Have your steak and eat it - beef with omega-3 fatty acids reared in China
Can't stand fish but know it's good for you? Chinese-reared cattle have meat engineered to contain high levels of the beneficial acids associated with fish oils
We’re often told to include some oily fish in our diets because they’re rich in omega-3 fatty acids, which can help protect against obesity and cardiovascular and neurodengerative diseases. But what if you just can’t stomach salmon, tuna, sardines – or anything fishy?
Easy. Have beef instead – or at least beef from a type of transgenic cattle recently reared by Chinese scientists to be rich in the beneficial fatty acids associated with fish oils.
Reporting this week in the journal Biotechnology Letters, the team from Northwest A&F University and the National Beef Cattle Improvement Centre, both in Yangling, Shaanxi, explain how they’ve successfully introduced a gene into fetal cells from Luxi Yellow cattle, a Chinese breed with a high beef yield.
"We have provided the first evidence that it is possible to create a new breed of cattle with higher nutritional value in terms of their fatty acid composition," says corresponding author Linsen Zan from the College of Animal Science and Technology at the university.
Alpha-Linolenic acid (ALA), eicosapentaenoic acid (EPA) and docasahexaenoic acid (DHA) are the main omega-3 fatty acids. Linoleic acid (LA) is the primary dietary omega-6 polyunsaturated fatty acid.
ALA is found in some vegetable oils, such as soybean, rapeseed (canola), and flaxseed, and in walnuts. ALA is also found in some green vegetables, such as Brussels sprouts, kale, spinach, and salad greens.
EPA and DHA is found in fatty fish. The body partially converts ALA to EPA and DHA.
In spite of the protective effects of omega-3 fatty acids, also known as long chain n-3 polyunsaturated fatty acids, against human diseases, the researchers note that levels of these fatty acids in the diet have decreased over the years.
At the same time, the levels of shorter chain omega-6 (n-6) polyunsaturated fatty acids, have increased. An increased ratio of n-6/n-3 polyunsaturated fatty acids in the daily diet creased has been linked with the development and progression of cardiovascular diseases, obesity and neurodegenerative diseases.
The transgenic cattle not only showed significantly increased contents of omega-3s in muscle tissue, but also the ratio of n-6/n-3 PUFAs was 0.95:1, which was lower than that 5.33:1 of typical cattle.
Genes similar to those used in this study have previously been introduced to pigs, dairy cattle and sheep by international research groups.
However, the Chinese scientists still need to figure out the best way to rear these transgenic cattle. Of 14 calves that successfully received the gene, 11 died at less than four months old, mainly from inflammation and from an infection common to cattle, haemorrhagic septicaemia.
Further research is needed to determine the causes. Abnormalities may result from the incomplete reprogramming of cells or from some genes being turned on and off during the generation of embryos.
"There is much to learn about the best scientific techniques and the best husbandry required to make beef a rich animal source of omega-3 oils for human nutrition, but we have taken the first step," says lead author Gong Cheng.