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red onion Do Onions help lower blood sugar levels in diabetics?The incidence of diabetes has risen dramatically over the past thirty years. According to the CDC, the incidence of diabetes has risen from 3.3 to 8.2 per 1000 population from 1980 to 2008 in the United States. That represents and increase of over 148%. Part of this increase has been linked to the rising obesity epidemic in what has recently been coined the diabesity epidemic.

Diabetes itself is generally classified as one of three different types. Type 1 diabetes refers to an autoimmune disease in which there is a defect in insulin secretion from the pancreas. It accounts for 5-10% of the cases of diabetes and occurs most often in children and young adults. In contrast, type 2 diabetes is a metabolic disorder characterized by a defect in insulin secretion and/or insulin resistance. The third type is referred to as gestational diabetes which occurs in pregnant women.

Onions have long been known to have several putative health benefits. Onions are rich in flavinoids such as quercetin as well as sulfur compounds. The health benefits of onions have been linked to everything from the common cold due to diabetes and osteoporosis.

Researchers from the department of pharmacology at the University of Gezira published the results of a preliminary study on the antidiabetic properties of red onion (allium cepa) in the journal, Environmental Health Insights [1]. The purpose of their study was to investigate the hypoglycemic properties of red onion in patients with Type 1 and Type 2 diabetes.

The study itself included two groups of 21 patients each comprised of patients with either type 1 diabetes (group 1) or type 2 diabetes (group 2). The patients included in this study were under the age of 50, not taking medicine for other health conditions, and did not smoke or consume alcohol. The participants were given 100 g of red onion either while fasting or following an oral glucose tolerance test.
Type 1 diabetes results:

Fasting blood glucose was lowered by 145 mg/dl in response to administration of insulin (4 hours later). In comparison, 100 g of allium cepa (red onion) resulted in a 89 mg/dl reduction in fasting blood glucose levels (4 hours later).

Next, this group participated in an oral glucose tolerance test (GTT) in which they were administered 75g of dextrose. Insulin administration lowered their blood sugar by 152 mg/dl (4 hours later) while allium cepa resulted in a reduction of their blood sugar by 120 mg/dl. Water alone was also used as a comparison and it resulted in a 77 mg/dl reduction in blood sugar levels fours hours after the dextrose challenge.
Type 2 diabetes results:

For fasting blood glucose levels, 100 g of crude red onion resulted in a 40 mg/dl reduction in blood glucose levels, four hours later. In comparison, administration of 5 mg of the diabetes drug, glibenclamide, resulted in a reduction of 80 mg/dl.

Following the induced hyperglycemia (GTT), 100 g of allium cepa resulted in a 159 mg/dl reduction in blood glucose levels compared to water 55mg/dl and glibenclamide 114 mg/dl.
Study conclusions:

The study authors succinctly concluded the following:

Allium cepa in addition to its nutritional values has hypoglycemic effects that could be beneficial in management of type 1 and type 2 diabetic patients of all age groups, especially the level of its safety as reflected by its worldwide use as vegetable.

Another interesting point made by the study authors was that they observed an increase in blood glucose levels after the first hour following allium cepa administration which they attributed to the glucogenic effects of Allium cepa. The study authors noted that this could counteract the common side effect, hypoglycemia of many antidiabetic agents.

They also noted that the sample size in their study was too small to reach concrete conclusions but it seems apparent that Allium cepa or red onion does indeed have glucose lowering properties which may be beneficial to those with diabetes.

People with high levels of alpha-carotene in their blood, that is, those who eat lots of fruit and vegetables, have a smaller risk of dying early and are more likely to live longer than others, researchers from the CDC (Centers for Disease Control and Prevention), Atlanta, Georgia wrote in the journal Archives of Internal Medicine. Alpha-carotene, beta-carotene and lycopene are carotenoids and are found in plants and microorganisms. They can counteract the oxygen-related damage to DNA, fats and proteins which contribute to the development of cancer, heart disease and other chronic illnesses.

Humans get carotenoids either from some fruit and vegetables, antioxidant supplements, or both. An example of an alpha-carotene rich fruit is cantaloupe melon.

The following vegetables are rich in alpha-carotene:

* Yellow-orange vegetables
– Carrots
– Sweet potatoes
– Pumpkin
– Winter squash
* Dark-green vegetables
– Broccoli
– Green beans
– Green peas
– Spinach
– Turnips greens
– Collards
– Leaf lettuce

The authors explain that consuming plenty of fruit and vegetables is linked to less risk of developing chronic diseases. However, no randomized controlled trials have ever linked this to beta-carotene supplements.

They wrote:

“Therefore, carotenoids other than beta-carotene may contribute to the reduction in disease risk, and their effects on risk of disease merit investigation.”

Chaoyang Li, M.D., Ph.D., and team examined the relationship between risk of death and alpha-carotene consumption in 15,318 men and women aged 20 or more – they had all taken part in the Third National Health and Nutrition Examination Survey Follow-up Study. Between 1988 and 1994 they provided blood samples and had medical examinations, and were then followed up at the end of 2006 to find out what the causes of death of those who had died were.

The researchers found that:

* 3,810 study participants died
* Those with 2 to 3 micrograms per deciliter of alpha-carotene in their blood had a 23% lower risk of dying compared with those whose levels were between 0 and 1 micrograms per deciliter
* Those with 4 to 5 micrograms per deciliter of alpha-carotene in their blood had a 27% lower risk of dying compared with those whose levels were between 0 and 1 micrograms per deciliter
* Those with 6 to 8 micrograms per deciliter of alpha-carotene in their blood had a 34% lower risk of dying compared with those whose levels were between 0 and 1 micrograms per deciliter
* Those with 9 micrograms per deciliter of alpha-carotene in their blood had a 39% lower risk of dying compared with those whose levels were between 0 and 1 micrograms per deciliter

They were able to isolate certain illnesses and deaths from other causes and link them to alpha-carotene concentrations. Those with higher concentrations of alpha-carotene in their blood had a lower risk of dying from cardiovascular disease or cancer individually, as well as from all other causes.

The authors wrote:

“The association between serum alpha-carotene concentrations and risk of death from all causes was significant in most subgroups stratified by demographic characteristics, lifestyle habits and health risk factors.”

Although alpha-carotene and beta-carotene are chemically very similar, alpha-carotene appears to be better at undermining the growth of cancer cells in the skin, liver and brain, the researchers said.

They wrote:

“Moreover, results from a population-based case-control study of the association between the consumption of fruits and vegetables and risk of lung cancer suggest that consumption of yellow-orange (carrots, sweet potatoes or pumpkin and winter squash) and dark-green (broccoli, green beans, green peas, spinach, turnips greens, collards and leaf lettuce) vegetables, which have a high alpha-carotene content, was more strongly associated with a decreased risk of lung cancer than was consumption of all other types of vegetables.”

A good way to avoid dying early is to increase fruit and vegetable consumption, the authors concluded. They added that further research is needed to look into the health benefits of alpha-carotene.

“Serum Alpha-Carotene Concentrations and Risk of Death Among US Adults – The Third National Health and Nutrition Examination Survey Follow-up Study”
Chaoyang Li, MD, PhD; Earl S. Ford, MD, MPH; Guixiang Zhao, MD, PhD; Lina S. Balluz, MPH, ScD; Wayne H. Giles, MD, MS; Simin Liu, MD, ScD
Arch Intern Med. Published online November 22, 2010. doi:10.1001/archinternmed.2010.440