Part C 01

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Answer

A – to find the effect of salt on blood pressure
C – no effects of low glycemic index
C – LDL cholesterol increased in a low – GI diet
B – benefits could be attributed to other aspects
B – inexpensive methods to keeping individuals engaged
B – unchecked consumption of an adverse diet

問題の解説（作成中）

1. A

“The Second Study” に関して言及している部分を読み解くと「Then, we did a second study that addressed the issue you brought up, Norman, which was the effects of salt on blood pressure.」と述べていることが確認できるのでAが正解。
BとCは一つ目の研究として行われた内容なので除外する。

2. C

Aは「people have been espousing a low glycaemic index diet as helpful」と述べているが、研究の成果ではなく、あくまで一般的に人々が持っている認識であるので選ばないように注意する。
Bに関しては「Typically in terms of heart disease what you see are signals related to LDL cholesterol, blood pressure.」と述べられているが、前文に続いた流れで「グリセミック指数がどのように役立つのか」ということを具体的に述べているだけで研究の成果ではないことに注意する。
Cは「 there really were no major effects of the low glycaemic index diets on risk factors for cardiovascular disease」と述べており、4つの目の研究は循環器疾患との関連を調べることが目的だったことと合わせて研究の成果であることが分かるのでCが正解。

3. C

設問のgaugedを「測定する」と考えて「測定された項目は何か」と捉えてしまうと間違える。この設問で問われていることはあくまで「研究で分かったこと（判断されたこと）」である。
Aは「And we really did not see any benefit from the diet that was low in glycaemic index」と、リスク要因ではなくベネフィットに関することを述べているので除外。
Bは測定された内容であり、研究からわかったことではない。また showed a difference in control dietという部分に対する言及はない。
Cは「 It was one of the diets that had a low glycaemic index, and LDL cholesterol seemed to go up, which is the form of cholesterol that is considered bad」と述べられていることから、研究の成果として述べられた事実であることが分かるのでCが正解。

Transcript

Norman Swan:	One of the lead researchers, Dr. Larry Apple, specializes in testing diets.
Dr. Larry:	Previously we had done three major feeding studies. By feeding studies I mean… studies in which we provide everything that a person eats and drinks for a fairly long period of time. Some of our studies have lasted up to half a year. So our first study was DASH, Dietary Approaches to Stop Hypertension, that identified an overall dietary pattern that was helpful in terms of lowering blood pressure and cardiovascular risk. Then we did…
Norman Swan:	Which was a diet low in salt and high in fruit and vegetables.
Dr. Larry:	Actually, it tested attributes of diet other than salt. So salt was held constant, but the diet that was the most effective was the diet that was rich in fruits and vegetables, low fat dairy products and reduced in saturated fat. Then, we did a second study that addressed the issue you brought up, Norman, which was the effects of salt on blood pressure. In that we did a dose response study, and the lower the sodium intake, the lower the blood pressure. Then we did a third study where we said, okay, those diets, the DASH diet is relatively high in carbohydrates, what if we reduce some of the carbohydrate and replaced it with protein or unsaturated fat, mostly monounsaturated fat that you would get from olive oil, for example, looking for the optimal diet to lower blood pressure because blood pressure is such a powerful risk factor for heart disease and stroke. The diets that were higher in protein and higher in monounsaturated fat had a slightly better reduction than the original DASH diet, but not so much that you should say we should change our guidelines. We basically said, you know, if people reduce their saturated fat, they can replace it with carbohydrate, unsaturated fat or protein, which is a good message which gives people flexibility. Then our fourth study was the OmniCarb study. That was a study to look at the effects of glycaemic index on cardiovascular risk factors. And so the idea was to say, okay, people have been espousing a low glycaemic index diet as helpful. Typically in terms of heart disease what you see are signals related to LDL cholesterol, blood pressure. And to our surprise there really were no major effects of the low glycaemic index diets on risk factors for cardiovascular disease. So if you were a participant in our study you would have been randomised to a sequence of four different diets…
Norman Swan:	You were your own control because you went through all four diets yourself.
Dr. Larry:	Right, so you could compare your effects on one diet to the effects on the other diet. So here are the four diets. One is high-carbohydrate, high glycaemic index. That’s what we said was our sort of controlled diet. Then high-carbohydrate, low glycaemic index. Those are carbohydrates that take a bit more time to get into the bloodstream and then you avoid large fluctuations. Then the third diet was low carbohydrate, high glycaemic index, and the fourth and the one that we thought would be the best would be low carbohydrate, low glycaemic index. Okay? So we were really interested in the control versus that one. Each of those diets, by the way, were fed for five weeks. People consumed all five weeks of the diet and then we measured very rigorously, you know, the risk factors; lipids, blood pressure. We measured insulin resistance as well. And we really did not see any benefit from the diet that was low in glycaemic index.
Norman Swan:	Wasn’t there a bit of harm from one of the diets?
Dr. Larry:	I was agnostic on this one, I wasn’t quite sure what the direction of the results would go, but I thought that if anything there would be a signal of benefit, and actually there was a bit of a signal of harm. It was one of the diets that had a low glycaemic index, and LDL cholesterol seemed to go up, which is the form of cholesterol that is considered bad.
Norman Swan:	I think Frank Sacks argues that the categories of food around low glycaemic index, it may well be the fibre in them that’s the issue, not…
Dr. Larry:	Yes, see, this is a common issue with studies of diet or food or nutrients, is that nutrients don’t come in isolation, there are what they call confounding, nutrients travel together. So typically most foods that are high in glycaemic index are low in fibre, and foods that are low in glycaemic tend to be higher in fibre, sort of like the white rice versus brown rice or wholegrain. So that’s where we sort of think this is going. You can get the benefits that we attributed to low glycaemic, by focusing more on other aspects of diet.
Norman Swan:	Moving now to obesity, which you’ve done a lot of research into. You’ve tried behavioural change, you’ve tried feeding diets and so on. How would you sum up the state of the art from your research in terms of what you’ve found?
Dr. Larry:	Doing feeding studies is one of my favourite forms of research because you get clean answers. Our…
Norman Swan:	Except it’s not the real world.
Dr. Larry:	It’s not the real world but it tells you what would happen if you consumed this diet. What you get with behavioural intervention studies is, well, can you in the real world follow a diet? And so individuals have to deal with all of the things that you and I deal with.
Norman Swan:	So have you found in your research behavioural interventions which look promising?
Dr. Larry:	I have done a fair amount of work on helping people who are overweight or obese try to control their weight, and you do get some benefit from various behavioural interventions.
Norman Swan:	Such as?
Dr. Larry:	Well, what we typically try to get individuals to do is to first of all know where their calories come from, so they actually do what we call food records. For some individuals it might be sugar sweetened beverages, other people it might be large portion sizes, other people it might be frequent eating across the day. And then what you do is, working with a counsellor, you identify types of foods, episodes of calorie consumption where you can pull back and where you can make substitutes and do things that are feasible. The challenge is that in order to lose weight you have to have pretty big calorie deficits. So people typically say in order to lose about a pound every other week, you’d need to reduce your calorie intake by 500 calories per day. To do that you really need to track your weight, track your calories. And so we actually embed in most of our interventions now tools to help people self-monitor. The other thing that we do is we try to have some type of continued intervention, because weight loss interventions are not just something that you give it and it’s over, it really requires some efficient way to sort of continue it with fairly frequent contact but doing it efficiently. So instead of having a person either meet you or call you, you have some sort of inexpensive approach to (sort of) keeping you engaged over time, which we think is really important.
Norman Swan:	And very quickly, there’s a huge problem in Australia which is damage to your kidneys which can affect your health profoundly.
Dr. Larry:	Yes, that’s another area of my interest. So I try to look for interventions that are modifiable, and so I’ve been interested in diet, physical activity. With kidney disease it’s probably a mixture of modifiable as well as genetic.
Norman Swan:	You accumulate this: it’s ageing, it’s arterial disease, it’s drugs, it’s all sorts of things that accumulate kidney damage as you get older and increase your risk of heart attacks and strokes.
Dr. Larry:	Ageing represents a cumulative burden of exposures or bad things that have happened to us over time. So if we are consuming foods that damage our arteries or kidneys over time, that will progress. Now, I don’t want to dismiss the effects of diets. There have been other investigators who have focused on diets rich in fruits and vegetables, and there might be a benefit in terms of (what we) called acid-base balance where we are providing some what we call bicarbonate, which is a base that actually helps to preserve kidney function. There’s early evidence, I think there’s a good signal there. But there’s something going on. I can tell you that just in this community around Hopkins there is a very high prevalence of chronic kidney disease, proteinuria which is a manifestation of kidney disease. And many of us think that it’s something about the environment and I personally think it’s an adverse diet that is actually contributing to it.