Health Aspects of Controversial Plant Foods

Grains and legumes are enthusiastically recommended by many mainstream nutritionists as well as whole-food plant-based (wfpb) advocates. Legumes and minimal-processed whole grains may well be healthy for many people. But there are others who have digestive sensitivities to them, and there are some controversial health aspects. So I’ll go over what I have learned about these, as well as plant-based sources of fat, in this post.

Legumes: Beans are Good- (if you are not allergic to them and don’t have sensitivities to them)

One starchy food that is thought by most nutritionists to be good is legumes, a source of low-glycemic carbs. They are eaten in substantial amounts by all the world’s healthiest populations [1]. A study of the diets of elderly people of various ethnic groups in four modern countries showed that higher legume consumption is linked to increased longevity. No other food considered, including meat, fruit, and vegetables, correlated so strongly [2].

Beans are definitely a pre-agricultural food, there is abundant evidence of their consumption in hunter gatherer societies as will be discussed the nutrition post after next on “Pre-Agricultural Nutrition”. Some paleo advocates have argued against legume consumption because they contain phytic acid (also referred to as phytates), which can act as an antinutrient, preventing the digestive system from absorbing certain minerals.

One specific concern expressed is that this antinutrient effect may promote bone loss. But it turns out that higher phytate consumption correlates with better bone health, and it appears the mechanism may be that they block the formation of osteoclasts, the cells that break down bone cells, similar to anti-osteoporosis drugs like Fosamax but without any side effects [3,4]. Phytates are also an antioxidant, which has been shown to be beneficial in cancer prevention [5,6]. And phytic acid appears to only be harmful in excess, while some of us may be deficient in it. An article specifically on phytic acid stated “a subpopulation that might benefit from dietary phytic acid may be aging adults in the developed world [7]. Like me! For those still concerned about possible excess consumption of phytic acid, soaking legumes before cooking reduces its activity [8].

Another concern expressed is that beans contain lectins, which are toxic, but are removed by soaking them overnight or cooking them long enough [9]. While lectins are toxic in high doses, there is evidence that low doses are beneficial, limiting tumor growth and helping with obesity [10], and we don’t exceed these low doses unless we eat a very large amount of legumes.

Beans contain FODMAPs (short chain carbohydrates that are poorly absorbed in the small intestine) which cause their flatulence infamy, although this too can be minimized by soaking. But some people are allergic to FODMAPs, kind of like the legume equivalent of gluten-sensitivity. It is best to avoid legumes if you are allergic, but they are healthy otherwise. Even if you turn out not to be tolerant of beans, you may still tolerate a traditional product made from them like tofu or tempeh.

Soy

Specific concerns are raised about soy products because they are a source of phytoestrogens, which are mistakenly thought to have the same effect as the hormone estrogen. There are two types of estrogen receptor in the human body. Estrogen binds to the alpha receptor while phytoestrogens bind to the beta. These have the opposite effect on health: excess estrogen can cause breast cancer while phytoestrogens do not, in fact are protective against it [11]. And phytoestrogens do not have a feminizing effect on men (“man boobs”) [12].

An additional health issue about soy is whether it is in a natural or highly processed form. Many commercial meat substitutes contain soy protein isolate, hydrolyzed soy protein, or textured soy protein. I was unable to find any research in the literature showing specific adverse health effects of these products, but they are extruded at high heat and the chemical hexane is used in the process so we are getting pretty far away from “minimally-processed”.

I’m dubious about anything that’s made in a processing facility that looks more like an oil refinery than a kitchen. If it’s something that was traditionally processed, and you could make yourself if you wanted, I think it qualifies for minimally processed. Tofu and tempeh are traditional Asian foods made from soybeans. You can make tofu in your kitchen with soybeans and cheesecloth if you know what you’re doing. Tempeh is made from fermented soybeans which is also apparently not hard to do yourself. I believe tofu and tempeh are healthy foods as long as you don’t have any allergies to them. Products made from them are also healthy, although I’d stick with organic sources like Tofurky.

Meat Substitutes

There are acceptable meat substitutes on the market (from the standpoint of minimally processed, no refined carbs) that are good vegan protein sources. I also recommend them for anyone trying to reduce meat consumption, although you can also cut back on meat by stretching it in recipes. Many meat substitutes are delicious and have a meat-like texture. Some of them are quite healthy, in my opinion, some not so much. The ones to consider avoiding or eating in moderation are made from soy protein isolates, discussed above.

Because of the controversy over soy, and the fact that some people are allergic to soy, some commercial brands of meat substitutes are going with pea protein isolate, which, as near as I can tell, is a good alternative as long as it hasn’t been chemically isolated. Unfortunately you can’t always tell that from the label.

Seitan is a more modern term for a traditional Japanese product called Fu. It is made from vital wheat gluten, which is protein extracted from wheat. Seitan is pronounced like “satan” and from some of what you see about it on the internet, many feel that’s appropriate. It certainly should be avoided by people with gluten sensitivity. But there is a gluten-free substitute called OrgraN from Australia, which you can get from Amazon. We discuss the pros and cons of grains below. For those without digestive issues with them, who think grains are ok in moderation, vital wheat gluten seems to be a healthy protein source.

Tofurky makes a substitute turkey from tofu, that’s where they got their name. They have a meatless version of a Thanksgiving turkey feast that even includes little cutlets shaped like drumsticks. They also make ground beef and chicken substitutes. I mostly use their sausages which are delicious. They are made from organic tofu, expeller pressed canola oil, and spices. Canola oil itself is controversial, but as discussed below, I consider organic expeller pressed canola to be ok in moderation. Some of Tofurky’s products also contain vital wheat gluten.

Sweet Earth makes “harmless ham”, “benevolent bacon”, and substitute meat strips, all from vital wheat gluten and other organic ingredients and oils like extra virgin olive oil (evoo). Their veggie burgers are made with organic vegetable and grain ingredients and I consider a healthy food for those of us who can digest grains well.

A final caution about using meat substitutes: They don’t always perform in recipes the way you think. My wife Karen makes a delicious spaghetti sauce with sausage and ground beef. I once tried substituting Tofurky sausage and their ground beef substitute. It was fine when I first made it. But when I tried to reheat the leftovers, the sausage and beef substitute had disappeared into the sauce, which now tasted like marinara sauce thickened with an unrecognizable paste. So if you try this, better to keep the meat substitute separate till the last minute.

Grains

Refined grains have the problem of causing a blood sugar spike as discussed previously. They are also inflammatory, and contribute to a number of health conditions such as obesity, diabetes, and heart disease. In contrast, minimally processed grains have a low glycemic load, and consumption of them is associated with lower risk of disease [13].

The same concerns are raised about antinutrients in grains, including phytic acid and lectins, which we already discussed under legumes. Grains are also suspected of contributing to leaky gut in susceptible people: “the consumption of wheat, but also other cereal grains, can contribute to the manifestation of chronic inflammation and autoimmune diseases by increasing intestinal permeability and initiating a pro-inflammatory immune response” [14], leading to conditions including Crohn’s disease and other inflammatory bowel diseases, and irritable bowel syndrome.

In addition, some people are allergic or have sensitivities to grains, like gluten sensitivity, or in its more severe form celiac diseases. There is evidence that gluten sensitivity is worse for modern hybridized wheat, so alternative grains or “ancient grains” may cause less of a problem [15]. There is also some evidence that yeast is also a trigger for inflammation in Crohn’s disease, so some people may be able to tolerate foods with grains as long as they don’t contain yeast [16].

It also needs to be mentioned that animal products are also an important factor in promoting Crohn’s disease, and for many people with Crohn’s, a plant-based diet is more beneficial than avoiding grains [17]. If you suspect you may have Crohn’s disease you could also do a “belt and suspenders” approach and reduce consumption of animal products and grains. Minimally-processed grains are a healthy food as long as you are not one of the people with these digestive issues. In his book Wired to Eat, Rob Wolf points out that many people may have digestive sensitivity to grains and not be aware of it, as has been his experience working with clients, and not all issues are caught by testing. You could always try avoiding them for a couple of weeks and see if you feel better, then carefully reintroduce them and see what happens. Working with someone experienced with food allergies during this period would be advisable.

There are a lot of gluten free and “pseudo-grain” options available if they are a problem for you. One of the major benefits claimed for whole grains is fiber, but there are many grain-free high-fiber sources, including: many salad greens like endive, broccoli, raspberries, blackberries, avocados, flaxseeds, chia seeds, pears, apples, strawberries, figs, almonds, and buckwheat (a pseudo-grain made from a seed). Buckwheat is a staple in Eastern Europe, where it is called kasha, and in Japan, it is used to make soba noodles.

Controversial Plant-Based Fats

As background I first have to cover the different types of fats. I won’t go over saturated fats here because they are controversial enough to need there own future post. That leaves trans-fats, polyunsaturated, and monounsaturated fats.

Fat is an important nutrient. It’s unfortunate we don’t any better word for it because even the name can bring up negative images, like bacon grease congealed in a pan. Yuck! We went through a low fat era and it has left many people fat phobic. To this day I have to catch myself reading an author who proposes low-carb/high-fat: “More than 50% fat. Are you crazy? OK, calm down, he says it’s healthy fat, let’s hear what he has to say”.

There are good and bad fats, and you can eat a decent amount of good fat and still be healthy and lean. To understand good and bad, it helps to know how heart disease actually happens, which is will be discussed in an upcoming post about saturated fat. And bad fats contribute to chronic inflammation, which we’ve already seen is bad.

Trans-fats: very bad. There is overall consensus that trans-fats should be avoided like the plague. Some authors call them the ugly fat. They promote inflammation, heart disease, and other diseases. The main source of trans fats in the diet is hydrogenated vegetable oil, found in processed foods and my grandma’s tub of Crisco.

In the US we’ve finally gotten around to labeling trans fats, so you should look for 0 grams. But it can still be misleading, manufacturers are allowed to round it off to zero if it’s less than 1 gram per serving. So if you do use processed food, avoid anything that has hydrogenated in the label. But trans fats also occur from the high heats used to process commercial vegetable oils which is why expeller pressed oils are recommended instead, and they can occur from cooking unsaturated oils (especially polyunsaturated) at too high of a temperature [18].

Omega3 and Omega6 Polyunsaturated Fats:  Vegetable oils are polyunsaturated, and there is also polyunsaturated fat in animal products. Polyunsaturated fats contain omega3 and omega6 fatty acids. Too high of a ratio of omega6 to omega3 in your diet is inflammatory, leading to many health issues including heart disease and arthritis [19]. The ideal proportion is thought to be around 1:1, while when eating SAD we may be closer to 20:1. Most vegetable oils have a high ratio, the exception is canola which is 2:1 (canola is controversial as discussed below). Fatty fish are high in omega3 as long as they are wild and not farmed [20], and so are walnuts and flax and chia seeds (you have to grind the seeds before eating so your body absorbs the omega3).

Omega3 is why there is a recommendation to eat fish oil. Because of concerns over mercury and other pollutants, it is good idea to find a source that has been molecularly distilled or independently tested not to have pollutants [20]. In the US we have “USP certified”, and there are quality mail order varieties like Nordic Naturals.

There is a whole other discussion about the benefits of fatty acids like ALA, DHA, and EPA [20] (types of omega3) and their health benefits. Plant sources like walnuts and flax do not provide DHA or EPA, just ALA, and your body will convert the ALA to DHA and EPA, but inefficiently. So there is some concern over getting enough DHA and EPA if you are vegan or following a wfpb diet with a low amount of animal foods. This can be addressed by taking supplements sourced from algae [21].

Dairy and beef both contain unsaturated fats as well as saturated. If they are from grass fed animals they contain a higher percentage of omega3 fatty acids compared to commercial grain fed products, which are high in omega6, which is the reason for the recommendation to eat grass-fed. Monounsaturated Fats are present in large percentage in olive oil, nuts, avocados, and canola oil, and other vegetable oils labeled “high-oleic”. Oleic acid is an omega9 fatty acid, and is considered to be generally beneficial [22].

Monounsaturated Fats are present in large percentage in olive oil, nuts, avocados, and canola oil, and other vegetable oils labeled “high-oleic”. Oleic acid is an omega9 fatty acid, and is considered to be generally beneficial [22]. Monounsaturated fats have healthy properties including decreased risk for breast cancer (especially if the monounsaturated fat replaces polyunsaturated fat in the diet [23]), and improved glycemic control in diabetics [24].

So now we can bet back to discussing plant-based sources of fats.

Olives are undoubtedly healthy, but olive oil is still a processed food, although in its extra-virgin form (or “evoo”), it is one of the least processed plant oils. It can contain up to 20% saturated fat. If you’re concerned about that you can find varieties with as low as 7½%. Many nutritionists consider evoo healthy, especially because of its monounsaturated fat content, and it is a well-known part of the Mediterranean diet.

Others, like some wfpb authors, consider it unhealthy (though maybe “less bad” than other sources of fat like animal products or other vegetable oils). They are also concerned that people think it makes all your food more “heart healthy” if you pour olive oil on it (like sopping bread in it as you’ll see people do at restaurants).

I grant them that point. But if you want to claim that all oils are unhealthy and you should eat all of them in moderation, I’d argue that evoo is among the “least unhealthy”. If you want to use a bit of oil to get you to eat more healthy foods, evoo is a good choice. It’s what I put in my refillable oil sprayer to sauté veggies.

Coconut oil is predominantly saturated fat, but also contains some medium chain triglycerides (MCTs) which have beneficial properties. It is often claimed to be a healthy oil. High consumption of unprocessed coconuts appears to be healthy for Pacific Island populations like the Tokeluans [25] and Kitavans [26], but I don’t know of studies proving this to be true for coconut oil, a processed food from coconuts.

As for the MCTs, coconut oil actually contains a small percentage of these. It does contain a large amount of lauric acid, a medium chain fatty acid, but that is not the same as a medium chain triglyceride. A review of how it is metabolized concluded: “It is therefore inaccurate to consider coconut oil to contain either predominantly medium-chain fatty acids or predominantly medium-chain triglycerides. Thus, the evidence on medium-chain triglycerides cannot be extrapolated to coconut oil” [27].

Other than the relatively high saturated fat content for a plant oil, I have not seen evidence for coconut oil being particularly unhealthy either. Its status appears to depend on the science concerning saturated fat, which itself is controversial and will be discussed in the next nutrition post.

Canola oil is a vegetable oil made from the rapeseed plant, which contains erucic acid (which has deleterious health effects). Canola was developed by hybridizing (through cross-breeding) the rapeseed plant to obtain a much lower erucic content (about 4% of that of rapeseed oil), and the name canola is short for “Canadian oil low acid”. This is the only vegetable oil with a good ratio of omega6 to omega3 (a 2:1 ratio).

This oil is controversial. Many people rail against it, making it seem like a frankenfood. One reason is the erucic acid content, but it has been specifically bred to minimize that. The other reasons given to avoid it are the same reasons to avoid any commercially processed oil, so I don’t get why canola is singled out. If you use organic, expeller pressed oil, it is not genetically modified, nor has it undergone any high temperature processing or deodorization, nor will it contain trans fats.

I have not seen any reasons given why the organic, expeller pressed form of canola is bad for you. A final note on canola oil is that there was a significant amount of it used in the Mediterranean-style diet in the Lyons heart study [28], which showed drastically reduced heart disease risk compared to the control group on a diet similar to the SAD. Not bad for a frankenfood. But again, canola oil is not a whole food so should be used in moderation.

Aside from whole coconuts and olives, other whole sources of plant fats include avocados, nuts, and seeds, all of which are generally agreed to be healthy.

Fats and Endothelial Function

Arteries are capable of expanding (dilating) in response to blood flow, triggered by healthy functioning of their inner layer, the endothelium. Not only are they flexible but they are active tissue that responds to nitric oxide released by the endothelium by expanding. This response is called flow-mediated (vaso)dilatation, or FMD. Consumption of a high fat meal significantly impairs FMD for several hours [29]. This happens whether it is saturated fat or vegetable oils, including extra virgin olive oil. This effect does not happen for evoo combined with vegetables at a meal [30], or if vinegar, especially red wine or balsamic vinegar, is consumed along with the evoo [31]. The vinegar effect can also be replicated by just eating red grapes [32].

Degraded endothelial function is a symptom of coronary artery disease (CAD) [33]. I have not seen proof that the short-term impairment of endothelial function after a meal leads over time to chronic impairment, which could result in CAD. But most authors seem to assume that is does, which may be because high fat consumption also raises markers of inflammation and oxidative stress in the same time period the arterial stiffening is occurring. The markers are not raised if the fat is from a whole plant-food source like avocados or whole olives [34].

It is suspected that the rich amount of healthy phytochemicals in the whole plant food cancels out any negative effect of the fat. I haven’t found references that the combination of saturated fats and plant foods blunts the effect on FMD also, but it seems logical that it would. So veggies sautéed in butter would have saturated fat but might have a more benign effect on FMD than a hamburger by itself.

The effect of fat on FMD is one reason why some wfpb proponents like Dr. Caldwell Esselstyn advise minimizing consumption of all fats including added oil. Dr. Esselstyn treats patients with advanced CAD, many who suffer from angina. In their case, impaired FMD after a meal could trigger an angina attack and should clearly be avoided. For the rest of us, it might be ok to loosen up from Dr. Esselstyn’s  “no oil” to “oil in moderation”, especially if we make sure to consume veggies or vinegar with the oil.

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