among 78,778 US women initially free of cardiovascular disease and diabetes in 1980. The associations between intakes of polyunsaturated fat and trans-fat with CHD risk were most evident among women younger than age 65 years. Trans-fat intake was associated with increased risk of CHD, particularly for younger women.  In a related study they found a link to diabetes where trans-fat may have influenced the risk of CHD mainly by its adverse effects on blood lipid levels, which could be more clearly seen among women with less insulin resistance. 
Increase foetal growth rates have also been linked to the ingestion of industrially produced trans-fat. 
In considering the link between cancer and trans-fat a study titled ‘Intake of trans fatty acids from partially hydrogenated vegetable and fish oils and ruminant fat in relation to cancer risk’ produced the following conclusion. Trans fatty acids from different sources showed different associations with cancer risk. More unfavourable risks were found for partially hydrogenated fish oils (PHFO-TFA) and ruminant fat ( rTFA) intake than for partially hydrogenated vegetable oils (PHVO-TFA) intake. For PHFO-TFA, we observed significant positive trends for stomach cancer and multiple myeloma, with significantly increased risk of multiple myeloma in the highest compared to lowest intake category. Furthermore, we found significantly increased risk of rectal cancer in the highest compared to lowest intake category. Significant inverse trends were observed for prostate cancer and lung cancer in women. However, for lung cancer, we found a significant positive association in men and a no significant positive association in women when restricting the analysis to never-smokers. For PHVO-TFA, we observed significant inverse trends for all cancers, pancreatic cancer in men, CMM in men, nonmelanoma skin cancer, cancer of the CNS in women and NHL, with significantly decreased risks in the highest compared to the lowest intake category for pancreatic cancer and NHL. For rTFA, we found significant positive trends with increased risks in the highest compared to the lowest intake category for all cancers, cancer of the mouth and pharynx, nonmelanoma skin cancer and NHL. Furthermore, we found a significant positive trend for postmenopausal breast cancer. Significant inverse trends were found for multiple myeloma and for CMM in women, with significantly decreased risk in the highest compared to the lowest intake category for multiple myeloma. 
On the 16th of July 2015 the FDA announced that food manufacturers must remove partially hydrogenated oils, the main source of artificial trans-fat, from processed foods in the next 3 years. It has been stated by the FDA that ‘the elimination of partially hydrogenated oils could prevent 20,000 heart attacks and 7000 deaths from heart disease each year”.
I believe the next question should be: what will replace trans-fats? Hopefully we will see a return to the use of butter and lard rather than another industrially produced substitute.
Despite that strong evidence supporting the adverse affects of industrial trans fatty acids on our health for the past decade, it has taken until now for the FDA to step up and take action to reduce the intake in American diets, I only hope that Australia follows their lead on this one. Unfortunately the implementation of this decision will not be seen for some years yet.
 http://www.theatlantic.com/health/archive/2012/04/how-vegetable-oils-replaced-animal-fats-in-the-american-diet/256155/  http://www.medscape.com/viewarticle/839061_3  http://www.medscape.com/viewarticle/846567  http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0128129#sec012  http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0032175#s4  http://www.ncbi.nlm.nih.gov/pubmed/15781956  http://www.ncbi.nlm.nih.gov/pubmed/26074002  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3192475/  http://aje.oxfordjournals.org/content/161/7/672.long  http://onlinelibrary.wiley.com/doi/10.1002/ijc.27737/full