May 24, 2022

Older Adults: Plant-Based Snacks Benefit Plasma Antioxidants and Microbiome

Results from a single-arm intervention
Eating 5 servings of smoothies and 3 servings of sesame-seed snacks a week can improve antioxidant capacity and gastrointestinal microbiota.

This article is part of our May 2022 Healthy Aging special issue. Download the full issue here.


Zhang JY, Lo HC, Yang FL, Liu YF, Wu WM, Chou CC. Plant-based, antioxidant-rich snacks elevate plasma antioxidant ability and alter gut bacterial composition in older adults. Nutrients. 2021;13(11):3872.

Key Takeaway

Four months of intervention with whole plant–based smoothies combined with sesame seed–based snacks have favorable effects on circulating antioxidant parameters in the elderly as well as measurable effects on the microbiome.


Open-label, single-arm intervention


Healthy and subhealthy older adults (N=42, average age 79.7 ± 8.6 years) in 2 senior living facilities operated by Yonghe Cardinal Tien Hospital, New Taipei City, Taiwan

Inclusion Criteria

Aged 65 years or more; resident of the facility for 2 or more months; healthy or subhealthy diagnosis by a physician. Subhealthy was defined as no existing pathology but existing prehypertension, being overweight or underweight, having serum lipids above the borderline, and/or having suboptimal renal or hepatic health.

Exclusion Criteria

Cancer, chronic obstructive pulmonary disease, severe disability, or dementia


Anthropometric measurements (weight, height, waist, and hip circumferences), body mass index (BMI), waist-hip ratio, complete blood count (CBC) with differential, lipid panel, blood urea nitrogen (BUN), creatinine, high-sensitivity C-reactive protein (hs-CRP), antioxidant enzymes in plasma and erythrocytes (thiobarbituric acid reactive substances, reduced glutathione, oxidized glutathione, total sulfhydryl groups, protein bound sulfhydryl groups, non-protein sulfhydryl groups), fecal samples (short-chain fatty acids [SCFA], acetic acid, propionic acid, butyric acid, total bacterial DNA, operational taxonomic units, alpha diversity, beta diversity). Investigators took measurements at baseline, 2 months, and 4 months.


There were 4 different plant-based smoothies with orange, green, dark green, and purple color. Investigators employed the following processes for all of them: “cleaning, pre-preparation, blanching, micro-processing, packaging, and frozen storage at -30 C.”

Each smoothie, 150 g, contained 1 exchange of vegetable (2 kinds), 1 exchange of fruit (2 kinds), and 1 exchange of nuts (145–186 kcal, 21–29 g carbohydrates, 4–5 g protein, 7 g lipid, 2.7–4.7 g  dietary fiber, and various minerals, vitamins, and phytochemicals, low saturated fats, no cholesterol, low sodium, low sugar, and 10%–15% of daily recommended intake of vitamins A, C, B1, potassium, calcium, and magnesium). In addition, snacks of sesame seed powder and spread (10 g each) at 57.6 kcal and 63.3 kcal, 2.1 g and 2.5 g carbohydrate, 1.6 g and 1.3 g protein, 5.5 g and 5.7 g lipid, respectively, with various vitamins and minerals provided to increase intake of calcium, polyunsaturated fatty acids, vitamin E, and phytochemicals.

Each week for 4 months, participants received 1 serving of each type of smoothie (4 types total) and a 5th serving of their choice (for a total of 5 servings per week) and 3 servings of the sesame seed snack. Compliance and consumption were recorded.


Investigators recruited 59 older adults, with 30 women and 12 men participating in the intervention and blood collection. One woman and 1 man refused to provide fecal samples after the 4-month intervention. Females were aged 77.7 + 7.6 years; males were aged 85.3 + 8.4 years. There were no significant differences in BMI (baseline=24.0 ± 2.8 kg/m2) or waist-to-hip ratio in females and males.

Compliance with smoothies and snack was 88.0% for females and 92.5% for males. Body weight increased significantly after 2 months (P=0.028), and then decreased to about 1 kg above baseline while BMI, waist and hip circumference, and waist-hip ratio did not change significantly.

Red blood cells (RBC), hematocrit, albumin, and BUN decreased significantly at 4 months; hemoglobin, cholesterol, and high-density lipoproteins (HDL) also increased significantly, but the change in low-density lipoprotein (LDL) cholesterol was not significant. Reduced glutathione (P<0.001), total sulfhydryl (P<0.015), protein bound sulfhydryl (P<0.019), and total antioxidant capacity (P<0.015) increased significantly over the 4 months. Oxidized glutathione (P<0.001) decreased significantly over the 4 months, while there was no significant change in thiobarbituric acid reactive substances.

Fecal SCFAs were unchanged at 4 months, as were the various SCFA contents. Bacterial species in the feces were significantly decreased at 2 and 4 months. The 4 dominant phyla were Firmicutes, Bacteroidetes, Proteobacteria, and Verrucomicrobia throughout the study, accounting for 95% of total bacterial count. Investigators identified 28 bacterial taxa at baseline, and at 2 and 4 months. The older adults had decreased Bacilli, Streptococcus, Ruminiclostridium, Deltaproteobacteria, Patescibacteria, and increased Lactobacillus after 2 and 4 months compared to baseline. At 2 months there were increased Bacteroidetes, and Bacteroides thetaiotaomicron, and at 4 months increased Agathobacter compared to baseline. A comparison of microbiota and total antioxidant capacity (TAC) found Ruminiclostridium_5, Agathobacter, Bacteroidetes, and Fusobacteriales negatively associated with TAC (P=0.003). Lactobacillus salivarius was positively associated with TAC (P=0.005). Sample sizes were determined to be adequate to detect interactions between gut bacteria composition and antioxidant enzymes.

Key Findings

Plant-based, antioxidant-rich snacks and smoothies can improve antioxidant capacity and alter gastrointestinal microbiota in older adults over 4 months when consumed on a regular basis.

Transparency: The authors do not disclose any conflicts of interest. Funding was through grants from the Ministry of Science and Technology, Taiwan.

Practice Implications

Diets high in vegetables, fruits, whole grains, and nuts have antioxidant, anti-inflammatory, and, thus, antiaging effects and reduce frailty.1,2 Higher intake of flavonoids in fruits and vegetables is associated with reduced subjective cognitive decline in older American adults.3 One of the unfortunate facts is that as adults age, their ability to chew, swallow, and digest decreases, an assumption made for this study population and, thus, a factor in the design of this study.4

Active phytochemical constituents with antioxidant properties are associated with food that is colorful: fruits, vegetables, nuts, and seeds.5 The question that clinicians would like answered is: Which fruits, vegetables, nuts, and seeds will cause the most effective, or the most problematic, shift in a patient’s microbiome if they have prediabetes, cognitive impairment risk factors, cancer risk factors, and so forth?6 Clinical questions are ahead of scientific answers in this regard.

Sesame seeds, Sesamum indicum, Pedaliaceae, are presumed to be native to sub-Sahara Africa and India, to be the first human oil-seed crop, and to have been domesticated more than 5,500 years ago as a drought-tolerant plant.7 Production in 2018 was more than 6 million tons. In 100 g or 3.5 ounces, there are 573 calories, 5% water, 23% carbohydrate including 12% dietary fiber, 50% fat, 18% protein, and 20% or more of the recommended daily requirement of several B vitamins, iron, magnesium, calcium, phosphorus, and zinc.7 Also present are phytic acid, a known binder of minerals that can reduce their absorption in the small intestine, and the lignans sesamolin, sesamin, pinoresinol, and lariciresinol.8 What gut bacteria sesame supports or reduces is largely unknown. Sesame is, unfortunately, a common allergen, ranked 9th among children and adults, and since November 2019 in Canada and the United States, it must be listed on the label if present in a food.9 Some 17% of children are allergic to sesame, with 20% to 30% presumed to outgrow this allergy.8

Sesame is, unfortunately, a common allergen, ranked 9th among children and adults, and since November 2019 in Canada and the United States, it must be listed on the label if present in a food."

This study of 4 months revealed that it was a reasonable length of time to assess for some biome changes. Very limited data were provided on the study subjects; for instance, I would like to have known how many were classified as healthy versus subhealthy adults and if there were outcome differences between the 2 groups. There was no indication if the snacks were taste-tested to make them palatable or attractive to the study subjects, a factor that could limit consumption. Similarly, there were no data on the selection of the 5th smoothie and whether this was based on taste, color, both, or neither. Neither were there details on the constituents of the 4 smoothies. Finally, the investigators described the foods as “texture modified,” but we do not know if that improved their ability to be chewed, swallowed, and digested, nor how the texture was modified, nor how well the subjects liked the smoothies and snacks. The study was generally well-written, but not all subheadings matched that section’s content.

Plant-based, antioxidant-rich smoothies including unknown vegetables, fruits, and nuts along with snacks prepared from sesame seeds can improve antioxidant capacity and alter gastrointestinal microbiota in older, presumably Taiwanese, adults over 4 months when consumed on a regular basis.

Categorized Under


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