Why are cruciferous vegetables important in a ketogenic diet?
There is a wrong way and a right way to do keto.
The wrong way is high protein and little to no vegetables.
Doing keto the right way—the Plant-Based way—necessarily requires that most of the carbohydrate you consume will be from non-starchy, nutrient dense, leafy green vegetables.
And, well, most of those leafy greens are in the Brassica family—the cruciferous vegetables.
Cruciferous vegetables include kale, cauliflower, Brussel Sprouts, broccoli, bok choy, and cabbage. There are many more, but these are some of the more common.
Cruciferous vegetables are nutrient dense because they contain vitamins, minerals, low-sugar carbohydrate, and fiber.
But they also contain other molecules, phytonutrients, that have been studied for their effects on everything from cancer to estrogen balance. Let’s look at a few…
The Isothiocyanate group contain phytonutrients like sulfuraphane, phenethyl isothiocyanate and benzyl isothiocyanate.
Studies done on this class of phytonutrients show them to be effective inhibitors of cancer cell lines in lung tumors, multiple myeloma, human bladder cancer, all GI cancers (esophagus, stomach, small intestine, and colon), and mammary gland tumors.
There seems to be more than one mechanism of action.
First, many act as antioxidants binding up free radicals like Reactive Oxygen Species (ROS) which can cause DNA damage.
Second, they influence epi-genetic enzymes like histone deacetylases. These enzymes are needed to express areas of DNA that cause too much cell proliferation and deactivate normal programmed cell death called apoptosis.
Third, they cause the induction of liver enzymes needed for phase II detoxification. This allows them to be passed out of the body in feces and urine.
So, these powerful chemicals work directly to inhibit the cancer from growing AND help the liver to get rid of the chemicals that can cause cancer in the first place.
Thiocyanates act as antioxidants. They have specifically been shown to have protective effects against peroxide and perchlorates (found in bleach), decreasing inflammation after exposure to exogenous or endogenous causes.
One study found benefit for decreasing lung inflammation in cystic fibrosis patients. Thiocyanates seem to have the ability to inhibit an enzyme that is part of an inflammatory pathway. This inflammation then causes increased mucus production which decreases oxygen flow and creates an environment that allows bacterial growth.
More study on thiocyanates is being done to see what their anti-inflammatory effects are on heart, brain, lung, kidney and other tissues.
Indoles are another class of cruciferous phytonutrients. Indole-3-carbinol (I3C) comes from glucobrassicin. While I3C is itself biologically active, in the stomach it breaks down into several other biologically active molecules such as Di-indolylmethane (DIM), and dihydroindolo-[3,2-b] carbazole (ICZ).
Her are some of the ways indoles have been found to be biologically active in the human body.
Studies have shown I3C and DIM to suppress proliferation rates of cancers such as melanoma, prostate, estrogen sensitive breast cancer cells. The suppression of proliferation encourages apoptosis—a normal programmed cell death.
Indoles also decreased the ability of abnormal cells to migrate and become invasive and decreased to development of new capillaries (angiogenesis) that are needed for cancer tumors for growth.
2. Autoimmunity and Immunity
Lupus, because of its association with estrogen, has shown some improvement in some cases where I3C was given. Current studies are being done to see if I3C supplementation will be an effective treatment for this autoimmune condition.
Indoles also have influence over cell mediated immunity by regulating T-cell populations and RNA-dependent pathways responsible for cell division and/or apoptosis.
3. Estrogen Metabolism and Balance
I3C and DIM affect the metabolism of estrogen pathways. Rather than estradiol being converted to the more active 16-hydroxy estrone, indoles push the conversion to 2-hydroxyestradiol or 4-hydroxyestadiol. These last two metabolites are very weak estrogens and are more water soluble which allows the body to get rid of them in feces and urine.
In men, indoles keep testosterone from being metabolized to estrogen pathways.
4. Viral Infections?
Animal model research on Respiratory papillomatosis, caused by HPV, have shown that severity of disease is lessened with increased cruciferous vegetable consumption.
Women diagnosed with cervical intra-epithelial neoplasia (CIN), also caused by HPV, were given I3C for 12 weeks. Almost 50% of them had no evidence of CIN with the final biopsy.
There’s certainly more research needed on this, but it looks interesting!
Cruciferous vegetables will help to bring a healthy estrogen balance to the body. Here’s how that happens…
Fiber. Diets that are high in fiber set up the conditions for a healthy intestinal environment by supporting good bacteria and by helping the body to eliminate toxins (like estrogen) and other waste from the body.
When estrogens, both endogenous (coming from our own body) and exogenous (coming from outside of the body), get metabolized by the liver, they then get dumped into the intestines. From there, the normal course of events should be elimination from the body.
Fiber does 3 things:
- It absorbs whatever is in the intestines—water, toxins, bacteria, estrogen, etc.—so that it is more difficult to be reabsorbed.
- It provides food (pre-biotics) for the good bacteria (probiotics).
- It keeps the intestines moving so that waste can be eliminated on a daily basis. Yup. Daily.
A high fiber diet will aid the detoxification systems of your body.
If you don’t have a bowel movement daily, you need to fix that.
- Eat plenty of leafy green vegetables.
- Drink plenty of water.
- Add flax seed to your diet.
If you would like to know more about how to use flax seed meal as a fiber supplement, you can read ”Flax Seed for Health in a Ketogenic Diet”.
Hormone metabolism. You can see from the beneficial effects mentioned for each phytonutrient, that many of the benefits seem to be related to decreasing estrogen dominance.
Cruciferous vegetables help the body to metabolize the more active and potent forms of estrogen in both men and women. They are metabolized to forms that are weak and more water soluble, allowing elimination in the urine.
In an article reviewing dietary guidelines for breast cancer patients (Adv.Nutr. 2017 Jul 14;8(4):613-623. doi: 10.3945/an.116.014423. Print 2017 Jul.), the authors state, “Garlic and cruciferous vegetables must also be part of the nutrition therapy”.
Of course, they’re also good for prevention.
Studies consistently show that the fiber and phytonutrients in cruciferous vegetables change intestinal microbiota for healthy bacterial balance. More and more medical professionals recognize the importance of having a healthy intestinal system as foundational for good health—physically, mentally and emotionally.
In a study published in 2013 (Curr.Pharm.Des. 2013;19(1):157-62) authors found that sulforaphane protected intestines from damage by NSAIDs/aspirin and protected against mucosal invasion by enterobacteria.
If you’re concerned about healing intestinal permeability (leaky gut), high fiber cruciferous vegetables are a must.
Cruciferous vegetables have gotten a reputation for being goitrogenic. That is, they are said to cause a goiter in the neck which is a result of the thyroid gland not having enough iodine. Some of the sulfur containing molecules are thought to compete with iodine uptake of that gland.
So, I tried to find any study that would confirm that line of thinking. I couldn’t find one.
A retrospective study done in New Zealand showed that dietary exposure to cruciferous vegetables had “no appreciable risk with a lifetime of exposure”, and “despite several decades of conjecture, there is no evidence to support a causative role for dietary glucosinolates in human goiter”.
A study done on several cancer cell lines used DIM and found “DIM also inhibited the growth of primary goiter cells by 70% compared to untreated controls.”. So, in these cell lines goiter was actually inhibited.
In populations were there is a lot of iodine deficiency, there is the small possibility of goiter becoming a problem when cruciferous vegetables are added. Of course, there would have been that potential in those populations even without brassicas.
A well-rounded plant-based diet will take care of that issue. Try adding some mineral rich seaweed or kelp to your diet and keep on eating those powerful cruciferous vegetables! Eat some cooked. Eat some raw. Put some in a keto-friendly green smoothie. You’re going to learn to love them!
Iodine Rich Foods
- Raw dairy products
- Eggs from pastured hens
- Wild caught Cod and Tuna
- A good sea salt like Sea-90 (but this has a very small amount and can’t be your only source of iodine).
For more detailed information on iodine, read “The Importance of Iodine”.
Roasted Brussel Sprouts Recipe
If you haven’t been very fond of cruciferous vegetables, try roasting them. Add herbs and spices that are full of flavor. Give this recipe a try:
- 1 pound Brussel Sprouts, cleaned, trimmed and quartered
- 1 package mushrooms, cleaned and quartered
- 1 onion chopped
- 1 red sweet pepper
- 2 large garlic cloves, finely minced
- Olive oil, enough to coat the vegetables
- 2 tablespoons fresh thyme (or 1 tablespoon dried)
- Salt and pepper to taste
Mix all the ingredients in a roasting pan. Roast at 350 degrees for 40 to 60 minutes or until nicely caramelized. You may have to stir them once or twice for even roasting.
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