Eat the rainbow
Variety is the spice of life. And when it comes to nutrition, increasing the variety of foods we eat not only stops boredom, it also has great health benefits.
That’s why you’ll often find us urging you to ‘eat the rainbow’. Eating a variety of colorful fruits and vegetables is a great way to ensure that you are getting all of the nutrients that your body needs.
All fruit and vegetables are beneficial because they contain fibre and vitamins. However, different colours are associated with different phytochemicals that have unique health benefits. And checking if your plate looks monochrome or technicolor is a quick way to assess if you are covering all the bases.
In this blog, we take you through the rainbow and give you some ideas for colourful foods you can enjoy even if you are following a low-FODMAP diet.
Red
Perhaps the most obvious red food is tomatoes. In this fruit the red colour mainly comes from lycopene, a carotenoid and powerful antioxidant that has been shown to reduce inflammation and improve heart health. Diets rich in lycopene have been linked to a lower risk of heart disease and certain types of cancer.
Whilst fresh tomatoes are packed full of vitamins (especially folate, Vitamin C, and potassium), cooked tomatoes actually offer a higher dose of lycopene.
Tomatoes also contain beta-carotene and gamma-carotene, which are pre-cursors of vitamin A, another powerful anti-oxidant.
Tomatoes can be tricky if you are following the low-FODMAP diet and susceptible to fructose, but 3 cherry tomatoes, 100g of canned tomatoes or 2 tabelspoons of tomato puree are all low FODMAP serving sizes.
We can’t write about red fruit without a special mention for strawberries - a low FODMAP summer favourite. Their red colour comes from anthocyanins which have great antioxidant properties. Callistephin is the dominant anthocyanin pigment in red strawberries and what makes them look as red as they do. Strawberries are also a fabulous source of Vitamin C. 65g or 6 medium strawberries is a low FODMAP serving size. We added real dried Aussie strawberries to our Strawberry Shakes and Berries+ Daily Gut Health Boost so that you can get a taste of summer all year round.
Another A grade red fruit is red capsicum or red pepper. A moderate amount (43g) is low in FODMAPs. Orange capsicums have a slightly smaller low FODMAP serving size at 38g, but are by far the richest natural source of zeaxanthin, which can help prevent macular degeneration… which brings us neatly to the second colour in the rainbow…
Orange
The obvious posterchild here is the carrot. Cheap and ubiquitous, carrots are also a fabulous source of the orange pigments alpha- and beta-carotene, which are a great source of Vitamin A.
This nutrient promotes good vision and is important for growth, development, and immune function.
Carrots also contain biotin, Vitamin K1, potassium and Vitamin B6.
Carrots are a great staple of the low FODMAP diet - carrots remains low in FODMAPs up to a serving size of 500g. You can add them to many styles of dishes from salads to stews. We have a fabulous heirloom carrot recipe you may want to try.
Pumpkins are another good source of carotenoids, but can be tricky for fodmappers. Butternut pumpkin is low FODMAP at 45g. If you can source it, Japanese or Kabucha pumpkin has a larger low FODMAP serving size of 75g.
Turning to fruit, oranges - are one of the few fruits with a substantial low FODMAP serving size. A medium orange or a peeled mandarin are both low in FODMAPS. They contain many different carotenoids including pre-cursors for Vitamin A. They are also rich in vitamin C, with a single orange providing up to 92% of your daily needs. Vitamin C is important for keeping your skin, bones and connective tissue healthy as well as helping your body to absorb iron. It is also an important antioxidant and helps boost the immune system.
Oranges are great on their own or in a salad with other fruits or vegetables - here’s our favourite example.
Other delicious orange options include Mango, which again is a good source of beta-carotene, but a low FODMAP amount is just 1/5 of a cup. Melons also contain beta-carotene. Cantaloupe melon (3/4 cup is low FODMAP) contains more beta-carotene than honeydew (1/2 cup is low FODMAP).
If you are looking for a tropical fruit fix with a large low FODMAP serving size, try papaya, which has flesh ranging in colour from yellow through orange to red depending on the amount of different carotenoids. The major colourful chemical in the pulp of red-fleshed papaya is lycopene, while the major carotenoids in the yellow-fleshed papaya are beta-carotene and beta-cryptoxanthin. Papaya’s flavour is enhanced by a squeeze of lime juice and it has a substantial low FODMAP serving size - 1 cup.
Yellow
Carotenoids can also be responsible for the yellow colour in some vegetables.
A good yellow option for this time of year is the swede (some people know it as a rutabaga).
It is a round root which has a purple skin, but the flesh is thick and yellow in color.
I love it in a traditional lamb-based Irish stew, but it works just as well in a beef stew too.
The yellow colour in yellow potatoes comes from a chemical called anthoxanthin, which helps the immune system. Other veggies containing anthoxanthin are turnips, parsnips, mushrooms, ginger, cauliflower, onions and garlic. Stick to 75g of turnip, 75g of parsnip, 75g of oyster mushrooms, and the ginger, but skip the cauliflower, onions and garlic if you are fodmapping.
Green
Green leafy vegetables are mainly green due to the chlorophyll they contain. Chlorophyll can act as an antioxidant, but green veggies are also packed with a wide range of beneficial fibre, vitamins, minerals and other phytochemicals.
We are big fans of spinach. It has a substantial low FODMAP serving size - 75g.
Spinach is one of the richest dietary sources of quercetin an antioxidant that may ward off infection and inflammation. Spinach also contains lutein and zeaxanthin, both important for eye health. It also contains kaempferol and nitrates, plus magnesim, iron and calcium.
The cruciferous vegetables including cabbage, cauliflower, broccoli, kale and bok choy contain a group of substances known as glucosinolates, which are sulfur-containing chemicals. These chemicals don’t have much effect on colour, but are responsible for the pungent aroma and bitter flavor of cruciferous vegetables.
During food preparation, chewing, and digestion, the glucosinolates are broken down to form biologically active compounds that have been studied for their anti-cancer effects. However, whilst studies in animals have been promising, results in humans have been mixed and more research is needed.
These veggies are also often high FODMAPs - but some of the best options for fodmappers are cabbage (75g), brocolli heads (75g) or broccolini stalks (90g).
When looking at fruit, green usually implies unripeness, but Kiwi fruit are different.
The green colour of their flesh is from chlorophyll, which doesn’t break down as they ripen like in other fruit (no one is quite sure why). It may be because the main distributor of their seeds in the wild are monkeys, who can easily spot Kiwi fruit against their leaves. Birds and smaller herbivores find it easier to find brighter, red or yellow fruit. Some birds even sequester the carotenoids they eat in their plumage and use it as as a mating signal to females.
Kiwi fruit are chock full of Vitamin C and gut-friendly fibre and luckily two kiwi fruit per meal meet low FODMAP cut-offs.
We love this fruit so much that it is a key component in both our Greens+ and Berries+ Daily Gut Health Boost options.
Blue, Indigo and Violet
Things get a bit messy towards the far end of the rainbow. Truth be told I’m not really sure how these blues and purples all divide up. I mean, Google tells me that indigo is actually blue.
Whatever the exact colour name, beautiful purple, red, blue and black berries contain a wide variety of bioactive compounds. These include phenolic acids, and flavonoids, such as flavonols, flavanols, and anthocyanins. These are thought to lower blood pressure and impove cardiovascular health and may also lower the risk of dementia.
It is typically the anthocyanins that contribute the reddish-purple, blue and black colours. Animal studies have indicated that anthocyanins are beneficial to the gut microbiome: high anthocyanin intake improves gut health biomarkers (the ratio of Firmicutes to Bacteroide bacteria and the amount of short chain fatty acids) and can reduce the gut dysbiosis caused by obesity and a high fat diet. Anthocyanins may also have anti-cancer properties, although again more studies are needed in this space.
Blueberries, being one of the darkest berries have some of the highest anthocyanin levels. This is also the main contributor to their high antioxidant activity. They are also a good option for fodmappers - 125g or 1 cup of blueberries is low FODMAP. They are lovely on their own or with lactose-free yoghurt, but check out our blueberry muffin recipe for a great luchbox addition.
Acai berries also have high levels of anthocyanins and proanthocyanidins. Acai berries are also rich in fibre and heart friendly fatty acids, especially oleic, palmitic, and linoleic acids.
Acai berry pulp has not been tested by Monash for FODMAPs, but 20g of Acai berry powder is low FODMAP.
Raspberries contain anthocyanin, tannins and phenols and high levels of Vitamin C that together contribute to their antioxidant properties. This is slightly lower than that found in blueberries, but their fabulous flavour is extremely popular. Raspberries are the 4th most significant fruit product in the world.
Raspberries have long been used in traditional medicine and modern studies have indicated that raspberry extracts may inhibit proliferation of cancer cells.
A low FODMAP serving of raspberries is 1/3 of a cup per meal.
Grapes are also technically a berry (they have a fleshy fruit without a stone) and like other berries, red and black grapes contain anthocyanins and other polyphenols, which may help with blood vessel function and memory.
Dark grapes are particularly rich in the antioxidant polyphenol, resveratol. Resveratrol may help keep your heart healthy by relaxing blood vessels and lowering the risk of developing blood clots. The antioxidant and anti-inflammatory properties of resveratol also help protect against diseases like cancer, diabetes, and Alzheimer’s disease.
A low FODMAP serving of red grapes is 6 grapes per meal.
Finally, if you are looking for the benefits of anthocyanins, don’t forget the purple vegetables. Eggplants and red cabbage also contain anthocyanins. Low-FODMAP serving sizes are 75g of each.
In contrast, the purple colour found in beetroot comes from betalain pigments, which replace anthocyanins in some plants. Betalains are also healthy antioxidants.
As you can see, whilst we may label some foods as superfloods, all fruit and vegetables offer a variety of health benefits from fibre, vitamins, minerals and bioactive chemicals. Eat as many as you can (even if in low amounts if they contain FODMAPs) to reap the benefits.
Eating frozen or in-season fruit and vegetables can help cut down costs and up the nutrient value. Check out what’s in season now here.
Written by: Dr Mary Webberley, Chief Scientific Officer at Noisy Guts. Mary has a background in biology, with two degrees from the University of Cambridge and post-doctoral research experience. She spent several years undertaking research into the diagnosis of IBS and IBD. She was the winner of the 2018 CSIRO Breakout Female Scientist Award.