Nutrition size which he believed is responsible for the

Nutrition is the study of diet and its impact on people’s
health. Lynn (1990) suggested that nutrition could have a major impact on IQ,
specifically it could be a cause for the Flynn effect (Maltby, Day &
Macaskill, 2013, p. 327). Areas of nutrition that have been looked at for their
impact on IQ are: breastfeeding, deficiencies and the mother’s diet are a few.
While the evidence found can be used to help people, it can also have major
impacts within the general population, which will be further discussed. Overall,
the evidence found suggests that there is a major link between nutrition and
IQ.

Lynn (1990) found there has been an increase in height in
humans within the century which could be down to nutrition, specifically people
have been drinking more milk, which is linked to growth and development, and
people have increased their consumption of fruit and vegetables (Maltby, Day
& Macaskill, 2013, p.327). If nutrition can have this kind of effect on
height average over time, then why can’t it be linked to the increase in brain
development and the increase in IQ. The Flynn effect shows that the mean IQ for
countries has been increasing over time (Flynn, 1984a). Lynn (1990) found an
increase in brain size which he believed is responsible for the higher
intelligence and increase in IQ. Lynn’s theory suggests that good nutrition
should be linked to larger brain sizes, which was found in the evidence, and
therefore increased intelligence. Malnutrition was also found to link with poor
development of the brain. However, evidence by Peters (1991) directly
contradicts this and suggests that there isn’t a link between brain size and
intelligence. A major problem with both Lynn (1990) and Peters (1991) is they
look at the relationship between brain size and intelligence using a
correlation. With correlations, you cannot determine cause and effect, which
means that while Lynn (1990) finds a relationship, you are unsure if the large
brain size causes higher intelligence or the higher intelligence caused the
person to develop a larger brain. The same problem occurs with Lynn (1990)
suggesting that nutrition causes the increase in IQ. In order to address this
problem, an experiment should be carried out, however there may be ethical
issues if you were to hold back on certain nutrients that increase IQ. Breastfeeding
and the use of supplements have been found to increase IQ scores (Oddy et
al,2004;). Its possible that over time more people have been breastfeeding and people’s
health has gotten better, which has caused the increase in IQ over time.

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Breastfeeding is found by multiple studies to have positive
effects on IQ (Oddy et al, 2004). This study found that if breastfeeding was
stopped at a time considered early, there was a decrease in intelligence. If a
child was breastfed for longer, for example another 6 months, their verbal
intelligence was higher (Oddy et al, 2004). This evidence suggests that
breastfeeding your child increases their intelligence. Its possible that more
people breastfed, which has caused the increase in IQ scores. The nutrition of
the children would overall be better with breastfeeding, which supporting that
nutrition increases intelligence. A study by Smith et al (2003) supports these
findings. However, a problem with this study is they used low birth weight
children. This could have caused the difference in scores, rather than
breastfeeding. Also, these studies tend to show the short-term benefits of
breastfeeding. Typically, children not breastfed will catch up with those that
were (Mortensen et al, 2002). A meta-analysis by Jain et al (2002) found that
when studies were of a “higher quality”, there was no link found between
breastfeeding and intelligence. This suggests that possibly earlier evidence
may not be reliable. A major problem with the evidence by Oddy et al (2004) and
Smith et al (2003) is they fail to control for other major factors, that could
cause the difference in intelligence scores, rather than it being nutrition. When
these other factors are taken into account, the effect disappears. For example,
Der et al (2006) found that IQ scores for children who were breastfed were
higher, but mothers also had high intelligence. When this was controlled for,
the effect was not found. This suggests that rather than breastfeeding being
the cause for higher intelligence, it was more to do with the mother’s
intelligence. This doesn’t support that nutrition increases IQ. A recent study
by Furman (2017) suggests that women who are young and unmarried tend not to
breastfeed. This could also be causing the effect shown between IQ and
breastfeeding, or even socioeconomic status could be the cause. This is a major
problem with using correlations as evidence, cause and effect cannot be
established. However, overall evidence suggests that there is a link between
breastfeeding and intelligence in children, therefore nutrition contributes to
intelligence.

Deficiencies of important minerals or vitamins have been
found to also link to IQ. Lack of particular minerals are thought to have
negative effects on IQ (Maltby, Day & Macaskill, 2013, p. 329). Iodine has
been found to be important in health and is linked to the production of
hormones. Evidence by Qian et al (2005) found that children whose mother took
the iodine supplements before birth, and the children were given it after as
well, had higher IQ. This suggests that iodine has an important effect on
intelligence. However, its possible that the effect is more to do with the
hormone produced by the use of iodine, rather than iodine itself. Taking
supplements to improve IQ has also been looked at. Specifically, Benton and
Roberts (1988) looked at the effect of supplements, which included important
vitamins and minerals. They found that those who took the supplements had
improved in non-verbal intelligence. However, a problem with this is that the
difference found was not significant. Benton and Roberts (1988) still published
it and caused major controversy. This study has some issues, and is not a
reliable piece of evidence due to the monetary benefit this study gained and
its methodological issues. To address these issues studies have attempted to
replicate the study in order to clear up any issues regarding supplements and
their impact on IQ. Evidence by Schoenthaler et al (2000) found that when given
vitamin and mineral tablets, children had higher non-verbal intelligence
scores. This suggests that vitamin and minerals have an important effect on IQ,
therefore supporting that nutrition has an important effect on IQ. However, a
problem with this study is the children used in the study were already
malnourished and any effect here would be far greater than Benton and Roberts
(1988) original study. The replication here therefore does not help to clear up
any confusion. Evidence by Crombie et al (1990) found no significant effect of
supplements on IQ. This therefore does not support previous evidence. Overall,
the evidence found does suggest that taking supplements helps to improve IQ and
has a positive effect on IQ. However, it would be a good idea if further
research was conducted within this area, using different samples and
supplements, to add to the pool of research.

Breastfeeding and vitamin supplements have been found to
have a positive effect on IQ. A mother’s diet can also have a major impact on
IQ. While it may not necessarily relate to the nutrition once the child is
born, but it is the nutrition of the mother which can have a major impact on a
babies’ health and IQ (Maltby, Day & Macaskill, 2013, p.347). It has
already been highlighted that when the mother takes iodine supplements, this
increases the child’s IQ (Qian et al (2005), showing that mothers nutrition can
have a positive effect on IQ. However, there are ways that a mother’s diet can
have negative effects on a child’s IQ. For example, if the mother were to drink
alcohol when pregnant, this can have very negative effects on the babies’
development, including the brain. Therefore, it can have a negative impact on
IQ (Maltby, Day & Macaskill, 2013, p.347). Evidence by Kodituwakku et al
(1995) found that drinking in pregnancy caused impaired cognition in the child,
otherwise known as Fetal alcohol syndrome. However, any link between
intelligence and drinking seems to be unclear, but you would assume that a decrease
in cognition would also mean a decrease in IQ and intelligence.  Research in this area seems to suggest that
there is no link between alcohol consumption prenatally and IQ (Bailey et al,
2004; Jacobson et al, 2004). However, the evidence suggests that there could be
an important link between a mother’s diet and the intelligence of the child.

The evidence from breastfeeding could have a major impact on
the way people think in the general population (Oddy et al, 2004; Smith et al,
2003). It may cause women to breastfeed more, thinking that they should. It
could even lead to the shaming of mother’s who do not breastfeed, even if
there’s a medical reason for them not breastfeeding. This is why researchers
should be careful and not say people have to breastfeed in order for their
child to be intelligent, as evidence has been found that non-breastfed children
tend to catch up with those who were breastfed (Mortensen et al, 2002). If they
aren’t careful, this could have major effects on the general population and on
the mental health of the women who don’t/can’t breastfeed. This will happen if
the media is involved. Evidence found that when less women were shown to be
breastfeeding in a magazine, the levels of women breastfeeding decreased (Foss
& Southwell, 2006). This shows that media can have an impact on the view of
breastfeeding. Evidence that supplements can increase IQ can also have a big
impact on what people think about vitamin and mineral supplements. The evidence
by Benton and Roberts (1988) was published on television and was shown to the
majority of the general population, despite there being no significant
difference being shown. It caused more people to buy supplements, for their
children. This suggests that it changed the way people thought about
supplements, and they believed it would make their child more intelligent. The
problem with this is when replicated, no difference was found. This tells us
the research was methodologically flawed and the researchers interest was to do
with publicity and its monetary benefits. When it comes to iodine supplements,
the evidence suggests that there is a link between iodine and IQ (Qian et al,
2005). This will affect the general population as people will take more iodine
supplements, or give them to children in order to improve their IQ. If this has
a major effect, this could be one of the causes of the rise in IQ. Not only is
this evidence for nutrition being a cause for the increases in IQ, but this
evidence specifically shows how important it is that mother’s take care of
their diet when pregnant. Women are told not to drink alcohol when pregnant as
it can have major effects on the development of the baby. If told it will
decrease the baby’s intelligence and cognitive functions, this would have a big
impact on peoples thinking.

The evidence suggests that there are links between nutrition
and IQ, particularly breastfeeding and iodine supplements. There are also links
between a mother’s diet and the intelligence of the baby. Any research can have
major impacts on the way that people think about nutrition and IQ, particularly
their beliefs. If the media is involved it can have large effects on this.
Research should be careful to not give out false information, which could have
potentially damaging effects, if the findings are wrong. Overall, studies show
that there is a relationship between IQ and nutrition, however some are
contradictory. This is why this area should still be looked at to see the
effect of nutrition on IQ over the years.