C ARBOHYDRATES AND M OOD IN H EALTHY A DULTS

13.4.1 C ARBOHYDRATES AND M OOD IN H EALTHY A DULTS

The studies that have investigated the effect of carbohydrates on mood in healthy adults are summarized in Table 13.3. From this table you can see that some studies have focused on the effect of carbohydrate consumption in the morning, some have focused on both morning and afternoon, and some have limited their attention to the afternoon. If attention is focused on effects of carbohydrate consumption in the morning, most of the studies 120–125 indicate a positive effect, including a lowering of

Dietar

TABLE 13.3

Summary of Studies Investigating the Effect of Carbohydrates on Mood

y Carboh

Study Participants Meal Type and Time Given

Outcome Measures

Time of Assessment

Outcome Affected

ydrates as Mood and P Fischer et al.,

Effect of Consuming Carbohydrates in the Morning

Before and hourly for 3 h after No effect of meals on ratings of any 2002

Male

CHO rich vs. balanced vs.

Rating 20 mood states on 7-point

mood Fischer et al.,

students

protein rich at 7 A . M .

bipolar scales

breakfast

Lower POMS depression scale 2001

Male

CHO vs. protein vs. fat at 7 A . M . Ratings of mood states on 7-point

Before and hourly for 3 h after

score after CHO vs. protein Benton et al.,

students

bipolar scales, POMS

breakfast

More confused and anxious after 2001

Female

Fast vs. high vs. low CHO at 10 Analogue-scale assessment of six

Before, 15 min, and 1 h after

adults

A . M ., each crossed with CHO

mood states

breakfast and 15 min and 1 h after high CHO; snack improved mood

only in high-CHO condition Lloyd et al.,

snack or no snack at 11:30

snack

Decline in fatigue after low-fat er 1996

Mostly

Low, medium, and high fat

Ratings of 16 different mood

Before and at 30, 90, and 150 min

female

high-CHO breakfast formance Modulators adults

crossed with low, medium and

states on 100-mm line

after breakfast

high CHO and no breakfast

Reid and Male and

Increase in energy 30 min after Hammersley,

Sugar or saccharin-sweetened

POMS

At 9 A . M . before consuming

consuming the sugar beverage 1995

female

orange beverage or water

beverage and 30 and 60 min after

adults Smith et al.,

Less content, interested, sociable, 1994

Male and

High-CHO, high-protein or no

Introversion–extroversion,

Before 8 A . M . or 8:30 breakfast

and 1.5 and 2.5 h after breakfast and outgoing after CHO and no students

female

breakfast

anxiety, levels of psychiatric

breakfast vs. protein Wells et al.,

symptoms

Less dreamy and sleepy 30 min 1998

Male and

Gastric infusion of sucrose,

POMS, SSS, VAS, UWIST

Before and at half-hour intervals

female

lipid, or saline

after 10:15 A . M . gastric infusion after sucrose, but more sleepy 2 h after sucrose and less dreamy after sucrose at 3.5 h

TABLE 13.3 (continued)

Summary of Studies Investigating the Effect of Carbohydrates on Mood

Study Participants Meal Type and Time Given

Outcome Measures

Time of Assessment

Outcome Affected

Consumption of Carbohydrates in the Morning and Afternoon

Spring et al., Male and

Overall, females sleepier after 1983

High CHO or high protein

POMS, SSS, analogue ratings of

2 h after eating breakfast at 7:15

female

to 8:30 A . M . and 2 h after eating CHO meal; people 40 and older are adults

mood

lunch at 11 A . M . and 1 P . M .

less tense and calmer after CHO breakfast; males are calmer after

CHO meal Deijen et al.,

10:30 A . M . and 6 P . M . 1.5 to 2 h Diet group had higher anger in the 1989

Primarily

High-protein food until 1:30

POMS

morning college

female

P . M . and high-CHO food after

after meal and after being on the

1:30 P . M . or ad libtum diet

diet for 3 weeks

students Thayer, 1987

Primarily

Morning snack increased energy, females

Sugar snack vs. exercise

AD/ACL

1 h after abstaining from food and

at a time that was convenient to but afternoon snack increased and

them

then decreased energy; snack increased tension

Functional F

Effect of Consuming Carbohydrates at Lunch or in the Afternoon

Markus et al., High- and

Stress increased depression in 2000

CHO rich vs. protein rich at 11

POMS

1.5 h after lunch and before and

low-stress-

high-stress group after protein-rich ood Carboh prone

A . M . or noon

after stress induction

but not CHO-rich meal students Markus et al.,

Stress increased depression and 1998

High- and

CHO rich vs. protein rich at 11

POMS

1.5 h after lunch and before and

low-stress-

decreased vigor in low-stress group prone

A . M . or 1 P . M .

after stress induction

on both diets, but only on protein- ydrates students

rich diet in high-stress group

Dietar Wells et al.,

2.5 h after high-CHO lunch 1995

Male adults High fat, low CHO or low fat, Ratings of alertness, cheerfulness,

Hourly starting at 9 A . M ., with

high CHO, both with moderate

and calmness

lunch given at 12:45 P . M .

alertness greater vs. high-fat, low-

CHO condition y Carboh Reid and

protein

Ratings of 10 mood states using Immediately after and 60 and 120 Sucrose group felt more fatigue at Hammersley,

Male and

Saccharin, sucrose, maize oil,

120 min and was calmer at 60 min 1999

female

or sucrose and maize oil added

visual analogue scales

min after eating yogurt at 11

than saccharin group ydrates as Mood and P Lloyd et al.,

adults

to yogurt at 11 A . M .

Less drowsy, uncertain, and 1994

Mostly

Low fat, high CHO; medium

Visual analogue ratings of 16

30 min before and 30, 90, and 150

females

fat, medium CHO; and high fat,

mood states

min after 12:30 P . M . lunch

muddled after medium-fat and -

CHO lunch, but less tense after low-fat, high-CHO lunch Christensen and

low CHO

No effect on mood Redig, 1993

Female

Sugar rich, starch rich, or

SSS, POMS, AD-ACL

Before and at 30, 60, 90, 120, and

college

protein rich at 1 P.M.

180 min after 1 P . M . lunch

students er Pivonka and

Greater sleepiness after sugar Grunewald,

Female

Sugar or aspartame Kool-Aid SSS, visual analogue ratings of 32

Before and 1 h after consuming

Kool-Aid formance Modulators

college

or water at 3:30 P.M.

adjectives and POMS

beverage at 3:30 P . M .

1990 students Smith et al.,

No effect on mood 1988

Male and

High-protein, high-starch, or

Visual analogue ratings of 18

Before and 1.25 h after lunch

female

high-sugar lunch

adjectives

adults Spring et al.,

Before and 4 times after lunch Fatigue greater 2 h after CHO than 1986

Female

CHO-rich, protein-rich,

SSS, POMS, visual analogue

after no lunch Spring et al.,

adults

balanced, or no lunch

ratings

No effect on mood 1986

Male adults

Starch or protein lunch

SSS, POMS

Before and hourly for 5 h after

noon lunch

Note : POMS = Profile of Mood States; SSS = Stanford Sleepiness Scale; VAS = Visual Analogue Scales; UWIST = Mood Adjective Checklist; AD-ACL = Activation/Deactivation Adjective Check List.

Functional Food Carbohydrates

depression, a decline in fatigue, an increase in energy, less dreamy and sleepy 30 min and 3.5 h after carbohydrate consumption, but sleepier at 2 h after carbohydrate consumption, and a decline in tension and an increase in calmness in people over

40 years of age. However, at least one study 126 found no effect of a carbohydrate breakfast when compared with a protein and balanced breakfast. Two studies 127,128 found primarily negative effects, indicating that a carbohydrate load in the morning decreased feelings of contentedness, interest, sociability, and outgoingness, but con- fusion and anxiety also decreased. However, some of these effects declined with a carbohydrate snack.

These contradictory findings may be due to the discrepancy in the procedures followed in the various studies. A review of Table 13.3 reveals that the meal com-

parisons ranged from comparing carbohydrate, protein, and balanced meals, some- times including a fast, to various combinations of carbohydrates and fats, to gastric infusion of single macronutrients. Similarly, the type of outcome measures varied from using standardized mood assessment measures to analogue ratings, and the time of consumption of the selected foods and assessment of outcome measures varied considerably. When these study variations are considered, it is perhaps under- standable that there are variations in the outcome of these studies. In spite of these variations, the majority of the studies suggest that a carbohydrate load consumed in the morning has a beneficial effect on mood, and the beneficial effect seems to be one of improved energy or decreased fatigue and a general improvement in mood. Because most studies indicate a positive mood-altering effect from consumption of

a carbohydrate load in the morning, it seems safe to conclude that such a positive effect will occur in most individuals. However, this positive effect should not be promoted as a definite outcome of morning carbohydrate consumption, as some individuals will obviously not feel such an effect, and some may have a negative reaction. Additionally, it is difficult to identify the time in which the effect will occur, as the studies varied not only the time of morning in which carbohydrates were administered, but also the amount of time that elapsed before testing the effect of the carbohydrate.

Table 13.3 also summarizes the results of studies assessing the effect of con- suming carbohydrates at lunch or in the afternoon. In reviewing these studies, it is again apparent that there is considerable variation in terms of the macronutrients varied, the time in which the macronutrients were consumed, and the time of assessment of mood following consumption of the different macronutrients. In spite of these variations, there seem to be some consistencies emerging. When either a carbohydrate-rich meal or sucrose is compared to a condition in which no macro- nutrient is consumed (no lunch, water, saccharin), the participants consuming the sucrose or carbohydrate-rich meal report being sleepier or more fatigued. 129–131 However, if the effect of a carbohydrate-rich meal is compared with that of a protein- rich meal, there seems to be no significant difference between them on mood. 132–134 There is also little effect on mood if the research participants consume a high-protein meal in the morning and a high-carbohydrate meal in the afternoon for an extended period of time, such as 3 weeks. 135 However, this failure to find an effect of a carbohydrate-rich vs. a protein-rich meal may be due to the heterogeneous nature of the research participants, as it has also been demonstrated that high- and low-

Dietary Carbohydrates as Mood and Performance Modulators

stress-prone individuals respond differently to these two meals when stressed. Two studies 136,137 have demonstrated that only low-stress-prone research participants experienced a rise in depression following a stressful task when consuming a car- bohydrate-rich meal. The carbohydrate-rich lunch protected the high-stress-prone participants from experiencing a similar rise in depression.

Several studies have also compared the effect of varying the carbohydrate and fat contents of a meal. In one of these studies, 138 the medium-fat and medium- carbohydrate lunch had the positive effects of less drowsiness, uncertainty, and muddledness, and in the other study, 139 it was the low-fat and high-carbohydrate meal that created the positive effect of greater alertness. However, in both studies, the meal that had the positive effect was the meal type that was most comparable to the participants’ typical meal. Therefore, it may be that any deviation from a person’s typical meal pattern has a negative effect.

These studies seem to suggest that a carbohydrate-rich lunch will increase feelings of sleepiness and fatigue compared to not eating lunch. However, there is no difference when comparing a protein- vs. carbohydrate-rich lunch, so it may be the consumption of any lunch that makes the primary difference. This effect may

be particularly noticeable if the lunch deviates from what is typically consumed.