Health Benefits Of Blueberry Juice

Published Date: 02 Nov 2017

Semester 2

Special Studies Essay 2 Cover Page

Health Benefits of Blueberry Juice

Ammad Chaudhry

UB No. 12002974

Date of submission: 12/02/2013

Word Count: 1655

Special Studies Supervisor - Dr.Sheldrake

Clinical Sciences Foundation Year

This submission is part of a summative assessment.

Introduction

Blueberries, fruits_from the Vaccinium plant, are emerging as a dietary source of more than 20 anthocyanins [1] ,_antioxidants, flavonols, multi-vitamin_macronutrients, and_dietary fibre (table 1 [2] ). Multiple_pre-clinical_animal studies have concluded thatthese compounds may_hold_benefits_such_as_improving cognitive_function [3] and juice_extract_increased AMPK_phosphorylation_and glucose_uptake in both_muscle_and_adipocytes and_also inhibited adipogenesis [4] .

Clinical_studies in humans_with_diabetes and hypertension_have yielded noticeable reduction_in risk_of_Cardiovascular_Disease (CVD), more so in the reduced_levels_of glucose, _lipids_and_systolic blood_pressure [5] .

Blueberry_Juice (BBJ) is_a_preferred_form of_consumption_however_anthocyaninlevels in processed_BBJ are_significantly less_than_fresh whole_blueberries. While_BBJ yield was_83%, only_32% of the_anthocyanins_were_recovered in_single-strength_BBJ [6] .

Blueberry Juice and its association with glucose regulation

Antioxidant_polyphenols _BBJ may be involved in inhibition_of carbohydrate_digestion and the_absorption_of its constituent sugars_these polyphenols_have been_observed_to inhibit_α-amylase_and_α-glucosidase_enzyme_activities_in_vitro [7] and may also_stimulate more_insulin_secretion and the sensitivity_of_insulin_receptors which would_significantly improve_glucose_uptake in body_tissues (Figure 17).

One_route of_intestinal uptake_of_glucose is_done through_active_transport_by Na+-Glucose_symporter_SGLT1 [8] , [9] .Two_Na+ _ions_bind to_SGLT1_and_produce_a conformational_change to allow_Na+ and_glucose_to enter_the cell. Polyphenols_found in_BBJ_studied were_found_to influence_on glucose_transport_by_inhibiting_SGLT1 transporter_in_vitro [10] , [11] , [12] .

Table : Berries with select nutrient and phytochemical profiles expressed in values per 100 g of edible portion.

NF= Not found in database

Fruit

Total Anthocyanidin content (mg)*

Total flavan-3-ols (mg)

Total flavonols (mg)

Calories (kcal)

Fibre (g)

Vitamin C (mg)

Vitamin E (mg)

Blackberry

90.46

42.5

2.49

43

5.3

21

1.17

Blueberry

163.52

51.71

9.72

57

2.4

9.7

0.57

Bilberry

430.91

4.13

NF

NF

NF

NF

NF

Chokeberry, raw

437.22

NF

8.90

NF

NF

NF

NF

Cranberry juice (unsweetened)

NF

0.92

20.82

46

0.1

9.3

1.20

Currant, Black, raw

272.44

1.17

12.69

63

NF

181

1.0

Mulberries, raw

NF

NF

2.47

43

1.7

36.4

0.87

Black raspberry

324.02

NF

NF

NF

NF

NF

NF

Red raspberry

38.68

6.63

1.32

52

6.5

26.2

0.87

Strawberry

33.63

4.51

1.6

32

2.0

58.5

0.29

Anthocyanins in Blueberries with relation to triglyceride regulation

Trials_in mice_fed_with_purified_anthocyanins_responded_with lowered_triglyceride and cholesterol_levels_in serum [13] . Noticeably, the_mice_on a high fat diet fed with_anthocyanins_displayed_changes in many_obesity_parameters such_as_leptin levels_and_enhanced_β-cell_function. BBJ_however, did_not_change these_parameters expect_for increasing_leptin levels. Leptin_is a_hormone_produced_by_adipocytes [14] 15, which_reduces_triglycerides_formation_in_various_organs_by_increasing_free_fatty_acid (FFA) _oxidation_and_decreasing_its_esterification_to_triglycerides [16] .

C:\Users\User\Desktop\ijms-11-01365f1.jpgFigure : Potential sites of action of dietary polyphenols on carbohydrate metabolism and glucose homeostasis.

Protection against Diabetes

Anthocyanins_have_been_linked_with_their_ability_to_protect_from_diabetes [17] ,_ [18] _in animals [19] . Clinical_evidence_is_scare_however_there_have_been_many_pre-clinical trials_with_diet-induced_diabetes, mirroring type 2 diabetes.

Anthocyanin_compounds_must_be_bioavailable_(absorbed_from_Gastro-Intestinal-Tract) to be_pharmacologically_effective in vivo. Oral_consumption of_anthocyanins has increased_levels in_serum [20] , [21] however_the_uptake_of the_anthocyanins_was_very_low (<1%_of_dose) [22] , [23] _however_when_formulated_with_Labrasol, _this_hypoglycaemic activity_was_comparable_to_the_anti-diabetic_drug_Metformin [24] .

Memory Improvements and Brain Function

Pre-clinical_evidence_indicates_blueberry_supplementation_enhances_memory_and motor_performance in_aged_animals [25] , [26] . These_observations_have_been_accredited to anthocyanins [27] , [28] and_have_been_identified_in_specific_brain_regions, including hippocampus_and_neocortex [29] , essential_for_cognitive_function [30] .

There_is_supporting_data_that_anthocyanins_can_enhance_glucose_disposal through a number_of_mechanisms [31] , [32] . This_may contribute to_improved_neuro-cognition as glucose_disposal_and correction_of_hyper-insulinemia_would mean_greater_clearance of_central β-amyloid_as_well as_enhanced_signalling_in_memory_centres [33] .

Protection against Cardiovascular Disease (CVD)

Anthocyanins_lowered risk of CVD_related deaths_among_1,950_men in the_highest category_of berry_intake (>408 g/day) versus_men with the_lowest intake (<133 g/day) during a_mean follow-up of_12.8 years [34] which_showed_a_decrease_in_LDL_oxidation, a_decrease in_cholesterol, and_an_increase_in_HDL_following_berry_intake [35] , [36] .

9_out of_20 trials_reviewed showed_a significant_decrease in berry_postprandial oxidative_stress_and lipid_peroxidation [37] , [38] , these_are_involved_in the_development of_atherosclerosis [39] , [40] .The_principal mechanisms_underlying the potential cardio-protective_effects of_berries_include_counteracting_free_radicals_with_anti-oxidants, and up-regulating_endothelial_nitric oxide synthase_expression to_reduce_inflammation. Consequently_development_of_atherosclerosis is_slowed and normal_vascular_function is_preserved.

Risks of drinking BBJ and its reaction with Cytochrome P450 (CYP)

CYP_enzymes_breakdown_endogenous_components_and_xenobiotics [41] , such_as drugs (CYP3A4_and_CYP2C9_is_involved_in_the_metabolism_of_>76%_of_clinical_drugs) into_metabolites.

Polyphenols_are_present in_various_fruits and_as_phytochemicals, human_polyphenol intake_is_~1 g/day_in_Western_societies [42] and_polyphenols’_reaction_with_drugs have recently_come into_focus [43] as_interactions_have_resulted in_inhibiting CYP_P450 enzymes.

A_study of_inhibitory_effects of_60_dietary_polyphenols, including_chalcones, _flavonols, and_flavan-3-ols, _on_CYP3A4_and_CYP2C9_was_performed_which_found_that_non-polyphenolic_compounds, _anthocyanins_and_flavonoids_showed_negligible_inhibition of_CYP_enzymes. BBJ_consumption_did_not_affect_pharmacokinetic_parameters associated_with_drug_metabolism_in_healthy_volunteers [44] .

Conclusion

BBJ_is_attractive_for improving_health, however, during_processing_BBJ_loses_many of its_nutritional_values6,_consumption_of fresh_or_frozen_whole_berries_low_insugar as_part_of a_regular_diet_is_recommended.

Positive_effects_of_polyphenols_on_glucose_homeostasis_have_been_obtained_in_vitro and_in_pre-clinical_studies, _but_definitive_conclusions, _especially_from_controlled human_studies_have_not_been_obtained. There_is a_scarcity_of_human_studies_with clinically_relevant_end-points_indicating_effects_during_postprandial_control_of_dietary carbohydrates, _pancreatic_insulin_secretion_and its_functions_on glucosehomeostasis.

Evidence_on_the_potential_of_polyphenolic_compounds_to_hinder_carbohydrate_digest-on,absorption_and_to_suppress_hyperglycaemia_in_the_postprandial_state_is promising. _However, _it_is mostly_based_on simple_in_vitro_and animal_studies. Current_evidence_from human_studies_suggests_that_blueberries_may_improve_short-term_glycaemic_control.

One_important_issue_in_research_on_dietary_phytochemicals_is_the_lackof knowledge on_their_absorption,metabolite_composition_and_tissue_distribution. Plants contain thousands_of_metabolites_in_different_combinations, and_the_identification_of_active molecules_in_a_given_metabolic_pathway_is_an_extremely_challenging_task. Further comparative_human_intervention_studies_should_address_the_effects_of_whole berries versus_purified_berry_anthocyanin’s, such_studies_are_readily_conceived but expensive and_challenging_to_conduct.

BBJ’s_interaction_with_CYP_P450_enzymes_was_found_to_be_negligible_in_human trials,however_a_larger_variety_of_trials_are_required_to_safely_conclude_this.