No matter, if you read articles written by actual nutritional scientists you'll quickly learn that butter is not back, coconut oil is bad for you and high meat consumption is a terrible idea. But people like good news about their bad habits and no matter what the WHO says, bacon is king. That's totally ok with me, I'm not on a diet, I'm here for the long game and I'm not selling anything. But I do find some of these media stories really interesting. My suspicion is that the reporters don't actually read the studies beyond the conclusion paragraph or maybe the abstract and then write the most click bait headline they can muster. Like this one recently on Forbes telling us that vegetarians on average have a much higher rate of measurable depression.
The great thing about this study is you can actually read it online in full. When you do you'll quickly realize Forbes has overstated the conclusion looking to generate some web traffic. The measured subjects were largely vegetarian (they didn't have enough vegans so they lumped the vegans in with vegetarians) men who were the husbands of pregnant women that volunteered their diet habits in a study not originally meant to measure dietary habits and depression. The authors simply co-opted the data and looked for statistically significant measures they could write a paper on. They say themselves that while nutritional deficiencies may cause the statistically significant depression, that also may not be the case as they have no way of measuring causation. The flaws are apparent in that the food logs are self reported (introducing self reporting bias) and the group was limited to a rather narrow group (men about to be fathers). Further the group of vegetarians were much smaller (350) than omnivores (9318) and only 24 of the vegetarian men as opposed to 366 of the omnivore men were regarded as highly likely to be depressed. There are certainly a lot of depressed omnivores measured in the study we can't forget that a significant amount of people of both demographics are depressed..
Forbes author Alice Walton does admit that plant based diets have health benefits, but shows her ignorance to the diet of vegetarians when she claims that they may be lacking in B12, folate and Omega-3. We can't actually know if any of the men were low in any nutrient, no blood work was done. B12 is certainly present in eggs and dairy products and folate is is easy to consume in fruits and vegetables. While many vegans may be low in B12 (though they shouldn't be) and Omega-3's there weren't many vegans in the study (or too few to measure). Vegetarians themselves don't seem to know how to define themselves and in practice many that call themselves vegetarians eat fish, chicken or animal products and are more "flexitarian." The fact that most people are low in Omega 3 fatty acids seems to elude Walton, and as most people consume vast quantities of Omega 6 in processed foods, their ratios of fat intake are so out of whack that it's safe to say the general population is low on Omega 3. Plant based people can get Omega 3 from algae, ground flax and chia seeds, hemp seeds and mangoes or a simple algae based supplement. Avoiding processed oils will go a long way to improving Omega 3 levels.
The vegetarian depression link isn't new. I've seen this before in an obscure study that also had extremely lopsided groups of vegetarians vs omnivores. The studies tend to use "special populations" in terms of patients at mental health hospitals or groups of people in care of some type. We also know that people often choose plant based diets as either a diet (possibly in pursuit of an eating disorder, a group that has higher rates of depression) or as a result of poor health in an attempt to get healthy. Maybe the causation is reversed in that people that are depressed are more likely to choose vegetarianism in an attempt to feel better. We simply won't know until someone can design a test. In the meantime we'll keep seeing these studies.
Edit: I have found one randomized control study that looked for links between diet and depression. Go read it for yourself. You may feel better about eating plants.
Speaking of which, the media has been all over the PURE study recently stating that low fat diets are a mistake, we don't need as many fruits and vegetables as we think and carbohydrates are bad. This is one of the most widely shared news bites on social media lately as paleo proponents fall all over themselves to post it while consuming butter coffee. Again, this study was designed around self reported diet measures. Health was then followed without follow up on diet changes over several years. I won't get too much into the study and it's faults but it's a great example of how excited people get to share good news about their bad eating habits. Unfortunately adopting the advice you read on news headlines may have detrimental long term health implications. If you're really curious about he PURE study this YouTube video does a good job of breaking it down.
Nutrition is a meandering stream of information in popular media. No matter which way you lean (high fat, low fat, high protein, low carb, etc) you can find information to support your beliefs. What I encourage you to do is use your internal bullshit meter. Are fruits and vegetables really bad for you? Really? Is bacon really good for you? You know the answer without me proving it to you. And if you don't it's ok to live in your cognitive dissonance. Breaking down our diet into fats, proteins and carbs is much too simplistic. We need to be concerned with the quality of our food, not which group it belongs in. If there is a good takeaway from the PURE study it's that we need to be consuming healthy fats. Nuts, seeds, avocado in their whole food form need not be avoided. Processed fats in the form of oils should be reduced or eliminated.