Why you should "eat the rainbow" for optimal health.
This guest post is written by Moe Brandi who holds an MSc in Food Innovation and Health and specializes in bioactive components in foods that improve human health. Her work centers around natural ingredients and a strong belief that food can be healthy, delicious, and gratifying at the same time.
We are increasingly losing diversity in our diets, though there are a wide range of edible plants for us to explore.
Unfortunately, out of around 300.000 known edible plant species today, humans only use about 200, and approximately 75% of the world’s food is generated from only 12 plants and five animal species.
The decline in plant genetic diversity is caused by a demand for uniform and high-yielding plant varieties to support a growing world population.
Our food sector is now more than ever favoring high production practices for greater food production.
Not to mention the use of antibiotics for growth of livestock, which may also give rise to changes and loss of species richness in our ecosystem as well as in our gut microbiome.
IntroductionA healthy ecosystem is often defined by its biodiversity - its richness of species. Likewise, a diverse human gut microbiome (the number of different types of bacteria) is generally a positive sign and well correlated with overall health. Right now, due to the loss in diet diversity as well as the popularity of restrictive “exclusion” diets in the western world limiting our food options, we are seeing that microbes are disappearing in our GI tract. This loss in species richness may contribute to several disease states like autoimmune, diabetes, obesity, autism, and many more (reference).
Your dietary beliefs, actual daily food choices, and eating patterns affect your well-being. It’s shown that the more diverse the diet, the more diverse (and adaptable to stress) the microbiome. Eating a variety of plants will not only feed a wider range of bacteria, but also give you a wider range of vitamins, minerals, and phytonutrients/polyphenols (i.e. chemicals with bioactivity produced by plants - offer potential health benefits to humans). In one study, people who ate more than 30 different plant types per week had more diverse gut microbiomes than those who ate 10 or fewer types of plants per week, no matter the type of diet prescribed (“American Gut Project” - project description). Though, while it was observed that people who eat more plants have a more diverse gut microbiome than people who don’t, it is still not clear if increasing a ‘healthy’ person’s microbial diversity from its current level will have a direct positive effect.
Effects from dietary changesAs mentioned, through our dietary choices, we are selecting ‘food’ substrates for some gut bacteria, providing them with competitive advantage over other gut bacteria. Whether you are excluding meat or specific types of plants and carbohydrates, introducing intermittent fasting periods etc, you are selecting for and favoring bacteria that can utilize the available nutrients for survival. Therefore, habitual diets throughout the year defined by lifestyle and palate will over time establish the gut microbiome profile of adults.
However, it is possible to change your gut microbiome rapidly with diet - even within just a few days of a big shift. Bacteria inherent to the foods that you eat (like the natural present microflora on fresh fruits and vegetables as well as fermented foods) may also have an impact and contribute to the changes. These quick changes may have had an evolutionary purpose. For ancient ‘hunters and gatherers’, an adaptive response to sudden shifts in the availability of foods defined by for example seasons and climate would ensure highest nutrient absorption from both familiar and novel foods.
Your body is indeed sensitive to dietary changes. This quick responsiveness emphasizes not only the importance of dietary choices in health and disease, but also the connection between certain bacteria and disease.
Our ability to tasteNow more than ever we have to think about exploring new plant varieties, bringing back the flavor-rich diet of our hunter gatherer ancestors. Talking about ‘diversity’ and food exploration also calls for a quick introduction to ‘taste’:
Taste receptors and signal transduction components have been identified for our five basic tastes: Sweet, umami (Japanese for ‘pleasant savory taste’), bitter, salty, and sour. Taste may be even more complex if we also consider the following qualities: ‘Fatty’, ‘kokumi’ (mouthful-ness), and ‘metallic’. Overall, by assessing food for these qualities, we are able to consume a healthy and nutritious diet as they all relate to a vital constituent of food: Sweet indicates carbohydrates, umami indicates proteins and amino acids, saltiness indicates important osmolytes like sodium chloride, bitter warns us about harmful and toxic compounds, sour tells us something about the freshness (so we can avoid rotten foods).
In theory, our basic ability to perceive flavors (taste and smell combined) and chemical components has not changed since our hunter-gatherer lifestyle. Actually, our ability to taste might have been one of our ancestors most important senses. From the taste and texture of foods, we are able to differentiate whether it will be healthy or harmful for us, the difference between life and death.
Bitter and astringent plant components (like glucosinolates in broccoli or tannins, a type of polyphenol, found in fruits and processed consumables like wine, tea, and coffee) often function as part of the plant’s defense strategy against predators, acting as either digestive inhibitors or toxins. For example, tannins inhibit iron absorption among other anti-nutritional characteristics. However, when eaten in moderation by humans, studies show that they have a number of positive physiological effects, including anti-carcinogenic and anti-oxidant properties. The importance of these bitter and astringent compounds has been confirmed in the primate diet of rhesus monkeys. These monkeys choose their foods based on phenolic content, not on total protein or carbohydrate content (reference).
Despite this, accepting or rejecting food is a complex process that not only depends on taste, but also on smell, tactile, and visual signals on top of memories of previous and similar experiences and social expectations. Nutrient intake and the introduction of new and different foods into your daily meals are therefore highly dependent on the palatability and hedonic value, individual and unique to each person.
You are what you eat, and so are the bacteria that live in your gutThe first to probably explore the value of culinary spices/pungency and also to use the phrase “you are what you eat”, was the french lawyer, politician, and gastronome: Jean A. Brillat-Savarin (1755-1826). Brillat-Savarin also shocked scientists by stating that the discovery of a new dish does more for human happiness than the discovery of a new star. He introduced new insights into the pursuit of healthy eating, the pleasure of spicy food (spice post), the value of culinary pungency and its relation to enjoyment of life in general.
All this relates to diversifying your diet: Variety in food ingredients as well as spices will transform your meals and give you that excitement that the same old meals with the same flavors, colors, textures, and forms simply can’t.
Tips to diversifying your diet:
1. Use seasons
In places with four distinct seasons, seasonal eating is easy to follow. It is indeed optimal to use seasons as a way of diversifying your diet. For example, you can use the seasons to make a list of produce that you can choose from. During winter, roots and tubers are in season, and warm, comforting food is something that we crave more (and that will do us much better) than a crisp and cold salad.
Some of the same base meals can also be changed according to season. For example all types of porridges, including risotto and daal, with varying toppings, cereals, and grains. Porridges can be both sweet or savory depending on your choice of spices and toppings (inspiration: groed menu). Below is a list of fruits and vegetables that you can choose from during fall season (September to November). Look up a seasonal list from your area and use it to diversify your diet:
Fruits (culinary definition)
- Berries (black berries)
Vegetables (culinary definition)
- Bok choy
- Brussel sprouts and cabbage
- Snap peas
- Greens (arugula, collards, chard, kale, dandelion)
- Winter squash
2. The Mediterranean diet
This heart-healthy and gut-friendly diet is one of the best research-backed. The Mediterrenean diet is recommended by the WHO as sustainable, well-balanced, and nonrestrictive.
This broad diet includes a variety of vegetables, olive oil, whole grains, beans, seeds, and nuts. It does not exclude animal products, but suggests that you eat it in moderation with limited intake of red meat. Generally, this diet focuses on fats coming from olive oil, seeds, and nuts. The diet also takes into account other aspects, like the importance of sharing a meal together with family and friends, enjoying a glass of wine, and the use of spices to decrease the amount of salt needed.
3. Eating the rainbow
Thinking about fruits and vegetables (F&V) in ‘colors’ will bring you variety, a range of micronutrients attributed to each (natural) color, and beauty. Eating the rainbow is a fundamental healthy eating tip, ensuring diversity in your diet.
Phytonutrients, also known as polyphenols, are behind the colors of F&V - each color indicates the natural content of specific nutrients:
- Red F&V: Often includes lycopene and ellagic acids known as anti-carcinogenic and anti-diabetes compounds. Look for tomatoes, red peppers (C-vitamin source), berries like strawberry and raspberry, beets, watermelon, pomegranate, apples, red onions (source of quercetin as a compound to reduce blood sugar levels and the prebiotic inulin).
- Yellow to orange F&V: Rich in vitamin C (antioxidant, boosts immune function) and carotenoids like beta-carotene, a precursor of vitamin A in the body (important for vision). Look for citrus fruits, carrots, sweet potatoes and winter squash, orange and yellow peppers, pineapple, golden beets, papayas, mangos.
- Green F&V: Considered very healthy - rich in lutein and zeaxanthin (antioxidants, support eye health), iron (dark leafy greens), folate (B vitamin important for pregnant women), isothiocyanate (in cruciferous vegetables like broccoli), and isoflavones with phytoestrogen actions (found in edamame beans). Look for broccoli, leafy greens, asparagus, artichoke (source of the prebiotic inulin), avocado, kiwi.
- Blue and purple F&V: Rich in anthocyanins and resveratrol with anticarcinogenic, antioxidants, and longevity properties. Look for: Red cabbage, grapes, plums, prunes, figs, eggplant, black and blueberries.
- White and brown F&V: Protect against certain kinds of cancers, heart healthy choice, contains B vitamins. Look for cruciferous cauliflower, mushrooms, garlic (contains alliin) and onions, parsnips, jicama.
4. Follow plant based food blogs and get inspired!
Some of my favorite ones: