Fruits and vegetables contain important nutrients that can help to prevent chronic diseases such as cancer and cardiovascular disease. The phytochemicals in many fruits and vegetables have potent anti-inflammatory properties as well as high levels of antioxidants so it makes sense to get plenty in our daily diet. But how much should we be eating to get the benefits?
The National Cancer Institute recommends 5–9 servings of fruits and vegetables daily and the British Heart Foundation also recommends 5 servings of fruit and vegetables daily. This is quite easy to do given how small a serving actually is. For example:
● ½ cup steamed vegetables
● 1 cup of leafy vegetables
● 1 medium size piece of fruit
● ½ cup of chopped fruit.
With this in mind, a daily consumption of 5 servings of fruit and vegetables could be comprised of the following:
● 1 cup of steamed broccoli (2 servings)
● 1 cups of leafy vegetables such as kale or rocket. (1 serving)
● 1 apple (1 serving)
● ½ cup of strawberries (1 serving)
Generally speaking, it will take 2 cups leafy vegetables such as rocket, kale or spinach to equal 1 cup of vegetables such as broccoli or cauliflower. Its tempting to think that we could just eat 3 cups of strawberries or 5 apples a day and we are covered, but the idea is to eat a variety of fruits and vegetables to get a wide range of nutrients throughout the week. It keeps it interesting too.
The latest research on 10 a day
New research led by scientists from Imperial College London, found that although even the recommended five portions of fruit and vegetables a day reduced disease risk, the greatest benefit came from eating 10 portions a day which is equivalent to 800 grams.(1) This research was a meta-analysis where the researchers analysed 95 studies on fruit and vegetable intake. This included up to 2 million people from populations worldwide, and assessed up to 43,000 cases of heart disease, 47,000 cases of stroke, 81,000 cases of cardiovascular disease, 112,000 cancer cases and 94,000 deaths.
The results showed that eating 10 portions of fruit and vegetables or 800 grams per day, reduced the risks of chronic disease and premature death as follows:
With these types of studies, where risk is be measured, the risk has to be relative to something. This is known as relative risk. This is used to compare the risk between two different groups of people. In the research above, it is comparing people who eat a certain amount of fruit and vegetables compared to people who eat no fruit and vegetables. This is used extensively in medical research to see if belonging to one group increases or decreases your risks of developing a specific disease. Lets take a closer look at a couple of examples of the benefits of fruits and vegetables.
Not only are blackberries rich in vitamins and minerals, they are also very high in antioxidants and it is the anthocyanins in blackberries that give them their glossy, dark colour. It is these antioxidants that scavenge free radicals and reactive oxygen species (ROS) that play a major role in the aging process and chronic diseases. Blackberries have one of the highest antioxidant content of any food.
There is an increasing amount of research on berries and their cancer fighting properties, particularly blackberries. They are rich in cyanidin 3-glocoside (C3G), ellagic acid, lignans and the flavonoid myricetin which are all substances known for their anti-cancer properties. Cyanidin 3-glucoside or C3G, is an anthocyanin and blackberries contain a high level of this. 80 percent of anthocyanin in blackberries is C3G and studies have shown this to help protect against cancer as well as have cancer fighting effects.(2)
Ellagic acid is another potent ingredient in blackberries that has been shown to act as a chemo-preventive agent, inhibiting carcinogen bio-activation and cancer cell growth.(3) The synergy of these phytochemicals in blackberries maybe an effective preventative measure against cancer. It is early days on this research but it is well worth keeping an eye on developments here.
Broccoli is a member of the cabbage family and closely related to the cauliflower. These are known as cruciferous vegetables. It’s name is derived from the Latin word ‘Brachium’ which means branch or arm and this is reflected in its tree like shape. Broccoli has its roots in Italy where it is called ‘Broccolo’, meaning ‘cabbage sprout’ in Italian.
Broccoli is a super food, no doubt about it. A key bioactive compound that is thought to be responsible for much of the goodness of broccoli as an isothiocyanate called sulforaphane. There are many studies that support the protective properties of sulforaphane in many chronic inflammatory conditions as well as oxidative stress. A recent study published in the Journal of Inflammation in 2015, showed that the sulforaphane in broccoli can inhibit or significantly suppress the production of Nuclear Factor Kappa-B (NF-kB).(4) The results of this study demonstrate that a diet rich in phytochemicals from foods such as broccoli and other cruciferous vegetables is an effective way of controlling inflammation. This is particularly important for a disease like Crohn’s disease where diet can play a key role in relieving or exacerbating symptoms.
When it comes to established recommendations for cruciferous vegetables, there are no specific guidelines. One study showed that people who eat 3.7 cups of broccoli per week were 50% less likely to develop colorectal cancer than those who never ate broccoli.(5) While this study included many cruciferous vegetables, the main focus was on broccoli because it contains sulforaphane, and we already known that this is a potent inducer of carcinogen-detoxifying enzymes. In other studies on cancer risk, the suggestion is that adults should aim for at least 5 servings of cruciferous vegetables on a weekly basis. Note that this is 5 servings per week not per day!
The health benefits of broccoli and indeed all cruciferous vegetables are undisputed, however, obtaining an optimal amount of the nutrients contained in these vegetables such as sulforaphane, may be a challenge. Are you going to eat broccoli everyday? It is certainly possible if you absolutely love your greens but may be a challenge if your taste buds disagree. For those that don’t enjoy broccoli, there are extracts such as sulforaphane supplements that can be used to augment the diet. We’ll take a look at this and other anti-inflammatory supplements in a future article.
Of course, the recommendation is to get as much of our nutrients naturally through foods, however, I’m realistic and it is not always possible to consume the necessary amount of fruit and veg every day, particularly if we set our sights on 10 a day. That’s why a combination of fresh fruit and veg and supplements can work well together.
I also like to juice my fruit and vegetables as an easy way to consume more portions through the day. You might not like broccoli or kale on your dinner plate, but there are plenty of great smoothie recipes that include these vegetables and taste great.
With the evidence above and many more studies that support this, it really does seem that the old saying of 'eat your greens' is true. Well, not quite, I'd also add all the other colours of the rainbow too!
1. Fruit and vegetable intake and the risk of cardiovascular disease, total cancer and all-cause mortality–a systematic review and dose-response meta-analysis of prospective studies.
Int J Epidemiol dyw319. Published: 22 Feb 2017
2. Anthocyanin-Rich Blackberry Extract Suppresses the DNA-Damaging Properties of Topoisomerase I and II Poisons in Colon Carcinoma Cells. J. Agric. Food Chem., 2011, 59 (13), pp 6966–6973
3. Research progress on the anticarcinogenic actions and mechanisms of ellagic acid. Cancer Biol Med. 2014 Jun; 11(2): 92–100.
4. Effect of Sulforaphane on NOD2 via NF-κB: implications for Crohn’s disease. Journal of Inflammation 2015 12:6
5. Glutathione transferase null genotype, broccoli, and lower prevalence of colorectal adenomas. Cancer Epidemiol Biomarkers Prev. 1998 Aug;7(8):647-52.
Sports & fitness nutritionist, researcher and author on a mission to improve the human condition. Focusing on evidence-based and outcome-based nutrition, training, mindset & environment