Clean & Green: New guidelines for crafting a smoothie
April 03, 2024 by Joel Fuhrman, MD
Berries, greens, and seeds pack a nutritional punch; bananas are no longer recommended (to mix with berries)
Smoothies are a great way to increase your intake of important plant nutrients – plus they’re convenient, portable, and delicious. The problem is that if you use too much fruit – and not enough greens – they can turn into a ticking caloric time bomb. Plus, read on to discover why your smoothie should not combine bananas with berries.
The Art of Smoothie Crafting
When creating your smoothie, it’s useful to think of it as a meal. Just like you wouldn’t put a bunch of fruit and one kale leaf into bowl and call it a salad, you should be conscious of what you’re putting in the blender.
NUTRITARIAN TIP: If you’re new to smoothie-making, don’t “freeform” it. Start by following recipes from the Nutritarian Recipe Database until you understand the correct proportions. It’ll soon become second nature.
Here's how to make your smoothie a tasty nutritional powerhouse:
6 steps to building your perfect smoothie
1. Make it mostly greens
Use: about 2 cups of leafy greens. Kale or another leafy cruciferous green (arugula, cabbage, collards, bok choy) will add fiber and vital nutrients without adding unnecessary sugars. Lettuce is an option, too. Limit spinach and Swiss chard in smoothies because they are high in oxalate, which limits calcium absorption.
2. Choose your fruit wisely
Use one half to one cup of fruit. Focus on high-phytochemical fruits: Packed with antioxidants and low in sugar, berries or pomegranate arils add brilliant color and vibrant flavor. Use fresh or frozen. Oranges , frozen cherries, and frozen mango are also good choices.
3. Don’t forget the flax and chia seeds
Use 1-2 tablespoons. Include flax and/or chia seeds to get your omega-3 ALA, and enhance your smoothie with fiber, essential minerals, and protective phytonutrients including lignans, sterols and stanols.
4. Blend in the plant milk or water
For a creamy texture, unsweetened soy, almond or hemp milk can’t be beat. (Check the ingredients list to make sure the milk has no fillers, thickeners, etc.) No plant milk on hand? Water is fine.
5. Add in some extra flavor
Vanilla bean powder, cinnamon, fresh ginger or turmeric, lemon or lime juice, or unsweetened cocoa powder for flavor. You can also add mushroom powder for a boost of immune-supporting phytochemicals, nuts for extra satiety value, or a conservative dose of plant protein powder are all good options.
6. Don’t combine bananas with flavonoid-rich fruits
They add sweetness and creaminess, but they also contain an enzyme that breaks down beneficial flavonoids. See the section, The problem with bananas, below.
Products to explore:
Organic Mushroom Chai Superfood Powder ORDER
Mediterranean Stone Pine Nuts ORDER
Organic Pro-Boost Superfood Protein Powder ORDER
The Science Behind the Smoothie Guidelines
Remember that a smoothie should be a nutrient-packed breakfast, not a high-calorie, high-glycemic dessert. Since everything is blended, and no chewing is required, smoothies that are allor mostly fruit (especially those that include fruit juice) can cause people to consume too many calories and absorb the sugars too quickly. The extra fiber from the greens, combined with a smaller amount of fruit, will help limit the rise in blood glucose from the fruit.
Berries and pomegranate arils are some of the lowest-sugar fruits and are also rich in phytochemicals, such as flavonoids, which have a variety of antioxidant and anti-inflammatory effects.1-3 Cherries, like berries contain anthocyanins (a subcategory of flavonoids) oranges are rich in citrus flavonoids, and mango is rich in carotenoids.
Adding fats in the form of seeds and nuts adds satiety value, reduces the glycemic load of the smoothie, and enhances absorption of carotenoids from the greens.4 Because blending breaks up plant cell structures more efficiently than chewing alone, this also makes some nutrients more accessible for absorption.5
Bananas can add both sweet flavor and creaminess to a smoothie, but there are two reasons why I recommend not including them:
1. Bananas are higher in sugar and lower in beneficial phytochemicals than the other fruits.
2. Bananas are high in an enzyme that breaks down other beneficial flavonoids.
Recent research suggests that after blending, the polyphenol oxidase enzyme in bananas breaks down beneficial flavonoids that are also present in the smoothie. In the study, the concentration of epicatechin (a flavonoid) in the smoothie was reduced by half within about 10 minutes of blending, and epicatechin metabolite concentrations in the blood of human volunteers were much lower following an epicatechin-containing smoothie with compared to without banana.6
To maximize flavonoid bioavailability from berries, we should avoid combining berries with bananas. Beet greens and apples also contain polyphenol oxidase; at about one-half and one-sixth the concentration of bananas, respectively.6
In your smoothie, opt first for flax seeds and chia seeds. . Since omega-3 content is an important consideration, I recommend making up at least half of your daily nut and seed intake with high omega-3 ALA varieties: flax, chia, and hemp seeds, and walnuts. I also recommend taking an omega-3 DHA and EPA supplement daily.
Since flax and chia seeds are small and difficult to chew adequately without grinding them first, blending one tablespoon each into a smoothie is a great way to get your daily flax and chia. As you can see in the table below, flax seeds and chia seeds are much higher in this beneficial fat than any other nut or seed; they have more than twice as much omega-3 ALA as walnuts or hemp seeds. Pecans, which come in fifth, have less than one-tenth the omega-3 of walnuts.
Flax and chia are both high in omega-3 and relatively low in omega-6 compared to other nuts and seeds. Plus, they are rich in lignans, phytoestrogens with anti-cancer effects.
The essential omega-3 fatty acid ALA and the essential omega-6 LA both use the same pathway for conversion to eicosanoids, molecules involved in the inflammatory response. Increasing omega-3 ALA intake may limit the production of pro-inflammatory metabolites from omega-6 LA, which is also present in nuts and seeds.7
Using flax and chia seeds daily helps to balance out your omega-3 and omega-6 fatty acid intake, and hemp seeds and walnuts add some more omega-3 to your diet.
Omega-3 and omega-6 fatty acids in selected nuts and seeds8
I recommend limiting your intake of green smoothies to one daily. Don’t skip your daily salad. Also, chewing is important for dental health. Remember: the key to smoothies is to focus on vegetables and seeds while keeping fruits to a minimum. This approach ensures you get maximum nutritional benefits without overloading on sugars. Happy blending!
References
Li G, Ding K, Qiao Y, et al. Flavonoids Regulate Inflammation and Oxidative Stress in Cancer.Molecules 2020, 25.
Mahmoud AM, Hernandez Bautista RJ, Sandhu MA, Hussein OE. Beneficial Effects of Citrus Flavonoids on Cardiovascular and Metabolic Health.Oxid Med Cell Longev 2019, 2019:5484138.
Choy KW, Murugan D, Leong XF, et al. Flavonoids as Natural Anti-Inflammatory Agents Targeting Nuclear Factor-Kappa B (NFkappaB) Signaling in Cardiovascular Diseases: A Mini Review.Front Pharmacol 2019, 10:1295.
Brown MJ, Ferruzzi MG, Nguyen ML, et al. Carotenoid bioavailability is higher from salads ingested with full-fat than with fat-reduced salad dressings as measured with electrochemical detection.American Journal of Clinical Nutrition 2004, 80:396-403.
Parada J, Aguilera JM. Food microstructure affects the bioavailability of several nutrients.J Food Sci 2007, 72:R21-32.
Ottaviani JI, Ensunsa JL, Fong RY, et al. Impact of polyphenol oxidase on the bioavailability of flavan-3-ols in fruit smoothies: a controlled, single blinded, cross-over study.Food & Function 2023, 14:8217-8228.
Calder PC. Omega-3 fatty acids and inflammatory processes.Nutrients 2010, 2:355-374.
U.S. Department of Agriculture. Food Data Central [https://fdc.nal.usda.gov/]
Joel Fuhrman, M.D. is a board-certified family physician, seven-time New York Times bestselling author and internationally recognized expert on nutrition and natural healing, who specializes in preventing and reversing disease through nutritional methods. Dr. Fuhrman coined the term “Nutritarian” to describe his longevity-promoting, nutrient dense, plant-rich eating style.
For over 30 years, Dr. Fuhrman has shown that it is possible to achieve sustainable weight loss and reverse heart disease, diabetes and many other illnesses using smart nutrition. In his medical practice, and through his books and PBS television specials, he continues to bring this life-saving message to hundreds of thousands of people around the world.
Clean & Green: New guidelines for crafting a smoothie
April 03, 2024 by Joel Fuhrman, MD
Berries, greens, and seeds pack a nutritional punch; bananas are no longer recommended (to mix with berries)
Smoothies are a great way to increase your intake of important plant nutrients – plus they’re convenient, portable, and delicious. The problem is that if you use too much fruit – and not enough greens – they can turn into a ticking caloric time bomb. Plus, read on to discover why your smoothie should not combine bananas with berries.
The Art of Smoothie Crafting
When creating your smoothie, it’s useful to think of it as a meal. Just like you wouldn’t put a bunch of fruit and one kale leaf into bowl and call it a salad, you should be conscious of what you’re putting in the blender.
NUTRITARIAN TIP: If you’re new to smoothie-making, don’t “freeform” it. Start by following recipes from the Nutritarian Recipe Database until you understand the correct proportions. It’ll soon become second nature.
Here's how to make your smoothie a tasty nutritional powerhouse:
6 steps to building your perfect smoothie
1. Make it mostly greens
Use: about 2 cups of leafy greens. Kale or another leafy cruciferous green (arugula, cabbage, collards, bok choy) will add fiber and vital nutrients without adding unnecessary sugars. Lettuce is an option, too. Limit spinach and Swiss chard in smoothies because they are high in oxalate, which limits calcium absorption.
2. Choose your fruit wisely
Use one half to one cup of fruit. Focus on high-phytochemical fruits: Packed with antioxidants and low in sugar, berries or pomegranate arils add brilliant color and vibrant flavor. Use fresh or frozen. Oranges , frozen cherries, and frozen mango are also good choices.
3. Don’t forget the flax and chia seeds
Use 1-2 tablespoons. Include flax and/or chia seeds to get your omega-3 ALA, and enhance your smoothie with fiber, essential minerals, and protective phytonutrients including lignans, sterols and stanols.
4. Blend in the plant milk or water
For a creamy texture, unsweetened soy, almond or hemp milk can’t be beat. (Check the ingredients list to make sure the milk has no fillers, thickeners, etc.) No plant milk on hand? Water is fine.
5. Add in some extra flavor
Vanilla bean powder, cinnamon, fresh ginger or turmeric, lemon or lime juice, or unsweetened cocoa powder for flavor. You can also add mushroom powder for a boost of immune-supporting phytochemicals, nuts for extra satiety value, or a conservative dose of plant protein powder are all good options.
6. Don’t combine bananas with flavonoid-rich fruits
They add sweetness and creaminess, but they also contain an enzyme that breaks down beneficial flavonoids. See the section, The problem with bananas, below.
Products to explore:
Organic Mushroom Chai Superfood Powder ORDER
Mediterranean Stone Pine Nuts ORDER
Organic Pro-Boost Superfood Protein Powder ORDER
The Science Behind the Smoothie Guidelines
Remember that a smoothie should be a nutrient-packed breakfast, not a high-calorie, high-glycemic dessert. Since everything is blended, and no chewing is required, smoothies that are allor mostly fruit (especially those that include fruit juice) can cause people to consume too many calories and absorb the sugars too quickly. The extra fiber from the greens, combined with a smaller amount of fruit, will help limit the rise in blood glucose from the fruit.
Berries and pomegranate arils are some of the lowest-sugar fruits and are also rich in phytochemicals, such as flavonoids, which have a variety of antioxidant and anti-inflammatory effects.1-3 Cherries, like berries contain anthocyanins (a subcategory of flavonoids) oranges are rich in citrus flavonoids, and mango is rich in carotenoids.
Adding fats in the form of seeds and nuts adds satiety value, reduces the glycemic load of the smoothie, and enhances absorption of carotenoids from the greens.4 Because blending breaks up plant cell structures more efficiently than chewing alone, this also makes some nutrients more accessible for absorption.5
Sources:
Flavonoids Regulate Inflammation and Oxidative Stress in Cancer
Beneficial Effects of Citrus Flavonoids on Cardiovascular and Metabolic Health
Flavonoids as Natural Anti-Inflammatory Agents Targeting Nuclear Factor-Kappa B Signaling in Cardiovascular Diseases: A Mini Review
Carotenoid bioavailability is higher from salads ingested with full-fat than with fat-reduced salad dressings as measured with electrochemical detection
Food microstructure affects the bioavailability of several nutrients
Related: Eating berries reduces risk of heart attack
The problem with bananas
Bananas can add both sweet flavor and creaminess to a smoothie, but there are two reasons why I recommend not including them:
1. Bananas are higher in sugar and lower in beneficial phytochemicals than the other fruits.
2. Bananas are high in an enzyme that breaks down other beneficial flavonoids.
Recent research suggests that after blending, the polyphenol oxidase enzyme in bananas breaks down beneficial flavonoids that are also present in the smoothie. In the study, the concentration of epicatechin (a flavonoid) in the smoothie was reduced by half within about 10 minutes of blending, and epicatechin metabolite concentrations in the blood of human volunteers were much lower following an epicatechin-containing smoothie with compared to without banana.6
To maximize flavonoid bioavailability from berries, we should avoid combining berries with bananas. Beet greens and apples also contain polyphenol oxidase; at about one-half and one-sixth the concentration of bananas, respectively.6
Source:
Impact of polyphenol oxidase on the bioavailability of flavan-3-ols in fruit smoothies: a controlled, single blinded, cross-over study
The importance of seeds and nuts
In your smoothie, opt first for flax seeds and chia seeds. . Since omega-3 content is an important consideration, I recommend making up at least half of your daily nut and seed intake with high omega-3 ALA varieties: flax, chia, and hemp seeds, and walnuts. I also recommend taking an omega-3 DHA and EPA supplement daily.
Related: How omega-3 fatty acids support brain health
Since flax and chia seeds are small and difficult to chew adequately without grinding them first, blending one tablespoon each into a smoothie is a great way to get your daily flax and chia. As you can see in the table below, flax seeds and chia seeds are much higher in this beneficial fat than any other nut or seed; they have more than twice as much omega-3 ALA as walnuts or hemp seeds. Pecans, which come in fifth, have less than one-tenth the omega-3 of walnuts.
Flax and chia are both high in omega-3 and relatively low in omega-6 compared to other nuts and seeds. Plus, they are rich in lignans, phytoestrogens with anti-cancer effects.
Related: Fight breast cancer with flax and chia seeds
The essential omega-3 fatty acid ALA and the essential omega-6 LA both use the same pathway for conversion to eicosanoids, molecules involved in the inflammatory response. Increasing omega-3 ALA intake may limit the production of pro-inflammatory metabolites from omega-6 LA, which is also present in nuts and seeds.7
Using flax and chia seeds daily helps to balance out your omega-3 and omega-6 fatty acid intake, and hemp seeds and walnuts add some more omega-3 to your diet.
Omega-3 and omega-6 fatty acids in selected nuts and seeds8
Omega-3 (g/100 g)
Omega-6 (g/100 g)
Flax seeds
22.8
5.9
Chia seeds
22.8
5.9
Walnuts
9.08
38.1
Hemp seeds
8.68
28.7
Pecans
0.986
20.6
Sesame seeds
0.376
21.4
Pistachios
0.212
13.1
Macadamia nuts
0.196
1.3
Cashews
0.161
7.7
Almonds
0.003
12.3
Sources:
Omega-3 fatty acids and inflammatory processes
U.S. Department of Agriculture. Food Data Central
Smoothie Takeaways
I recommend limiting your intake of green smoothies to one daily. Don’t skip your daily salad. Also, chewing is important for dental health. Remember: the key to smoothies is to focus on vegetables and seeds while keeping fruits to a minimum. This approach ensures you get maximum nutritional benefits without overloading on sugars. Happy blending!
Joel Fuhrman, M.D. is a board-certified family physician, seven-time New York Times bestselling author and internationally recognized expert on nutrition and natural healing, who specializes in preventing and reversing disease through nutritional methods. Dr. Fuhrman coined the term “Nutritarian” to describe his longevity-promoting, nutrient dense, plant-rich eating style.
For over 30 years, Dr. Fuhrman has shown that it is possible to achieve sustainable weight loss and reverse heart disease, diabetes and many other illnesses using smart nutrition. In his medical practice, and through his books and PBS television specials, he continues to bring this life-saving message to hundreds of thousands of people around the world.