Q6 - Dietitian: High consumption of sodium

[ManhattanPrepLSAT1]

6. (E)
Question Type: Assumption
Potassium prevents the malign effects of sodium, therefore, you should eat fresh fruits and vegetables rather than canned fruits and vegetables. This argument only makes sense if we assume that the fresh fruit and vegetables have more potassium than the canned fruits and vegetables. Answer choice (E) expresses this.

(A) is incorrect. It’s good that fresh fruits and vegetables contain more potassium than sodium, but that doesn’t make fresh fruits and vegetables better for you than canned fruits and vegetables.
(B) is out of scope. It’s totally irrelevant whether or not processing businesses often add sodium to foods being canned or frozen. It would be much more important to know whether or not they were adding potassium.
(C) is out of scope as well. Maybe some minerals other than potassium can prevent sodium’s malign effects. It doesn’t matter. This argument is about potassium and its specific effects.
(D) is out of scope. This answer choice does not address a difference between fresh and canned/frozen fruits and vegetables.


#officialexplanation

[perfectparadise1]

Something about this question bothers me. Nowhere in the argument does it say that more Potassium is better. The potassium in fresh fruit may be LESS but more readily bioavailable. Too much Selenium will kill you but 50mcgs a day works as a great antioxidant. If this was a suff assumption me and Q 6 would be cool, I'd even take it out for a beer. But the stem says REQUIRED and I see no way in which it is REQUIRED that fresh fruit have more potassium than canned fruit without a premise delineating the requirement of Potassium needed by someone like Dick Cheney.

[farhadshekib]

Something about this question bothers me. Nowhere in the argument does it say that more Potassium is better. The potassium in fresh fruit may be LESS but more readily bioavailable. Too much Selenium will kill you but 50mcgs a day works as a great antioxidant. If this was a suff assumption me and Q 6 would be cool, I'd even take it out for a beer. But the stem says REQUIRED and I see no way in which it is REQUIRED that fresh fruit have more potassium than canned fruit without a premise delineating the requirement of Potassium needed by someone like Dick Cheney.

I got this question wrong because my thought process was similar to yours, but let's break it down.

Premise: potassium in plant foods {a general term which includes both fresh and frozen/canned plant foods} helps to prevent sodium's malign effects.

Conclusion: Some people who want to maintain cardiac health without lowering sodium consumption (sodium consumption could stay the same or it could increase) should consume fresh, rather than canned or frozen, fruit and vegetables.

At this point, the author seems to suggest that potassium in plant foods - a term that includes fresh/frozen/canned plant foods - seems to fight sodium's negative effects. Yet the author concludes that one form of plant food (i.e. fresh) is better than another (i.e. frozen/canned).

As you read this, you may have noticed a major gap in the argument: the premise does not really support the conclusion.

The argument does not mention what's so great about fresh fruit/vegetables... in other words: why should we choose it over its canned/frozen counterparts.

(E) serves to fill this gap.

Picture it this way:

P1: potassium in plant foods helps to prevent sodium's malign effects.

P2: "fresh fruits and vegetables contain more potassium than do canned or frozen ones" .

C: Therefore, some people who want to maintain cardiac health, w/o lowering sodium consumption, should choose fresh, rather than canned or frozen, fruit and vegetables.

Doesn't the argument sound a lot better now?

If we negate (E) - that is, fresh fruit and vegetables do not contain more potassium than do canned/ frozen fruit and vegetables - then the argument is significantly weakened.

The author's conclusion would not logically follow from the premise.

Even if you don't feel that (E) is necessary for the argument, it is by far the best answer choice.

[jgallorealestate]

What if fresh fruit and vegetables has a higher proportion of sodium/potassium?

Who cares that fresh fruit has more potassium than canned fruit?

Example: Fresh fruit= 1000g sodium, 15g potassium

Canned fruit=10g sodium, 10g potassium

This shows that the answer choice is not a necessary assumption and can be destroyed, even if assumed. We're concerned with the proportion of potassium/sodium.

[eapetrilli]

You make an interesting argument and I have noticed that some necessary assumption questions, and must be true as well, simply fall short of 100 percent provabilitity. It's useful to keep in mind that on assumption family questions we don't want add an additional layer of reasoning. (E) is the best of the choices. In order for (A) to be correct we would first have to assume that the argument rests on a proportion, and then we have to make an assumption about the proportion in canned fruit because this is never mentioned on the answer choice.

This argument doesn't require an assumption about proportionality because the support for the conclusion rests on potassium having this mitigating factor, and you have to address the movement from that premise to the conclusion to consume fresh rather than frozen fruit BECAUSE of that premise and not for any other reasons. We need an assumption to show that fresh fruit has more of this mitigating factor, and not necessarily that it better reduces the chance of heart disease, because that is not the conclusion.

Stick to the path of least resistance on these first ten or so questions in the section. HTH!

[sch6les]

We can explain this question via formal logic:

(1) potassium in food => help negate sodium's negative effects => help maintain cardiac health
---
(2) eat fresh; don't eat canned/frozen => help maintain cardiac health

Necessary and sufficient assumption: eat fresh; don't eat canned/frozen => potassium in food
Contrapositive of above: ~(potassium in food) => ~(eat fresh; don't eat canned/frozen)

In English: If you eat fresh foods, you are getting potassium. If you only eat canned or frozen plant foods, you are getting no potassium.

From here, you can get (E). If fresh foods have potassium, and canned and frozen foods don't have potassium, then obviously fresh foods have more potassium than canned and frozen foods.

[jm.kahn]

What if fresh fruit and vegetables has a higher proportion of sodium/potassium?

Who cares that fresh fruit has more potassium than canned fruit?

Example: Fresh fruit= 1000g sodium, 15g potassium

Canned fruit=10g sodium, 10g potassium

This shows that the answer choice is not a necessary assumption and can be destroyed, even if assumed. We're concerned with the proportion of potassium/sodium.

This is what I thought as well. E doesn't have to be necessarily true. Any convincing explanation?

This argument doesn't require an assumption about proportionality because the support for the conclusion rests on potassium having this mitigating factor, and you have to address the movement from that premise to the conclusion to consume fresh rather than frozen fruit BECAUSE of that premise and not for any other reasons. We need an assumption to show that fresh fruit has more of this mitigating factor, and not necessarily that it better reduces the chance of heart disease, because that is not the conclusion.

This doesn't seem right. Potassium can be a mitigating factor and proportionality can still play a role. 15g potassium may be better than 10g potassium as long as the sodium remains constant at 10g, but 15g potassium can be way worse than 10g potassium if canned fruits have only 10 g sodium but fresh vegetables have 10000 g sodium.

We can explain this question via formal logic:

(1) potassium in food => help negate sodium's negative effects => help maintain cardiac health
---
(2) eat fresh; don't eat canned/frozen => help maintain cardiac health

Necessary and sufficient assumption: eat fresh; don't eat canned/frozen => potassium in food
Contrapositive of above: ~(potassium in food) => ~(eat fresh; don't eat canned/frozen)

In English: If you eat fresh foods, you are getting potassium. If you only eat canned or frozen plant foods, you are getting no potassium.

From here, you can get (E). If fresh foods have potassium, and canned and frozen foods don't have potassium, then obviously fresh foods have more potassium than canned and frozen foods.

this is also not a correct explanation. The argument does allow you conclude that canned and frozen foods don't have any potassium.

[jeff.wongkachi]

Just did this PT today and got this right. I quickly eliminated C and D before just feeling like E was "More important". Looking back at A) and B) during review, it seemed that A and B were at most partial answers, whereas E was the full answer.

A) Just because Fresh F&V has more potassium than sodium, it doesn't mean it has more potassium than canned/frozen.
B) Even if we saw this as a reason that canned or frozen foods were bad, it doesn't mean that fresh is the better choice
C) Sure, but this doesn't indicate why Fresh>Frozen/Canned
D) 100% out of scope
E) directly compares fresh v frozen/canned, saying it has more of what helps prevent sodium's bad effects. Without this assumption (That fresh, essentially, is better than canned/frozen), this argument does not work

Does this make any sense?