How to Become Smarter (9 page)

One study investigated the effects of erythrosine, a cherry-pink synthetic food coloring, on the behavior of rats [
69
]. Erythrosine affects metabolism of brain chemicals called neurotransmitters, which regulate attention, motivation, and activity level among other things. The study showed that erythrosine had no detectable effect on behavior of the rats at the (low) doses comparable to human intake of this dye with food. High doses of erythrosine did produce changes in the behavior of the rats. These changes resembled the effects of drugs that exacerbate symptoms of attention deficit hyperactivity disorder. The authors concluded that erythrosine may affect metabolism of several neurotransmitters in the brain. Another conclusion was that relevant (low) doses of erythrosine have no detectable effect on the activity level or other components of behavior relevant to ADHD.

Other studies investigated the effects of iron, which food companies often add to breakfast cereals or bread in order to “fortify” them. To be precise, iron is not a food additive but a nutritional supplement. In one experiment scientists injected adult rats daily with 2.5 mg/kg and higher doses of iron. The scientists then subjected the rats to a battery of tests assessing learning and memory [
70
]. All doses showed impaired learning starting on day 3 of the experiment. The lowest dose in this study exceeded the recommended daily allowance of iron by about 10-fold. It is unclear whether the results of the experiment are applicable to food products fortified with small amounts of iron. Note that a finding of an adverse effect at a large dose does not necessarily mean that a lower dose will have a similar effect of smaller magnitude. In biological systems, a smaller dose can have no effect at all, or it may have a different, even beneficial effect [
71
,
72
]. Two other studies on rats investigated the effects of large doses of iron, about 40 times the recommended daily allowance for humans. The results showed that iron can impair some components of memory function, such as novel object recognition [
73
,
74
].

Leucine is an amino acid used by the food industry as a flavor enhancer. Bodybuilders use it as a food supplement. One study showed that injection of large amounts of leucine can impair learning in young rats [
75
]. This negative effect is unlikely to be relevant to the amounts of leucine that can be present in food. Yet this effect is relevant to some bodybuilders who gorge on leucine.

Magnesium sulfate is an acidity regulator and firming agent. The food industry also uses it as a coagulant to make tofu cheese. Large amounts of magnesium sulfate can act as a laxative and may cause diarrhea, and can also temporarily impair attention and working memory in humans [
76
]. A study on rats showed that large doses can impair learning [
77
]. These findings are unlikely to be relevant to the small amounts of this substance present in human food. As mentioned above, a finding of an adverse effect at a large dose does not necessarily mean that a lower dose will have a similar negative effect of smaller magnitude. The lower dose may have no effect or a different kind of effect. The readers who are interested in unusual effects of low doses can do some research on the term “hormesis” [
71
,
72
].

Monosodium glutamate (MSG) is a flavor enhancer used by the food industry. Research shows that large doses of MSG (2,000 to 4,000 mg/kg) reduce activity level in mice [
78
] and can impair learning in young rats [
79
,
80
]. These findings may not be relevant to the small amounts of MSG (well below 100 mg/kg) that humans can ingest with food.

To meat products the food industry often adds nitrates, such as sodium nitrate or potassium nitrate, as preservatives and color fixatives. Large doses of nitrates, which can serve as a treatment for angina pectoris, can cause headaches in susceptible people [
81
]. This observation is not in the category of effects on mental state, but it is worth mentioning. This negative effect may not be applicable to the small doses of nitrates present in food products. Sodium
nitrite
is a related food additive that the food industry uses as a preservative and color fixative. A large dose of sodium nitrite (55 mg/kg), which is unattainable with the amounts present in human food, can reduce activity level of rats [
82
]. A smaller dose of this substance (11 mg/kg) can impair learning in rabbits [
83
]. The latter dose is achievable in humans with daily consumption of large amounts of processed meats. Propionic acid is another preservative, and large doses of this substance impair mental performance in rats [
84
]. This negative effect may not be applicable to the doses normally present in food products.

Propylene glycol is a humectant and a solvent for other food additives and drugs. One clinical case report described a patient who had a history of recurrent treatment-resistant epileptic seizures [
85
]. After analyzing the blood work and other laboratory data, the authors concluded that the seizures were the result of propylene glycol poisoning from the patient’s favorite fruit drink. After the patient stopped consuming the suspected fruit drink, seizures never occurred again. This single observation in no way constitutes rigorous proof that small amounts of propylene glycol can cause seizures. The above patient most likely consumed excessive amounts of this substance, enough to change the concentration of total protein in blood. The authors stated that the shift in blood protein concentration in all likelihood was the main cause of seizures. There is an additional possible explanation. One study shows that propylene glycol can enhance the release of a brain chemical called dopamine from neurons [
86
]. At high doses, dopamine-releasing drugs such as amphetamine can cause seizures [
87
]. Thus, increased release of dopamine in the brain of that patient could also be responsible for the seizures.

Stannous chloride is a color retention agent and antioxidant. Large doses of this chemical can either stimulate or depress the central nervous system in laboratory animals, depending on the context [
88
]. It is unknown if the small doses of stannous chloride present in human food can have any psychotropic effects on humans.

Refined sugar (sucrose) is a famous and controversial food additive. Early studies suggested that consumption of sucrose can contribute to “inappropriate behavior” in children [
89
,
90
]. Some other studies even suggested that elimination of refined sugar from the diet of prisoners (replacement with fruit) can improve their behavior [
91
]. On the other hand, later studies showed that ingestion of large amounts of sucrose has no effect on the behavior of children and convicts [
89
,
92
,
93
].

Nevertheless, the role of refined sugar in the current epidemic of obesity is widely accepted and the scientific evidence is compelling. Experiments on laboratory animals show that sucrose can cause weight gain, increase the blood cholesterol level, and negatively affect learning and memory [
94
,
95
]. For example, one study on rats shows that consumption of a sucrose solution can increase distractibility and impair the ability to get accustomed to repeated stimuli [
96
]. Another study shows that obesity-causing doses of sucrose can impair learning in rats [
95
]. One report shows that, in humans, a sucrose solution can cause sleepiness 30 to 60 minutes after ingestion without any other noticeable effects on mental abilities [
97
]. Another study on humans shows that a single dose of refined sugar has no effect on mood or attention but can improve some components of memory [
98
]. This beneficial effect disappears with repeated administration of sucrose. A recent review of high-quality studies concluded that refined sugar is unlikely to play a role in inappropriate or delinquent behavior of children [
89
]. Based on the available literature, we can conclude that the negative effects of sucrose for the most part affect physical health and the effects on mental abilities are small.

Table salt (sodium chloride) is another familiar food additive. To the best of my knowledge, there is no evidence that it has any detrimental effects on mental performance. Many of the diets described in this book allow adding small amounts of salt for taste. Nonetheless, salt has adverse effects on the cardiovascular system and studies suggest that cutting consumption of salt by half can reduce incidence of cardiovascular disease in the population.

Dietary supplements that consist of micronutrients such as vitamins and minerals are a special category of artificial ingredients that differs from food additives. The food industry adds food additives to food and this carries negative connotations in the minds of consumers: “MSG causes you to overeat,” or “sugar-sweetened soft drinks contribute to obesity.” In contrast, the vendors of dietary supplements sell them separately from food and advertise them as something that can improve your health and well-being. In the United States, there is a lot of misleading advertising associated with dietary supplements. They are not prescription drugs and the Food and Drug Administration does not regulate them as strictly. Regardless of the advertised beneficial effects on health, all dietary supplements must carry a disclaimer on the package that “This product is not intended to diagnose, treat, cure or prevent any disease.” On the QuackWatch website, readers can find an excellent overview of the deceptive tactics often employed by the vendors of dietary supplements.

Vitamins and minerals (micronutrients) are naturally present in sufficient amounts in many healthy types of food such as whole grains, fruits, vegetables, meat, fish, eggs, and dairy. In theory, vitamin and mineral supplements should be beneficial for people who subsist on a deficient, unbalanced diet. Health benefits of micronutrient supplementation are less clear for people who consume a balanced healthy diet. Long-term studies of the effects of multivitamin supplements in the U.S. failed to show benefits for health [
99
-
103
]. These data suggest that people who consume a balanced diet do not need to take vitamin supplements. At least, these people cannot expect multivitamin pills to prevent cancer and cardiovascular disease [
99
]. Some studies even show that vitamin supplementation may have
negative
effects on health. Two studies show that beta-carotene supplementation correlates with more frequent occurrence of lung cancer. Another study shows that folic acid supplementation is associated with an elevated risk of precancerous polyps [
99
,
104
]. Other studies have identified higher mortality rates among users of antioxidant supplements compared to control groups [
105
,
992
,
993
].

According to the natural intelligence theory, artificial vitamins and minerals are “unnatural” ingredients that will worsen mental abilities.
^G
I do not consume micronutrient supplements, and when I tried them in the past they did not have noticeable effects on mental state or mental performance. Contrary to my theory, however, some studies have shown that micronutrient supplementation can have beneficial effects on mental abilities and behavior of some segments of the population. There is an excellent review of this topic by David Benton [
106
].

In defense of my theory, I can say that these studies show that micronutrient supplementation is most effective for people who consume a deficient unbalanced diet. The benefits are less obvious for people who consume a balanced diet [
106
,
107
,
938
]. Even in the context of a balanced diet, thermal treatment of food (i.e. cooking) results in partial degradation of some vitamins (by 10 to 30%). Therefore, adding artificial vitamin supplements to a cooked diet may produce benefits. If, however, a person is on a raw balanced diet that is free of pathogens, then supplementation with vitamins will not provide any further benefit and may worsen mental abilities. This is because, in the context of the ancestral diet, all the necessary vitamins and minerals will be present, and supplementation with artificial micronutrients will be unnecessary and “unnatural.” To date there is no experimental evidence to either confirm or refute these suppositions and further studies are needed. Regarding more realistic lifestyles, not all studies of micronutrients show that they improve brain function. For example, a recent randomized controlled trial shows that micronutrient supplementation (vitamins and minerals) does not improve mental development and mental abilities of infants in Zambia [
983
]. Thus, we can conclude that micronutrient supplementation produces small or even undetectable improvement in mental abilities.