Peter D. Leathwood

Aqueous extract of valerian root (Valeriana officinalis L.) improves sleep quality in man

The effect of an aqueous extract of valerian (Valeriana officinalis L.) root on subjectively rated sleep measures was studied on 128 people. Each person received 9 samples to test (3 containing placebo, 3 containing 400 mg valerian extract and 3 containing a proprietary over-the-counter valerian preparation). The samples, identified only by a code number, and presented in random order, were taken on non-consecutive nights. Valerian produced a significant decrease in subjectively evaluated sleep latency scores and a significant improvement in sleep quality: the latter was most notable among people who considered themselves poor or irregular sleepers, smokers, and people who thought they normally had long sleep latencies. Night awakenings, dream recall and somnolence the next morning were relatively unaffected by valerian. With the proprietary valerian-containing preparation, the only change was a significant increase in reports of feeling more sleepy than normal the next morning. Thus the questionnaire, simple to use and non-invasive, provides a sensitive means for detecting the effects of mild sedatives on different aspects of sleep in man. It also allows identification within the test population of the subgroups most affected.

Tryptophan Availability and Serotonin Synthesis

Under carefully chosen experimental conditions the consumption of specific diets or the administration of the precursor amino acid tryptophan (TRP) can influence serotonin (5-HT) synthesis. The mechanism proposed is as follows: The consumption of TRP and/or the proportions of carbohydrate and protein in a meal may change the plasma ratio of tryptophan to large neutral amino acids (TRP/LNAA), which in turn can influence the rate of TRP transport into brain, brain TRP levels and hence rates of 5-HT synthesis. It has been suggested that, via this mechanism, dietary interventions might influence a range of behaviours linked to serotoninergic neurotransmission. This short review examines some of the evidence for this idea, and concludes that when TRP is given, under some limited conditions, results are coherent with the idea that precursor availability can influence serotoninergic function. On the other hand, the suggestion that carbohydrate and protein meals can influence serotoninergic function is not supported by current evidence.

Breastfeeding and experience with variety early in weaning increase infants’ acceptance of new foods for up to two months ☆

BACKGROUND & AIMS Previous studies showed that (1) breastfeeding and (2) higher food variety early in weaning can increase acceptance of new foods for the next few days. Here we measure, in two European regions, effects of breast or formula feeding and experience with different levels of vegetable variety early in weaning on new food acceptance during two months following the start of weaning. METHODS Breast- or formula-fed infants received their first vegetable (carrot purée) and, over the next 9 days, either carrots every day; 3 vegetables changed every 3 days; or 3 vegetables changed daily. On the 12th and 23rd days they received new vegetable purées, zucchini-tomato then peas. Several weeks later, they received 2 more new foods, meat and fish. Acceptance of new foods was measured by quantities eaten and by liking ratings. RESULTS Breastfeeding and variety early in weaning increased new food acceptance. Frequency of change was more effective than number of vegetables fed. The combination of breastfeeding and high variety produced greatest new food intake. This effect persisted 2 months later. CONCLUSIONS These interventions correspond to differences in milk and vegetable feeding observed in the regions studied suggesting that the results have practical consequences for acceptance of new foods.

Effects of slow release carbohydrates in the form of bean flakes on the evolution of hunger and satiety in man

This study was undertaken to test the effects of plausible meals containing slow release starches in the form of bean flakes on plasma glucose and hunger in man. In a first study, volunteers consumed a hachis paramentier (shepherds pie) containing either bean purée or potato purée. After the meal containing potato, plasma glucose levels rose sharply, peaked at 30-45 min and fell below initial levels 2 to 3 h later. With bean purée there was a low, sustained increase in blood glucose. In a second study, volunteers consumed six hachis parmentier (three with bean purée, three with potato purée, topped with spinach, ratatouille or tomatoes). Relative to potato, the bean purée delayed the return of hunger and decreased ratings for propensity to eat a tasty snack.

Diet-induced mood changes in normal populations

Using an 11-item questionnaire and a double-blind experimental design, changes in mood, hunger and food preference after taking caffeine (100 mg), tryptophan (500 mg), tyrosine (500 mg) or placebo, were investigated in 60 volunteers. At the end of the study, volunteers also ranked the four treatments on a sedation/stimulation scale. Caffeine significantly increased scores for wakefulness, vigor, clarity of mind, energy, feeling full of ideas, feeling full of go and feeling efficient. Caffeine was also ranked as the most stimulating treatment (p less than 0.001). Tyrosine produced no changes, while tryptophan shifted mean scores towards somnolent and lethargic, and was ranked most sedating (p less than 0.05). None of the treatments changed hunger ratings or carbohydrate/protein preference.

Strategies of protein selection by weanling and adult rats.

Weanling and adult male rats were offered pairs of diets containing either 0 and 20%, 0 and 40%, 0 and 60%, or 10 and 40% casein. Initially they preferred the lower protein diets, and then after one to ten days abruptly switched to adequate levels of protein choice. After 14 days, the diets were changed so that the first group received 10 and 40%, the second 20 and 60%, the third 10 and 40%, and the fourth 0 and 60% casein. Following the change, all weanling rats showed significant and systematic shifts in percentage of total energy chosen as protein (%P-E); most adults did not. Within each group, the variability in %P-E selected between different rats was higher than the day-to-day variability of individuals. In the adults no significant correlations were observed between protein selection and brain serotonin metabolism. We conclude that protein intake in rats is regulated in the sense that all animals learnt to eat sufficient protein to maintain growth, and most animals ate a constant amount of protein each day. On the other hand, the range of protein intake between individuals, and the shifts in selection among the weanlings when diet choices were changed seem to preclude the existence of a mechanism which precisely regulates protein intake.

Quantifying the effects of mild sedatives

In quantifying the effects of mild sedatives both physiological and subjective aspects of sleep must be taken into account. A questionnaire analysis on a mild sedative (400 mg of an aqueous extract of Valeriana officinalis L.) showed that by subjective criteria it is sedative (i.e. it significantly decreased perceived sleep latencies and night awakenings, and improved sleep quality). In an EEG study on the same preparation the pattern of results tended to confirm the subjective evaluation (i.e. shorter mean sleep latency, increased mean latency to first awakening) but the changes did not reach statistical significance. The discussion critically examines some of the approaches used to test putative mild sedatives and suggests a rational approach to analysing their effects.

Effect of different regimens of early malnutrition on behavioural development and adult avoidance learning in Swiss white mice

1. The effects of perinatal malnutrition on behavioural development and adult shuttle-box avoidance performance were studied in Swiss white mice. 2. Mice were malnourished (a) from the 7th day of gestation until birth, (b) from birth until weaning, or (c) during both gestation and the sucking period. 3. Pups born of protein-restricted mothers had reduced birth weights, retarded development and poor adult avoidance performance, even if reared from birth by well-nourished mothers. 4. Postnatal malnutrition, induced either by restricting maternal diet or by rearing in large litters, retarded development during the second half of lactation and lowered subsequent adult avoidance performance.

Phosphatidyl choline and avoidance performance in 17 month-old SEC/1ReJ mice

Male SEC/1ReJ mice aged 6 or 17 months were fed diets containing 0, 2, 4, and 8% added phosphatidyl choline. After 4 days on the test diets they were given 5 daily sessions of 100 trials each in the shuttle-box. The younger mice rapidly acquired an avoidance response and reached high, stable levels of performance. The older mice learned more slowly and reached significantly lower performance levels (p less than 0.01). Phosphatidyl choline had no effect on performance of young mice, while in the older mice the highest dose level of phosphatidyl choline increased avoidance performance by nearly 30% (p less than 0.05).

The Lasting Influences of Early Food-Related Variety Experience: A Longitudinal Study of Vegetable Acceptance from 5 Months to 6 Years in Two Populations.

Children’s vegetable consumption falls below current recommendations, highlighting the need to identify strategies that can successfully promote better acceptance of vegetables. Recently, experimental studies have reported promising interventions that increase acceptance of vegetables. The first, offering infants a high variety of vegetables at weaning, increased acceptance of new foods, including vegetables. The second, offering an initially disliked vegetable at 8 subsequent meals markedly increased acceptance for that vegetable. So far, these effects have been shown to persist for at least several weeks. We now present follow-up data at 15 months, 3 and 6 years obtained through questionnaire (15 mo, 3y) and experimental (6y) approaches. At 15 months, participants who had been breast-fed were reported as eating and liking more vegetables than those who had been formula-fed. The initially disliked vegetable that became accepted after repeated exposure was still liked and eaten by 79% of the children. At 3 years, the initially disliked vegetable was still liked and eaten by 73% of the children. At 6 years, observations in an experimental setting showed that children who had been breast-fed and children who had experienced high vegetable variety at the start of weaning ate more of new vegetables and liked them more. They were also more willing to taste vegetables than formula-fed children or the no or low variety groups. The initially disliked vegetable was still liked by 57% of children. This follow-up study suggests that experience with chemosensory variety in the context of breastfeeding or at the onset of complementary feeding can influence chemosensory preferences for vegetables into childhood.