The brilliance of broccoli
The latest healthy eating advice puts a lot of emphasis on eating fruit and vegetables, recommending five or more portions a day or suggesting these food groups should make up around half of everything we eat, (see ‘Introducing Harvard’s Healthy Eating Plate‘).
Looking at the research, the evidence for the benefit of eating fruit and vegetables is overwhelming but it is particularly strong for vegetables that belong to the cruciferous or cabbage family. These vegetables, also known as brassicas, all have four-petal flowers which form a cross shape, hence the name cruciferous or “cross-bearing.” The group includes broccoli as well as Swiss chard, cabbage, Brussels sprouts, cauliflower, watercress, radish, rocket and kale. The health benefits are thought to be due to their high content of bioactive vitamins, minerals and phytonutrients. A detailed chart of the nutrient composition of broccoli can be found on WHFoods website, compiled from the latest ESHA Research Data.
BENEFITS FOR GROWTH AND DEVELOPMENT
Between the ages of 10 and 14yrs children enter their peak growth phase where physical and brain growth accelerates. Broccoli contains Calcium, Zinc, Phosphorus, Iron, Copper, Vitamin C and a wide variety of B Vitamins all of which are important for building healthy bones and muscle. It is also an important source of vitamin A, Folate, and Choline and contains a small amount of omega 3, important for brain growth and development.
One cup of Broccoli also contains 253% of the RDI for Vitamin K. Research has found that Vitamin K along with Vitamin A has an important role in the regulation and metabolism of Vitamin D, particularly during deficiency. Vitamin D is vital for bone development, promoting calcium absorption in the gut and maintaining adequate blood concentrations of both calcium and phosphate to build new bone. Without sufficient Vitamin D, bones can become thin, brittle, or misshapen. Vitamin D deficiency causes rickets in children and promotes osteoporosis in adults. Vitamin D is also important for new cell growth and differentiation. Many of the proteins that regulate cell proliferation, differentiation, and apoptosis are modulated at least in part by Vitamin D. Vitamin D status is often low in elite athletes in the UK and many teenagers have also been found to have insufficient levels particularly in the winter. Vitamin K is also vital for blood clotting being an essential part of the coagulation cascade, the series of chemical reactions required to stimulate the formation of a blood clot.
Cruciferous vegetables contain brassinosteroids, which are plant-derived chemicals structurally similar to human cholesterol-derived steroid hormones. Almost no data exist on the effects of brassinosteroids on people and the area is very new but early studies (mostly in rats) have shown that supplementing with brassinosteroids can have an anabolic effect, stimulating protein synthesis, inhibiting protein degradation, increasing muscle mass and boosting physical performance.
BENEFITS OF PHYTONUTRIENTS
During energy production glucose and oxygen that enter the mitochondria. 95-98% of the oxygen is converted to water but the remaining 2-5 per cent can generate free radical reactive oxygen species (ROS). Oxidative stress occurs when these free radicals outnumber an individuals antioxidant defence and in the past this has been thought to cause cell damage. During exercise there is an increase in free radical generation within the working muscles. Brassicas possess high levels of antioxidants and high amounts in the diet has been shown to prevent or delay some measures of cell damage. Broccoli carotenes, beta-carotene, lutein and zeaxanthin are powerful antioxidants as are Selenium, Vitamin A, Vitamin C, Vitamin E.
Over the last decade there has been a huge amount of research into the benefits of antioxidants in the diet and in particular their lowering effect on homocysteine levels, cardiovascular disease risk and diabetes occurrance but not all of the research is conclusive and increasingly scientists believe that some degree of ROS action may be beneficial. Antioxidants in foods may be important but there is certainly no strong evidence that supplementing antioxidants is necessary.
In sport antioxidants are used as supplements. Many sports nutritionists believe there is good evidence that eating a diet rich in antioxidant nutrients can reduce the markers of free radical damage caused by extensive sports training and competition but there is also increasing evidence that high antioxidant diets may lower training adaptation. One of the biggest confirmed benefits of antioxidant use in athletes, is the prevention of post exercise muscle soreness. One possibility currently being studied is using high antioxidant diets during competition but not necessarily during training. A review of the research on antioxidants can be found here and information on their potential benefits here.
100g of broccoli (just over 1 cup) contains 21 milligrams of omega-3s (in the form of alpha-linolenic acid (ALA)). In the UK we don’t have a recommended daily intake of omega3s but generally its accepted that we need at least 250mg/day. Broccoli doesn’t compare very well with good sources like mackerel (100g contains 1422mg) and ALA conversion into DHA or EPA is limited but the benefits of omega3 are huge and every little bit helps. A full list of the benefits of omega3s is vast. The human brain is 60% fat (a large part of which is DHA) and eating Omega-3 rich foods boosts brain growth and connectivity. Omega3 is also an integral part of cell membranes, affect the function of the cell receptors and are a structural part of many hormones. Omega3s have been found to be particularly beneficial to individuals on the autistic spectrum and in dyslexia. If you are interested in this area Fab Research have a fantastic resources section.
Vitamin A, also called retinol, helps your eyes adjust to light changes and helps keep your eyes, skin and mucous membranes moist. Vitamin A generally comes from animal foods, but some plant-based foods like broccoli contain beta-carotene which can be converted into bioactive Vitamin A. 100g of broccoli contains ~12% RDI.
I don’t really agree with the term ‘functional food’ or ‘super food’ as a balanced diet should contain as wide a variety of foods as possible and not focus in on a few, but if you were to pick out one vegetable broccoli would certainly be a good one to choose.
Different commercial varieties of broccoli can vary widely in the quantities of nutrients they contain and the younger and fresher the broccoli the more phytonutrients it will have. Cooking also affects nutrient content, eating raw broccoli or steamed broccoli is possibly best as many of the nutrients are water soluble.
One note of caution before you gorge yourself on raw broccoli, like with most things, it is possible to have too much of a good thing. Whilst broccoli is loaded with beneficial nutrients it also contains goitrogens and nitriles. In large quantities, goitrogens can reduce thyroid activity and very high quantities of nitriles can have negative effects on the liver and kidneys.