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.