Most of you probably already know a little bit (or more) about the main nutrient groups, namely vitamins, minerals, carbohydrates, proteins, fats, and water. However, what do you know about phytonutrients?
Phytonutrients or phytochemicals are naturally occurring compounds in plants. Phyto is the Greek word for ‘plant’. There can be found thousands of phytochemicals in fruits, vegetables, grains, legumes, and herbs. Tomatoes alone, for example, contain about 10,000 different phytochemicals. Phytochemicals play an important role in plants’ world. They help plants to defend environmental stressors. They also give them color, distinctive tastes and smells, and control essential functions of growth and reproduction. Phytonutrients are also thought to promote human health, as they can also help people fight disease. In the human body, phytonutrients stimulate enzymes that help the body get rid of toxins, boost the immune system, improve cardiovascular health, promote healthy estrogen metabolism, and stimulate the death of cancer cells. These powerful little molecules can impact our health in amazing and surprising ways. Studies show that, for example, people who eat more phytonutrients-rich foods have reduced risk of chronic diseases such as diabetes, heart disease, cancer, and many other health conditions.
What do they do in plants?
Phytochemicals are produced by plants to protect them from harmful agents such as insects and microbes as well as stressful events such as ultraviolet (UV) irradiation and extreme temperatures. They also attract beneficial birds and insects that promote pollination, germination, and seed dispersal. Among other things, phytochemicals give plants their color, flavour, and smell.
Phytonutrients and color of food
The cells of plants have small water sacs called vacuoles, and inside of these vacuoles are two special types of pigments.
Flavonoids – especially the type of flavonoids called anthocyanins – are the first type. Anthocyanin pigments are responsible for the reds, blues, and purples found in food. Other types of flavonoid pigments, called flavones and flavonols, provide foods with some of their vibrant yellow colors. Scientists have identified more than 3,000 different flavonoids in the plant food world.
Betalains are the second type of pigment found in the plant vacuoles. They are nitrogen-containing pigments, divided into betacyanins – which give food varying shades of violet, and the betaxanthins – which contribute to different shades of yellow in food.
In addition to the small water sacs in plants cells, there are other specialized components called plastids. There are two basic types of plastids: chromoplasts and chloroplasts. Inside the chromoplasts are the carotenoid pigments. The carotenoid group contains more than 600 different color-providing substances. Carotenoids include such carotenes as alpha-carotene, beta-carotene, gamma-carotene, and lycopene, as well as such xanthophylls as astaxanthin, canthaxanthin, cryptoxanthin, and zeaxanthin. Carotenoids are light-absorbing pigments, which means that they help trap the sunlight and convert it into chemical energy. Many of the orange and yellow pigments in food, and sometimes even some of the red pigments, are provided by carotenoids in the plant’s chromoplasts.
Chlorophylls, as many of you already know, give plant foods their vital green colors, and they are plant’s primary mechanism for trapping sunlight and transforming it into cell fuel.
Interesting fact: Sometimes a food contains so much chlorophyll in its chloroplasts that the carotenoid colors cannot be seen with a naked eye.
Phytonutrients and the taste of food
The food taste of plants also depends on phytonutrients, especially on the two categories – terpenoids and phenylpropanoids.
Terpenoids are responsible for some of the bitter and more astringent taste. Darjeeling tee, for example, is rich in terpenoids. Carrots are another example.
The phenylpropanoids are also well-known for their taste-providing qualities. In this category are the hydroxycinnamic acids that get released from grapes during a wine pressing.
The phytonutrient tannins, for example, are often responsible for the bitter taste. Tannins are cousins to flavonoids: both are polyphenolic substances and both involve thousands of different compounds that are sometimes unique to a small number of foods with antioxidant and cancer-protective properties. Some of the better known cancer-preventive substances like garlic acid, caffeic acid (in the coffee bean), and their derivatives are made from tannins.
Phytonutrients and the smell of food
Here we can mention the terpenoid category of phytonutrients which gives the aromas of essential oils such as lavender oil or bergamot oil (the distinctive aroma-producing component in Earl Grey tea) and the rich aroma of a Muscat wine. The phenylpropanoid phytonutrients are another category responsible for the aroma of foods. Included in this category is the unique smell of cloves as well as the distinct aroma of different coffees.
Another example are the sulphur-containing compounds. The best known source are rotten eggs, whose yolks are rich in unique sulphur compounds. The smells of chopped onions or crushed garlic are derived from sulphur metabolism. Other foods known for their sulfur-containing compounds are the cruciferous vegetables (broccoli, cabbage, cauliflower).
It’s interesting to note that how we prepare our food makes a difference in the sulfur-containing phytonutrients. When sulfur-containing foods like raw garlic or raw onions are sliced (or chopped, crushed, chewed), enzymes in the food become activated and start converting some sulfur compounds into other forms. This process also takes place when cruciferous vegetables like cabbage or broccoli get chopped. The result is an increase in many of the sulfur-containing phytonutrients that have been linked to different aspects of health improvement, including cancer prevention.
Benefits of phytonutrients for human health
Different phytochemicals have different reactions in the body. One may neutralize a carcinogen, while another may carry it away. Still another might act as an antioxidant to handcuff a free radical and keep it from roaming. Of great importance are the phytochemicals that stimulate the body’s own enzymes to destroy carcinogens before they have the chance to begin their damage.
Researchers have found that phytochemicals have the potential to stimulate the immune system, prevent toxic substances in the diet from becoming carcinogenic, reduce inflammation, prevent DNA damage and aid DNA repair, reduce oxidative damage to cells, slow the growth rate of cancer cells, trigger damaged cells to self-destruct (apoptosis) before they can reproduce, help regulate intracellular signaling of hormones and gene expression, and activate insulin receptors.
The primary benefits of phytonutrients lie in their abilities as antioxidants. Antioxidants block the action of free radicals, which can damage cell contents and membranes. Antioxidants are also a powerful aid to the immune system. With their help, the body is far better equipped to defend itself from free radicals. Some free radicals are also known carcinogens (cancer-causing substances), such as tobacco smoke, radiation, and air pollution. With their antioxidant activities phytonutrients have the ability to protect the body from cancer. Cancer is a category of disorders characterized by cells that have mutated and begin to reproduce themselves in an uncontrolled fashion. Under normal circumstances, the body’s natural defense system would attack such cells and, hopefully, destroy them. If the body’s natural killer cells are not successful, however, cancerous cells continue to reproduce wildly and, eventually, spread to other parts of the body. Phytochemicals like the catechins found in green tea act to prevent cell mutation and keep cells reproducing normally. Allyl sulphides, found in garlic and onions, trigger enzymes that help to rid the body of carcinogens before damage to the cell can be done. Capsaicin, which makes peppers spicy, may help protect DNA from carcinogens.
Cancer is just one example of a disease caused by free radical damage; cardiovascular disease is another. Consumption of phytonutrient-rich foods is linked to reduced risk of cardiovascular disease. One meta-analysis, for example, suggested that the risk of coronary heart disease would decrease by 4% for each portion per day of fruits and vegetables added to the diet. Some of the best-researched phytonutrient-rich foods linked to reduced risk of cardiovascular disease are soy, cocoa, black and green tea. There’s a wide range of health benefits associated with the consumption of these foods, including lowering blood pressure, reducing inflammation, increasing HDL cholesterol while decreasing LDL oxidation, dilating blood vessels and decreasing the tendency of the blood to form clots. Cocoa, for example, was found to improve endothelial function by dilating blood vessels.
Inflammation in the body can be hard to detect, yet it slowly attacks healthy tissues in the brain, arteries, and joints, leading to a large number of different health challenges. There are about 20 known anti-inflammatory phytochemicals, including apigenin (found in celery stalks and seeds), which can help reduce pain and inflammation from a variety of disorders including gout. Other important foods that contain inflammation-fighting phytochemicals are blackberries, cherries, raspberries, and strawberries. Phytonutrients in blueberries help the body to repair damage already caused by inflammation. There is also scientific evidence that some phytochemical compounds in plants have been used for the management of osteoarthritis due to their antiinflammatory properties.
One of the most-researched phytonutrients is resveratrol (found in red grapes, berries). Resveratrol has protective effects against inflammation, cancer and aging. It could improve the aging of human skin by influencing the human skin gene expression and mRNA levels.
Intestinal health support
Phytoestrogenes such as isoflavones, lignans, and elligitannins are polyphenols that could modulate the gut microbiota contributing to intestinal health. Other natural compounds derived from plants foods such as epigallocatechin gallate, naringenin, ellagic acid, resveratrol, quercetin, and curcumin are used as dietary supplements to prevent and treat gastrointestinal chronic diseases, such as peptic ulcer disease and inflammatory bowel disease (IBD). In addition, the gastroprotective effect of apples, grapes, green tea, and pomegranate are linked to their polyphenols, such as curcumin, quercetin, resveratrol, gallic acid. According to some clinical studies, these bioactive compounds could act in the gastric mucosa through different molecular and intracellular mechanisms as an antioxidant, anti-inflammatory, and wound healing agent.
Hormonal health support
Phytochemicals may also influence hormonal function. An example of this would be the isoflavones found in soy and the lignans found in flax. These can mimic estrogen in the body, in many cases blocking estrogen receptor sites, diminishing estrogen’s effects on certain tissues.
There are also enzymes in the liver that can make estrogen less effective. These enzymes can be up-regulated by indoles, a type of phytochemical found in cruciferous vegetables.
Antibacterial and antiviral properties
Most likely you have heard of the garlic’s antibacterial properties. Responsible for that is allicin, a phytochemical found in garlic. Many other phytonutrients have antibacterial and antiviral abilities. For example, anthocyanins (red, purple, and/or blue plant pigments) found in many fruits, can actually prevent the adhesion of pathogens to cell walls. Thus cranberries can help prevent urinary tract infections.
Skin protection from the sun
One of the best-researched plant components with photoprotection qualities are carotenoids, especially beta-carotene and lycopene. These two exist in higher levels in the skin, and can absorb UV rays. In plants and other photosynthetic organisms, carotenoids collect certain wavelengths of light as part of photosynthesis, providing some protection for these organisms as well. Carotenoids in the skin likely have a similar protective role.
In addition to absorbing light, carotenoids also aid in protection against sun damage through their antioxidant properties. They can inhibit lipid peroxidation, attenuate DNA-damage, and reduce inflammation.
Carotenoids are not the only phytochemicals that protect against sun damage; polyphenols and phenolics also provide photoprotection through UV-absorption, anti-inflammatory properties, DNA repair ability, and antioxidant ability as well.
The flavonoids may protect against UV-caused skin damage. In one small study, consuming 4 – 6 g of cocoa for one week led to a statistically significant increase in photoprotection. Another small study found that consuming 20 g of high-flavanol chocolate for 12 weeks led to a reduction in sunburn risk, while a group that consumed low-flavanol chocolate had no change.
One study looked at coffee and polyphenol intake in non-smoking, healthy females with moderate sun exposure. Those with higher consumption of coffee (which is rich in polyphenols) and polyphenols from all sources found a significant reduction in pigmented spots on the face, a marker for photoaging.
A summary of the different phytonutrient colors’ health benefits with food sources examples:
The phytonutrients associated with red foods have been linked to reducing the risk of certain types of cancer as well as their heart, brain, liver and immune system benefits.
- Sweet red peppers
- Red bell peppers
- Red onions
- Blood oranges
- Pink grapefruit
The phytonutrients found in these foods have been linked with reducing the risk of cancer, having an anti-inflammatory benefit, balancing hormones and protecting the brain, heart, liver and skin.
- Bean Sprouts
- Bell peppers
- Bitter melon
- Bok Choy
- Brussels Sprouts
- Green Beans
- Green Peas
- Green Tea
- Green leafy vegetables
- Snow Peas
Yellow foods have been strongly associated with their anti-inflammatory and anti-cancer effects. The phytonutrients found in yellow foods have been associated with brain, heart, eye and skin health.
The phytonutrients in orange foods have been linked with supporting the immune system, skin health, eye health, reducing inflammation, reducing the risk of heart disease and cancer prevention and support.
- Yellow Bell Peppers
- Ginger root
- Butternut squash
- Sweet potato
- Orange bell peppers
- Cantaloupe melon
- Butternut squash
Phytonutrients in these foods have been linked with their anti-cancer effects, cardiovascular health, anti-inflammatory and anti bacterial, yeast and parasitic activity.
- Whole grains
- Spices such as cinnamon, clove etc
- Legumes like chickpeas, beans, peas, cashews
Phytonutrients in these foods have been linked with having anti-cancer, anti-inflammatory properties as well as protecting the brain, heart and general vascular system.
- Purple cabbage, cauliflower, carrots, kale
A few tips on how to get more phytonutrients in your diet:
- Eat the rainbow. Include a variety of colors of plant-based foods in your meals.
- Try to incorporate fruit or vegetables with every meal, or at least 3 times a day.
- Snack on vegetables and fruits.
- When making a smoothie with fruits, add 1-2 handfuls of spinach (or other greens) or frozen cauliflower and zucchini.
- Add as much vegetables as possible to soups. You can also blend them if you are not a veggie lover.
- Eat seasonal foods, but also experiment with new phytonutrient-rich foods.
- Keep in mind that certain phytonutrients in foods can become more absorbable after cooking; this includes foods such as carrots, mushrooms, asparagus, spinach, broccoli, cabbage, peppers, tomatoes and potatoes.
- You can increase the absorption of the phytonutrients by adding a little fat/oil such as ghee or olive oil, so that is worth considering when serving up a salad or a colourful side dish of these healthy phytonutrient rich foods.
- Choose darker foods which are typically richest in phytonutrients.