The health effects of fatty acids and other lipids in the diet has played an important role in shaping nutritional research over the last 50 years. Saturated fat and cholesterol have been portrayed by mainstream ‘authorities’ as demons run amok and that consumption of these deadly substances is the primary cause of heart attacks as well as a contributory factors in obesity. However, much of the populist opinion of saturated fat and cholesterol is based on fantasy and wishful thinking rather than hard scientific observation. In fact it is tempting to conclude that the propaganda model created to demonise these fatty acids was deliberately created to divert attention away from the real cultripts of Western lifestyle diseases. For while we have focused our attention of the innocent saturated fatty acids, the oxidised and processed oils that euphemistically are referred to by the food industry as ‘polyunsaturated’, ‘cooking’, or ‘sunflower’ oils have slipped into our food chain and began to hollow out the health from within us like insidious poisons.
Polyunsaturated oils are susceptible to oxidation, and in fact in vivo oxidation of such oils enzymatically is favourable because these oxidised products activate genes that regulate cellular function. Oxidised oils can activate PPAR-α (peroxisome proliferator-activated receptor alpha), a transcription factor that plays a pivotal role in regulating lipid homeostasis. The target genes for PPAR-α are involved in lipid catabolism, lipoprotein transport and clearance and thermogenesis. This explains the benefits of polyunsaturated oils on weight loss and lipoprotein metabolism. However, oxidising oils chemically by exposing them to heat and light before consumption creates a range of hydroxy and hydroperoxy products that can may interfere with the normal regulation of gene expression. Pan frying, deep frying and processing of polyunsaturated oils is known to create products that may have detrimental health consequences. Such oxidised oils are absorbed from the small intestine, where they may subsequently de a driver of metabolic disease.
It cannot be stressed how bad oxidised oils can be to the health. Regular consumption of oils has been linked to cardiovascular disease and cancer. That consumption of oxidised oils is also associated with consumption of trans fatty acids is problematic also. Many foods containing oxidised oils also contain trans fatty acids and both are known to detrimentally alter metabolic regulation. It is known that during early pregnancy, the growing foetus is particularly susceptible to exposure of poor quality nutrition on the part of the mother. Increasingly, low intakes of micronutrients and high intakes of toxins and metabolic poisons by the mother are being linked to metabolic disease in the offspring during adult life in animal experiments. Research investigating the effects of maternal diet on the risk of obesity in the offspring for example has found that a number of factors may be pivotal in regulating future obesity risk. In some cases such foetal damage may not manifest until adult life, and in particular such disorder may be gender specific.
The effects of oxidised fatty acids on the health of mice born to mother exposed to high concentrations in their diet has been investigated in the nutritional literature1. Pregnant mice were fed either a control diet containing 10 % fresh soybean oil or a treatment diet containing 10 % oxidised soybean oil for their entire gestation period. After birth the pups were nursed by mice fed fresh soybean oil for 3 weeks, weaned onto a standard diet for 4 weeks, and then fed a high fat obesogenic diet for 5 weeks. Sampling of the mice during pregnancy showed that those mice fed the oxidised oil had higher concentrations of activated PPAR-α in their livers compared to the mice fed fresh soybean oil. Although all the pup were treated the same following parturition, when the researchers analysed the pups at the end of the study they found that the female pups born to the oxidised soybean oil mice were at a higher risk of diet induced obesity. However, the male mice were at a reduce risk of diet induced obesity.
Are these results relevant to humans and can we make any solid conclusions based on them? Well, not really, as mice are not humans and diets in humans are not controlled in the same way. While these results are interesting, trying to extrapolate the data to humans would be very unscientific. However, what we can say is that evidence such as this highlights the effects that that maternal diet can play in shaping the obesity rates of future generations. The possibility that the body composition experienced in adulthood may be partially predetermined by the diet that your mother ate while she was pregnant is a real possibility. Other studies support this intrauterine nutrition theory with some evidence coming from human studies (here). That oxidised cooking oil has the ability to regulate gene expression and alter the risk of disease decades into the future is worrying based on the high concentrations of such fatty acids in the Western diet. Until more is understood about the consequences, oxidised fatty acids should be avoided, particularly during pregnancy.