Rice is the most widely consumed staple food for a large part of the world's human population. It can serve as a good source of B vitamins, including iron, riboflavin, niacin, and thiamin. It is also an excellent source of magnesium and manganese. Recently, a team of researchers from the American Chemical Society successfully engineered transgenic rice that contains blood pressure-lowering peptides.
This type of rice, though, is not yet something that the public can purchase and the study only involved hypertensive rats and not humans. Nevertheless, the result paves the way for a future where foods are genetically modified to address certain health issues.
The hypotensive activity of transgenic rice
Hypertension or high blood pressure (HBP) is a condition in which the blood pressure or the force of the blood pushing against the walls of the blood vessels is consistently too high. Over time, the friction and force of the HBP can damage the delicate tissues inside the arteries, which is the reason why the condition is a major risk factor for stroke and cardiovascular disease. To treat HBP, a common class of synthetic drugs called angiotensin-converting enzyme (ACE) inhibitors is used. This drug class is known to dilate or widen the blood vessels, increase the amount of blood the heart pumps, and lower blood pressure, according to the American Chemical Society.
ACE inhibitors, though, likely have some side effects, including dry cough, kidney impairment, skin rashes, and headache. On the other hand, natural ACE inhibitors from foods such as meats, plants, fish, milk, and eggs may have fewer side effects. The challenge, however, is that it is time-consuming and expensive to purify large amounts of these natural ACE inhibitory peptides from foods.
In their study, which appeared in the Journal of Agricultural and Food Chemistry, authors Dandan Qian from the Key Laboratory of Plant Molecular Physiology in China and colleagues aim to genetically modify rice since it is one of the most commonly consumed foods. Their purpose is to produce a mix of ACE inhibitory peptides from other sources of food.
Genetically modifying rice
The team introduced a gene to rice that consisted of blood-vessel-relaxing peptide and nine connected ACE inhibitory peptides. They then confirmed that the rice plants contained a high level of the said peptides to extract total protein from the transgenic rice. After this, they administered the rice to hypertensive rats to observe its effect. Only two hours after the treatment, there was a reduction of blood pressure among the hypertensive rats. The group also administered wild-type rice proteins to other groups of hypertensive rats but they did not experience the same result.
Administering flour made from transgenic rice
Administering flour from the transgenic rice to hypertensive rats in a more than 5-week period also reduced their blood pressure. The effect was observed even after a week. Qian and the team said that they did not observe any side effects on the treated rats in terms of blood biochemistry, development, or growth. They believe that if the peptides have the same effects when administered to humans who have high blood pressure, then it would only take a tablespoon of genetically modified rice daily for a 150-pound adult to treat or prevent hypertension.
They also highlighted in their study that they extracted multiple antihypertensive peptides from the transgenic rice seed and administered these intragastrically into hypertensive rats with different dosages. “Our work provides an alternative source of natural antihypertensive agents,” their study reads.
The co-authors of the study include Bin Qiu (Institute of Laboratory Animal Science - China), Nan Zhou (Key Laboratory of Plant Molecular Physiology - China), Fumio Takaiwa (Plant Molecular Farming Unit of the Institute of Agrobiological Sciences - Japan), Weidong Yong (Chinese Academy of Medical Sciences - China), and Le Qing Qu (Innovative Academy of Seed Design - China).
The US Centers for Disease Control and Prevention shares that nearly half or 45% of adults in the US have hypertension defined as a diastolic blood pressure ≥ 80 mm Hg or a systolic blood pressure ≥ 130 mm Hg. Only one in four or 45% of adults with HPB have their condition under control. About 30 million or half of adults with blood pressure ≥140/90 mm Hg are required to take medication to control their blood pressure but they are not taking medication or are not prescribed one.
It affects both men and women. Niger was the country with the highest share (35.81%) of women with raised blood pressure in 2015. Other countries with a high share of adult women aged 18 years and older with raised blood pressure were Somalia (32.16%), Ethiopia (31.72%), Mauritania (31.36%), Mali (33.63%), Chad (33.84%), and Central African Republic (30.81%).
Between 2011 to 2012 alone, the top hypertension drug in the US was Diovan and it generated around US$ 1.96 billion in revenue. It was followed by Diovan hydrochlorothiazide ($1.63 billion), Metoprolol succinate ($9.82 million), Benicar ($7.02 million), and Benicar hydrochlorothiazide ($5.99 million), according to database company Statista. This goes to show how much can be saved if the public focuses on increasing the nutritional value of crops or foods rather than spending on hypertension drugs.
Transgenic rice that gives high yield despite water scarcity
In 2017, a group of Indian, Canadian, and Chinese scientists also developed transgenic rice that gives high yields despite severe water scarcity.
The team developed the rice variety by transferring a gene from the flowering plant Arabidopsis thaliana into the Indian rice samba mahsuri. The gene they introduced to the rice plant is involved in pathways controlling development and growth. Although it has no agronomic value, Arabidopsis thaliana has been widely used for research purposes. The results of their study, which appeared in the journal Scientific Reports, highlight that the transgenic rice performed better compared to their unmodified counterparts under water-scarce conditions. The Arabidopsis thaliana gene increased the rice’s length of panicle that covers the grain, height, water use efficiency, chlorophyll content, and photosynthesis efficiency.
The potential benefits of transgenic rice now go beyond solving the major constraints in rice production, which needs extensive irrigation. Qian and the team show how it can also help people with high blood pressure.