Re: Clinical Trial Indicates that Seaweed Extract May Improve Human Postprandial Cognitive Function

PDF (Download) Kelp (Rockweed; Ascophyllum nodosum, Fucaceae) Bladder Wrack (Fucus vesiculosus, Fucaceae) Cognitive Function Date: 02-28-2018 HC# 021861-587 Haskell-Ramsay CF, Jackson PA, Dodd FL, et al. Acute post-prandial cognitive effects of brown seaweed extract in humans. Nutrients. January 2018;10(1):85. doi: 10.3390/nu10010085. The regulation of glucose absorption in the body is important to overall health, including cognitive functioning. Dips or spikes in glucose levels can adversely affect cognitive function, and studies indicate that foods that release glucose slowly into the system—those with a low glycemic index (GI)—have a beneficial effect on cognition. While adhering to a low-GI diet will help to regulate plasma glucose levels, it can restrict the types and amounts of food one can eat. An alternative to a low-GI diet is to slow the absorption of glucose into plasma by limiting the breakdown of carbohydrates in the body. Research finds that polyphenols do this by inhibiting the enzymatic function of α-amylase and α-glucosidase; they also increase blood flow to the brain. In vitro studies on polyphenol-rich kelp (rockweed; Ascophyllum nodosum, Fucaceae) and bladder wrack (Fucus vesiculosus, Fucaceae), both brown algae, show they inhibit α-glucosidase in vitro to a greater extent than the prescription antidiabetic drug acarbose; both are rich in phlorotannins, which are found almost exclusively in brown algae. A previous controlled human trial has reported that a brown seaweed supplement increased insulin sensitivity and appears to have fewer adverse effects than acarbose. However, research in animals and humans is quite limited. This randomized, placebo-controlled, double-blind, parallel-group clinical trial aimed to assess the impact of brown seaweed extract on postprandial cognitive function. The study was conducted at the Brain, Performance and Nutrition Research Centre, Northumbria University; Newcastle upon Tyne, United Kingdom. Healthy subjects between the ages of 18 and 65 were recruited. Only subjects who reported post-meal drowsiness were included, as they were considered more likely to be able to show significant improvement in postprandial cognitive performance. Exclusion criteria included pre-existing medical conditions, prescription medication or herbal supplement usage, learning or cognitive difficulties or history of head trauma, smoking, excessive caffeine consumption, pregnancy or lactation, and other specified concerns. Subjects participated in one 6-hour session in which they received either a 500-mg extract of rockweed and bladder wrack seaweeds, equivalent to 10 g of dried seaweed (InSea2®; innoVactiv Inc.; Rimouski, Quebec, Canada), or a placebo of hypromellose with titanium dioxide as an opacifier (see Table 1 in article for composition data). InSea2 has a polyphenol content >20%. The treatments were identical in appearance, and an individual dose was administered as 2 tablets in a sealed foil packet. Treatments were prepared by innoVactiv and randomized by an independent third party. Cognitive and mood measures were administered with the Computerised Mental Performance Assessment System (COMPASS; Northumbria University) via laptop computer and included the following assessments: word presentation/immediate word recall; simple reaction time (SRT); digit vigilance; and choice reaction time (CRT). Visual analog scales (VAS) were used for subjective assessments of concentration, stamina, tiredness, hunger, thirst, and fullness. The study session began after a 12-hour overnight water-only fast. Subjects completed an initial baseline assessment, which included 1 round of word recall, SRT, digit vigilance, CRT, and VAS. At this point, subjects took their treatment and had a 30-minute break before consuming a lunch of 4 sweet waffles with 2 tablespoons of maple syrup and 250 mL of water. After having 20 minutes to complete the meal, subjects immediately took their first postprandial assessment. This consisted of 1 repetition of word recall, followed by 3 repetitions of the SRT, digit vigilance, and CRT, and ending with 1 repetition of VAS. This block of assessments took ~30 minutes and was repeated at 40, 80, 120, and 160 minutes post-lunch, with ~10-minute breaks between assessments. It was structured to be mentally demanding and fatiguing. Blind analysis was completed by independent t-tests, Pearson's chi-square, and linear mixed models controlling for baseline. Sixty adults (33 females and 27 males) were recruited for the study. Of the 60 subjects who completed the study, data for 59 were analyzed; 1 subject in the placebo group produced consistent outliers indicating non-engagement in the tasks. At baseline, those who were to be in the brown seaweed group were significantly better at the digit vigilance task (P=0.046). In the digit vigilance assessments, subjects receiving brown seaweed extract were significantly more accurate during the first of 3 repetitions in each assessment (P=0.039), although their performance declined faster. By the third repetition, their performance was equal to that of the placebo group. Raw counts of false alarms in the digit vigilance test were not significantly different in the 2 groups, but a threshold analysis found significantly higher false alarm rates in the placebo group at threshold rates of 5, 6, and 7 (P=0.02, 0.05, and 0.02, respectively). [Note: This was a post hoc analysis done in response to observed variation among subjects and groups in the number of false alarms.] In the CRT assessment, there was no significant difference between the 2 groups, but there was a significant decline in performance only in the placebo group at the 120-minute and 160-minute assessments (P=0.001 and 0.020, respectively). There was no significant difference between groups for the word recall, SRT, or VAS assessments. In the researchers' opinion, this study indicates brown seaweed extract may be useful to improve postprandial cognitive function. They note that the total effect of brown seaweed extract on cognitive function may not have been captured in the 190-minute assessment period, since another study found that phlorotannins in brown seaweed are metabolized as much as 8 hours after ingestion, meaning their cognitive effects may not have been realized within the testing period. Additionally, future research could look at other assessment structures, since the repeated block style used in this study may have led to subject disengagement rather than fatigue. Brown seaweed could provide a high-polyphenol (phlorotannin) and low-GI dietary supplement for general carbohydrate regulation and cognitive function. The study was funded by innoVactiv Inc., the manufacturer of InSea2, and one of the authors (Bérubé) is employed by innoVactiv.