Inductivist

Nuts are supposed to be good for you (I recently posted on a meta-analysis that found that walnuts lower total and bad cholesterol and triglycerides), but they are high in calories. Do they make you fat and bushy like a well-fed squirrel?

A new meta-analysis of thirteen randomized clinical studies (741 people) looked at the issue. It found that nut consumption did not affect body mass index (BMI), weight, percent body fat, or waist circumference. So if you like this kind of food and think it's beneficial, go nuts. 

Don't make the mistake of assuming this is a health blog when you see two health posts in a row.  I do have the goal of reporting the results of new, interesting meta-analyses. If you focus on one study, you can find whatever results you'd like, but dozens of studies, especially large, random clinical trials? That's more convincing. Facebook should give me a fantastic reputation score. No Fake News here.

This new meta-analysis is not great, but its five cross-sectional and two intervention studies are worth mentioning. Both types of studies find that greater intake of vegetables does not lower triglycerides--the major form of fat stored by the body, which my doctor keeps telling me is way high in my blood. (Turns out, I have a bad gene.)

On the other hand, the more servings of fruit you eat per day, the lower your triglycerides. Two trials is not nearly enough, but, still, the results are interesting.

The authors do not have much of an explanation of how fruit helps, but they do describe an animal trial that found that high fruit fiber intake lowered triglyceride levels in the following order: pomegranate > apple > strawberry > guava > papaya > mandarin and orange.

This new meta-analysis (more than 430,000 participants) addresses the question, Does it matter whether you eat a lot of carbs?

The researchers found a U-shaped curve: people were most likely to die if their diets were carb-heavy, or if they ate mostly fats and proteins. The subjects with the lowest odds of dying ate 50-55% of their calories in carb form.

The source of the macronutrients also matters. Mortality goes up if you eat fewer carbs but more of the fats and proteins come from animals; the risk falls as the fats/proteins are plant-based.

So, the story here is pretty conventional: carbs are good at moderate levels, while more fats and proteins ought to come from plants.

Typical of even medical research, the authors do not stress the possibility that people with genes that make you live to a ripe old age also eat more plant-based food. We know from research that high conscientiousness, which is highly influenced by genes, is associated with a long life. Good genes might: 1) motivate you to closely follow medical advice, and 2) extend your life. What you eat might not make any difference.

If that possibility sounds depressing because you can't switch out your bad genes, well I ain't here to make you feel good.  

UPDATE: I should let you know that my diet ranges from minimal carbs to low carbs depending on my level of discipline (lots of carbs makes me feel lousy, and I put on weight), so I have no bias in favor of the results of this study.

This new meta-analysis of 54 randomized studies looked to see which oils improve your cholesterol the best.

The authors found that you can bring down your bad cholesterol (LDL) by eating the following oils instead of butter: safflower, sunflower, canola, flaxseed, corn, olive, soybean, palm, coconut, and even beef fat. All these were better than butter for total cholesterol, and safflower, sunflower, canola, corn, and soybean oil beat lard for total cholesterol.

Compared to lard, safflower, sunflower, canola, corn, and soybean did better on LDL. And sunflower was better than olive and palm oil.

For raising the good cholesterol (HDL), safflower turns out to be the loser. Sunflower, olive, palm, coconut and even beef fat are improvements. Sunflower, olive and beef fat are better than soybean. Coconut and palm beat soybean as well as corn oil. The researchers, however, say there's evidence that high HDL might not reduce your cardiovascular disease risk, so LDL seems to be more important.

For triacyglycerols--fat levels--sunflower, soybean, and palm oil are superior to butter, while safflower, sunflower, corn, soybean, and palm are better than beef fat.

Maybe you didn't need all that, but the big depressing news is that butter--which I love--stinks, and it looks like sunflower oil is the grand champion. I don't see it around as much as other oils, but according to experimental research, it seems to be the healthiest choice.

Myself, I like it when science contradicts the cool people who tell me I need to eat olive and coconut oil 24/7.

UPDATE: The Russians like sunflower oil, but I swear I did not post this research because they have something on me.

I am always looking for easy eating choices that are good for you. This new meta-analysis of 26 clinical trials looked to see if walnuts make a difference. The authors found that daily consumption of walnuts significantly lowered total cholesterol and LDL cholesterol--the "bad" stuff that clogs arteries. It also reduced triglycerides or fats in the blood. HDL, the "good" cholesterol, remained unchanged.

The researchers found that subjects who ate enough walnuts so that it was 10-24% of their daily energy intake got more benefit than those at the 5% level. So for someone about my size--5' 10", 180 pounds--you should probably eat roughly 2 ounces per day.

Of course, all of this assumes that conventional medicine is right about cholesterol and triglycerides.