How Smoothie Ingredients Affect Nutrient Absorption
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Dr. Rhonda Patrick uses a smoothie to make fruits and vegetables easier to include in her daily routine. In this clip from Dr. Rhonda Patrick's appearance on The Mel Robbins Podcast, she combines kale, blueberries, avocado, and optional protein and barley beta-glucan. A large observational study associated five healthy lifestyle factors, including a healthy dietary pattern, with an estimated 14 additional years of life expectancy for women and 12 years for men at age 50 compared with following none of the factors. [1]
Kale provides lutein and zeaxanthin, two carotenoids found in the retina and brain. Blueberries provide anthocyanins and other polyphenols. Randomized blueberry trials have reported improvements in selected cognitive measures across several populations, although the foods, doses, study durations, and tests have varied. [2] [3]
Avocado gives the smoothie a creamy texture and supplies fat that can help the body absorb carotenoids from vegetables. Small feeding studies found substantially greater absorption of lutein, alpha-carotene, and beta-carotene when avocado or avocado oil was added to a low-fat meal. Dr. Patrick also discusses separating bananas from polyphenol-rich berries because banana polyphenol oxidase reduced flavan-3-ol metabolite exposure in a small crossover study. Barley beta-glucan adds soluble fiber, and about 3 grams per day of sufficiently viscous oat or barley beta-glucan can modestly reduce LDL cholesterol. [4] [5] [6]
This clip is excerpted, with permission, from Dr. Rhonda Patrick's appearance on The Mel Robbins Podcast. Thank you to The Mel Robbins Podcast for allowing us to share it.
- ^ 10.1161/circulationaha.117.032047
- ^ Travica N; D'Cunha NM; Naumovski N; Kent K; Mellor DD; Firth J, et al. (2020). The effect of blueberry interventions on cognitive performance and mood: A systematic review of randomized controlled trials. Brain Behav Immun 85, .
- ^ Miller MG; Hamilton DA; Joseph JA; Shukitt-Hale B (2018). Dietary blueberry improves cognition among older adults in a randomized, double-blind, placebo-controlled trial. Eur J Nutr 57, 3.
- ^ Unlu NZ; Bohn T; Clinton SK; Schwartz SJ (2005). Carotenoid absorption from salad and salsa by humans is enhanced by the addition of avocado or avocado oil. J Nutr 135, 3.
- ^ Ottaviani JI; Ensunsa JL; Fong RY; Kimball J; Medici V; Kuhnle GGC, et al. (2023). Impact of polyphenol oxidase on the bioavailability of flavan-3-ols in fruit smoothies: a controlled, single blinded, cross-over study. Food Funct 14, 18.
- ^ Ms Wolever T; Rahn M; Dioum E; Spruill SE; Ezatagha A; Campbell JE, et al. (2021). An Oat β-Glucan Beverage Reduces LDL Cholesterol and Cardiovascular Disease Risk in Men and Women with Borderline High Cholesterol: A Double-Blind, Randomized, Controlled Clinical Trial. J Nutr 151, 9.
Mel Robbins: Dr. Patrick, you are going to teach us how you make the smoothie that you have every day. I see kale, blueberries, avocado, protein powder, and something that I cannot pronounce.
Dr. Rhonda Patrick: It is a beta-glucan powder made from barley.
Before we make the smoothie, I want to explain why I like to have one every day. Diet and lifestyle affect how we age and our life expectancy. Genetics matter, but lifestyle contributes substantially.
One large observational study examined five healthy lifestyle factors. At age 50, women who followed all five had an estimated life expectancy about 14 years longer, and men had an estimate about 12 years longer, than people who followed none. The factors were a healthy dietary pattern, not smoking, regular physical activity, limited alcohol intake, and a healthy body weight. These are population estimates, not guarantees for an individual.
The dietary pattern included four or five servings of fruits and vegetables each day. A cup of leafy greens counts as a serving. I use a smoothie because it makes those servings easier for me to get.
I add about three cups of kale. Kale contains lutein and zeaxanthin, magnesium, calcium, and vitamin K. Lutein and zeaxanthin are present in the retina and brain. Supplement trials do not show that kale prevents macular degeneration or cognitive decline, but kale is a nutrient-dense leafy green.
Next, I add frozen blueberries. I use about two and a half cups in this shared batch. Blueberries contain anthocyanins and other polyphenols. Small randomized trials have found improvements in selected cognitive measures in some young adults, older adults, and people with mild cognitive decline. The findings are not consistent across all trials or outcomes.
Mel Robbins: Why do you not add a banana?
Dr. Rhonda Patrick: Bananas are nutritious and contain potassium. I like them before a run. However, bananas contain polyphenol oxidase, an enzyme that can oxidize some polyphenols.
One small human study found lower flavan-3-ol metabolite exposure when participants consumed a high-polyphenol-oxidase banana smoothie. That does not mean that bananas cancel every benefit of blueberries or make a smoothie unhealthy. I choose not to combine them when my goal is to maximize polyphenol exposure.
I use avocado for a creamy texture. Its fat can also improve absorption of fat-soluble carotenoids from vegetables. Small acute feeding studies found substantially greater absorption of lutein, alpha-carotene, and beta-carotene when avocado or avocado oil was added to a low-fat meal. Avocado is not unique; other dietary fats can also improve carotenoid absorption. I use about half of an avocado.
Protein powder is optional. I add it on busy days when I might otherwise miss a meal or fall short of my protein goal. This serving provides about 24 grams of protein. The appropriate daily protein amount depends on body size, age, activity, diet, and health.
The barley beta-glucan is also optional. Beta-glucan is a soluble, fermentable fiber. Human trials show that about 3 grams per day of sufficiently viscous oat or barley beta-glucan can modestly lower LDL cholesterol. Preliminary human data on PFAS did not show a clear treatment-versus-control difference, so beta-glucan should not be described as a proven way to remove forever chemicals.
The spoken product dose in this clip is unclear. The captions appear to equate one gram with three tablespoons, then discuss three grams per day. The product label and audio must be verified before publishing a dose.
This blender jar is plastic. Laboratory work suggests that abrasive blending can release micro- and nanoplastic particles from some plastic containers. The amount depends on the material, equipment, food, temperature, and blending conditions. The study did not measure human absorption or health outcomes. A glass or suitable stainless-steel container is a reasonable preference when compatible with the blender.
Mel Robbins: The smoothie is very purple and creamy. The prebiotic fiber did not seem to change the texture.
Dr. Rhonda Patrick: This is a practical way for me to add fruit, leafy greens, dietary fat, and optional protein and fiber. It is my personal recipe, not a tested anti-aging treatment or a universal prescription.
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