English researchers determined whether activation of Nrf2 by sulforaphane in broccoli could prevent vascular damage in humans. Nrf2 activates protective antioxidant enzymes such as transketolase and glutathione s- transferase (GST) and detoxifying enzymes such as quinone reductase (QR).
Method
Human endothelial cells - cells that line all blood vessels- were grown in high and low glucose concentration were treated with sulforaphane.
Results
- Sulforaphane activated Nrf2 which in turn triggered the antioxidant expression of transketolase and glutathione reductase. Transketolase is an enzyme required for glycolysis - the efficient breakdown of carbohydrates and glucose into energy.
- Sulforaphane prevented high blood glucose or hyperglycemia by suppressing the activation of the hexoamine and protein-kinase pathways. The hexoamine pathway causes insulin resistance, while the protein-kinase pathway promotes atherosclerosis (hardening of the arteries), and abnormal cell signaling.
- Sulforaphane suppressed cellular formation and accumulation of methylglyoxal, a poisonous by product of glucose metabolism. Methyglyoxal impairs insulin signaling and alters the activity of a gene that controls blood vessel growth. It also disrupts the activities of others genes.
Conclusion
Activation of Nrf2 by sulforaphane from broccoli may prevent biochemical dysfunction of endothelial cells triggered by hyperglycemia in susceptible persons. The study was published in the 2008 issue of Diabetes.
Broccoli: the "Wonder" Vegetable
Broccoli, Brassica oleracea var. botrytis-italica, or "broccolo" Italian meaning "cabbage sprout" is the richest source of sulforaphane - an isothiacyanate, antioxidant, and stimulator of natural detoxifying enzymes. It occurs in plants bound to a glucose molecule called "sulforaphane glucosinolate". Sulforaphane is released only after eating.
The best way of preparing broccoli is steaming using small amounts of liquid. This prevents water-soluble substances including sulforaphane from leaching into the cooking liquid.
Never Microwave Broccoli. Microwaves destroy 97% to 74% of the antioxidants, detoxifying enzymes, and heat-sensitive vitamins such as vitamin C in the microwave.
Recommended Daily Allowance of Fruits and Vegetables: Health Canada recommends that Canadians consume a variety of foods in moderate amounts. To obtain maximum benefits from fruits and vegetables, Canada's Food Guide recommends the following:
- Children (Ages 2-13) 4-6 servings
- Teens (Ages 14-18) 7-8 servings
- Adults (Ages 19-50) 7-10 servings
- Adults (Ages 51 and over) 7 servings
- One serving of cooked broccoli is 1/2 cup
Nutritional Content of One Cup Steamed, Unsalted and Drained Broccoli
- Vitamin C 125 mg
- Vitamin K 155 micrograms
- Vitamin A 2,280 IU
- Folate 94 micrograms
- Dietary Fiber 5 grams
Broccoli contains appreciable amounts of Manganese, Tryptophan, Potassium, Vitamins B1, B2, B3, B5 or Pantothenic Acid, Iron, Calcium, Vitamin E, and Zinc.
WarningEating too much broccoli may contribute to iodine deficiency that may lead to toxic goiter (enlargement of the thyroid gland). Broccoli contains goitrogens - plant chemicals that interfere with iodine metabolism. In pregnant women, iodine deficiency impairs fetal development causing extreme mental and physical retardation known as "cretinism." Cretinism affects about 6 million people wordwide. Early diagnosis and treatment prevents cretinism. Delayed or lack of treatment contributes to a low IQ, as low as 20 (Average IQ: 100). Children with mild iodine deficiency have goiters and perform poorly in school.
References
- Xue et al. "Activation of NF-E2-related factor 2 reverses biochemical dysfunction of endothelial cells induced by hyperglycemia linked to vascular diseases." Diabetes 2008; 57:2807-2817
- Vallejo F et al. "Phenolic compound content in edible parts of broccoli inflorescens after domestic cooking" J Sci Food Agric 2003;51:3029-3034
- Iodine Deficiency. Understanding Nutrition, 9th Edition, Whitney EN & Rolfes SR Wadsworth/Thomson CA 2002 pp: 445-657
 |
 |
 |
 |
