What Are “Superfoods”?
Some may argue that there is no such thing as a superfood. In truth, there is not one single food that can provide you all of your nutrition needs and improve your overall health. Each individual food provides unique health properties, which in combination with an overall healthy eating pattern, can provide significant health benefits and reduce your risk for certain chronic diseases.
A “superfood” is a food that is nutrient dense. This means it is high in beneficial nutrients, vitamins, minerals, fiber, etc., in relation to calories/weight. In addition, a superfood is also exceptionally high in antioxidants and/or phytochemicals. This provides immune and disease fighting protection. If you’d like to know more about antioxidants, I mention them in my blog Top 10 Nutrition Tips On Living A Healthy Life On Dialysis.
How Can These Superfoods Improve Your Kidney Health?
Having chronic kidney disease (especially if you are on dialysis) exposes you to more oxidative stress and inflammation. Oxidative stress can increase your risk for certain diseases like cancer and heart disease(1). Eating a diet rich in antioxidants can help protect you from these risks and boost your immunity.
You will find most superfoods come from plant based sources. There seems to be a significant link between a higher fruit and vegetable intake and a reduction in overall mortality for dialysis patients (2). Eating too much of any of these foods, however, can negatively impact your blood potassium levels. Portion size is key and choosing from a variety of different sources is best to get the most benefit.
The following is a list of kidney friendly superfoods that you can start incorporating into your meal planning to help power up the renal diet!
An apple a day keeps mortality away? This low potassium fruit is packed with polyphenols (naturally occurring antioxidants) and a soluble fiber called pectin. Not only do they improve cardiovascular health but potentially gut health too (3). The antioxidant properties in apples may also lower the risk of certain cancers (4). Keep the peel on for more fiber benefit!
How to include them in your diet: Add chopped apples to your salad, tuna salad, or cook them in your oatmeal. Slice an apple and pair it with unsalted natural peanut butter for a snack (take your phosphorus binder with this). For a tasty treat you can bake or sauté apples with a little butter, brown sugar, cinnamon, and nutmeg and add some Reddi Wip non-dairy whipped cream.
Dark leafy greens are a rich source of vitamin A and vitamin C (natural antioxidants), calcium, magnesium, manganese (a trace mineral), phytochemicals, and fiber! What is great about raw arugula and kale is that that they are low in potassium. One cup will give you approximately 80 mg of potassium. Raw spinach contains around 140 mg of potassium which is an acceptable amount. However, compare that to 1 cup cooked spinach and you get over 1100 mg potassium! Spinach shrinks a lot during cooking, so it is much more densely packed with nutrition. Not the best option for someone trying to limit their daily potassium intake.
How to include arugula/kale in your diet: Salad! Arugula has almost a bitter peppery taste which makes adding something a little sweet like sliced strawberries or blueberries on top a nice addition for balance. Use olive oil and balsamic vinegar as a dressing. You can also add arugula to your sandwiches or 1 cup kale to a stir fry.
Much of the grains we consume today are highly processed and refined. This processing removes some – if not most – of the beneficial nutrients. Ancient grains, as the name implies, have been around for centuries. They are unrefined whole grains packed with nutrients, fiber, antioxidants, and protein . Amaranth, Bulgur, Buckwheat, Kamut (khorasan wheat), Millet, and Quinoa are a few examples. Quinoa is one of the only plant foods to contain all 9 essential amino acids, making it a complete protein. Buckwheat is a gluten-free grain low in phosphorus. Bulgar is also a great lower phosphorus and potassium option.
How to include more ancient grains in your diet:
- Bulgur – A great replacement for rice. Use bulgur in salads, as a side, or cooked along with oats for a hot cereal.
- Buckwheat – Grind up buckwheat groats and cook as a hot cereal or use to make tabbouleh salad. You can use buckwheat flour to make pancakes or waffles. Soba noodles (made from buckwheat) are a fun substitution to regular pasta noodles.
- Quinoa – Substitute for rice, add to salads and soups, or use as a hot breakfast cereal.
Berries are an awesome kidney friendly fruit. Low in potassium (per 1/2 cup serving), they are a good source of fiber, and packed with antioxidants and phytochemicals! Berries are rich in vitamin C and contain bioactive compounds (phenolic acids, flavonoids and tannins). These antioxidant compounds provide a wealth of health benefits including fighting inflammation, protection against cardiovascular diseases, and may reduce the risk of various cancers (5). Each one contains different properties and potential benefits.
- Blueberries – One of the highest sources of antioxidants, particularly anthocyanins. Blueberries provide protection against oxidative damage to your cells, may lower blood pressure and risk of heart disease, provide bone protection, and improve brain function and insulin sensitivity (6).
- Cranberries – Cranberries contain a high level of antioxidants including proanthocyanidins. These particular antioxidants help prevent certain bacteria from sticking to the urinary tract walls which may reduce the occurrence of urinary tract infections and help with gastric ulcers (6). Cranberries may also provide protection against cancer and heart disease (7, 8).
- Strawberries – Strawberries are a good source of manganese (an important trace mineral), fiber, and have one of the highest amounts of vitamin C. They also contain high levels of antioxidants called polyphenols, providing protection against oxidative stress, inflammation, and heart disease. Additionally, strawberries may lower LDL (bad) cholesterol (9).
- Raspberries – Another good source of vitamin C, manganese, B-vitamins, low in carbohydrates and high in fiber. They also are rich in phytochemicals providing protective health benefits.
How to include more berries in your diet: Fresh or frozen, you can add berries to your cereal, salads, pancakes or smoothies, or eat as a snack. Add dried cranberries to salad or oatmeal, sip on low sugar cranberry juice, or make fresh cranberry sauce. Add some non-dairy whipped cream on top strawberries or raspberries for a tasty treat.
Red Bell Peppers
Why red bell pepper and not green you may ask? Good question! Basically, green bell peppers are the unripe version of red, yellow, and orange peppers. Because green peppers are less ripe they don’t taste as sweet as red peppers and also contain fewer nutrients. Red bell peppers contain a lot more beta-carotene and lycopene (carotenoid antioxidants), vitamin A, and vitamin C than green peppers. Carotenoids are powerful antioxidants which may increase your immunity, reduce inflammation, protect eye health, and reduce your risk for cancer and heart disease (10).
How to include more red bell peppers in your diet: Add to salad, stir fries, egg scrambles, kabobs, or slice and dip in hummus for a snack. You can also stuff peppers with fresh ground meat and rice and bake as an entree.
Cabbage is a great kidney friendly cruciferous vegetable that is low in potassium and full of phytochemicals and nutrients. Both green and red cabbage are good sources of fiber, vitamin K (helps increase bone density), and folate. Red cabbage, however contains a lot more vitamin C, vitamin A, iron, and antioxidants than green cabbage. Only red cabbage contains anthocyanins, a powerful antioxidant providing protection against inflammation, cancer, diabetes, heart disease, and other health issues (11, 12).
How to include more cabbage in your diet: make coleslaw or chop and add to salads, soups. Roast cabbage as a side with vinaigrette or add to your tuna salad. I love adding fresh shredded cabbage in my tacos.
Cauliflower is another cruciferous vegetable that is low in potassium and high in vitamin C, folate, vitamin K, choline (an essential nutrient), and fiber. In addition, it is rich in antioxidants and phytochemicals such as carotenoids, flavonoids, glucosinolates, and sulforaphane. These compounds provide anti-inflammatory benefits, boosting immune health and may reduce the risk of heart disease and cancer (13, 14).
How to include more cauliflower in your diet: eat it raw along with red bell peppers dipped in ranch dressing. Roast it with olive oil, garlic, pepper, or curry powder. Cauliflower makes a great substitute for potatoes in potato salad and other potato dishes. It can also be pulsed in a food processor and made into cauliflower rice.
Garlic! One of my favorite flavor enhancing, immune boosting, cholesterol lowering, and breath repelling vegetables. Vegetable? Technically, garlic is considered a vegetable as it grows underground in bulbs and is in the onion (Allium) family. But, since we don’t usually go around snacking on whole garlic, we typically think of it and use it more as a spice or herb.
Most of the health benefits of garlic are attributed to its sulfur containing compounds. Garlic has antimicrobial and antioxidant properties and has long been used to fight colds and infection. Garlic is anti-inflammatory and may reduce the risk of cardiovascular diseases, and certain cancers. (15,16). Besides garlic’s heart healthy benefits, it may also help lower blood sugar and promote the growth of friendly bacteria in the gut, making it a good potential treatment option for chronic kidney disease (17, 18). I can’t wait for more studies on this!
How to include more garlic in your diet: Mince garlic or crush (using a garlic crusher) and add to stir fries, pastas, sauces, salad dressings, roasted vegetables, and different meat dishes. I love dipping sourdough bread in a mixture of olive oil, a little balsamic vinegar, and adding a little crushed raw garlic. Yum. But, if that is too potent for you, you can always roast garlic and add it as a spread.
I know what you’re thinking. There seems to be a trend going on with the red version of a fruit or vegetable being superior. You can blame anthocyanins (an antioxidant) which give them their color! Besides containing more antioxidants, red grapes specifically have more resveratrol (especially in the skin) which is a polyphenol antioxidant that may protect against inflammation, heart disease, cancer, and diabetes (19). Both green and red grapes contain vitamin C, vitamin K, manganese and are a lower potassium fruit making them a good dialysis friendly option.
How to include more grapes in your diet: Eat as a snack, add to salads, chicken salad, or freeze as a thirst quenching treat.
The first elixir in our super “food” list! Green tea is probably one of the healthiest beverages out there with the science to back it up. Green tea is a rich source of catechin antioxidants, including a polyphenol compound called EGCG (epigallocatechin-3-gallate). EGCG is a powerful antioxidant that has been found to potentially reduce the risk of cardiovascular disease, diabetes, certain cancers, Alzheimer’s and Parkinson’s disease, in addition to being anti-inflammatory (20, 21). So, enjoy and sip the benefits responsibly!
Mushrooms are edible fungi that actually taste good! They have been eaten for centuries and widely used for medicinal purposes. Mushrooms are rich in antioxidants (indoles, polyphenols, and carotenoids), selenium (an essential mineral that acts as an antioxidant), B vitamins, zinc, copper, and also contain a decent amount of protein. In addition, mushrooms are one of the few unfortified food sources of vitamin D. The amount of vitamin D is increased with exposure to UV-light or sunlight.
Besides their antioxidant and anti-inflammatory activity, studies have shown that mushrooms can positively impact cancer, diabetes, hyperlipidemia, and can act as a prebiotic to stimulate the growth of healthy bacteria in our gut (22, 23).
How to include more mushrooms in your diet: 1 cup mushrooms contains approximately 223 mg of potassium and 60 mg of phosphorus, so portion size is key. Try sautéing them and adding to stir fries, egg scrambles, rice dishes, or as a side. You can grill them or add to kabobs. Ideally, you want to eat mushrooms cooked to get the full nutrition benefit.
Can a fat be a superfood? Absolutely! Extra virgin olive oil (EVOO) is one of the healthiest fat sources out there and definitely deserves the superfood status. The main fatty acid found in olive oil is oleic acid, a monounsaturated fat. Oleic acid along with oleocanthal (an antioxidant compound) have strong anti-inflammatory effects on the body (24).
Studies have shown that extra virgin olive oil can be heart protective by reducing inflammation, blood pressure, and LDL (bad) cholesterol (25). EVOO may also reduce the risk for type 2 diabetes, and certain cancers (26).
How to include more olive oil in your diet: Extra virgin olive oil should be your staple oil. You can use it for sautéing, stir-frying, grilling, roasting, baking, salad dressings, and sauces. Instead of adding butter to your bread, try dipping it in olive oil mixed with balsamic vinegar!
You wouldn’t think a basic onion would contain much nutrition. In fact, onions are high in vitamin C, vitamin B6, manganese, and contain many health promoting antioxidant compounds. A part of the Allium family (including garlic, shallots, leeks and chives), onions are a major source of two phytonutrients that play a significant role in health: flavonoids (anthocyanins and quercetin) and sulfur-containing compounds.
Red onions, in addition to containing quercetin (a potent anti-inflammatory compound), also have high amounts of anthocyanins which give it its deep purple color. These flavonoid antioxidants and sulfur-containing compounds have anti-bacterial properties and have been linked to fighting certain cancers, heart disease, and diabetes (27, 28). Onions are also a low potassium vegetable making them a good dialysis friendly option!
How to include more onions in your diet: Add sliced onions to your sandwich, bagel and cream cheese, and burger. Chop onions and add to your salad, tacos, fajitas, stir-fries, egg scrambles, rice dishes, and homemade salad dressings.
Unlike most tropical fruits, pineapples are lower in potassium making them a great dialysis friendly fruit. Pineapple contains antioxidants and phytochemicals (29) and is a rich source of vitamin C, calcium, manganese, B vitamins, beta-carotene, and fiber. If you need to limit oxalate in your diet, pineapple is also considered a low oxalate fruit.
In addition, pineapple contains citrate and a digestive enzyme called bromelain which helps break down protein, helps with digestion, and acts as a potent anti-inflammatory (30). Bromelain, in addition to citrate, may help dissolve and pass kidney stones in the body, although more studies are needed in this area (31).
For more fun facts about pineapple check out >> The Pineapple Expressionist! <<
How to include more pineapple in your diet: To get the most benefit from pineapple it is best to eat it raw versus canned. Add chopped pineapple to low salt cottage cheese, stir-fries, kabobs, salad, and if you’re feeling frisky add it as a topping to your homemade low potassium/phosphorus pizza!
Wild salmon, along with other fatty fish such as herring and albacore tuna, are a great source of omega-3 fatty acids (polyunsaturated fats). These health promoting fats are often lacking in our western diet. Omega-3 fatty acids (particularly EPA and DHA) have been shown to be anti-inflammatory and heart protective, lowering triglycerides and LDL (bad) cholesterol, while raising HDL (good) cholesterol (32).
Salmon is also a good source of protein, B vitamins, vitamin A, vitamin D, selenium, zinc, and an antioxidant called astaxanthin. The omega-3 fatty acids found in fish may also prove to be protective against chronic kidney disease (33, 34). Note that salmon does contain a decent amount of potassium: approximately 300-400 mg per 3 oz serving (canned or wild), so be mindful of your portion.
How to include more salmon in your diet: Try grilling or baking salmon. Add canned salmon to your salad or use in place of tuna when making tuna salad.
Turmeric has become a popular spice in recent years, but it has been used in India and Asia for centuries for medicinal purposes in addition to adding flavor in cooking. Turmeric contains compounds called curcuminoids, the most important being curcumin which has powerful anti-inflammatory and antioxidant effects. The curcumin content of turmeric is only around 3% and is poorly absorbed, however the absorption can be enhanced 2,000% when combined with black pepper which contains piperine (35).
Chronic kidney disease (CKD) is an inflammatory disease due to uremic toxins. Interestingly, it appears curcumin increases the expression of the gut enzyme intestinal alkaline phosphatase which helps correct gut permeability (leaky gut). This, in turn, reduces the levels of pro-inflammatory molecules in your blood stream. This might explain why curcumin has potential anti-inflammatory and beneficial effects on CKD despite poor bioavailability (36).
There is actually a randomized clinical trial going on right now looking at the role of curcumin as a nutritional strategy to reduce inflammation, oxidative stress, and cardiovascular risk factors in CKD patients (37). It will be interesting to find out the results!
It’s important to note that most studies used turmeric extracts containing large amounts of curcumin which would be difficult to obtain just adding turmeric to your food. Also, turmeric contains oxalate. Supplemental doses of turmeric can increase urinary oxalate levels, so if you are prone to getting calcium oxalate kidney stones you want to be cautious about using turmeric in supplement form.
How to include more turmeric in your diet: 1 tsp of ground turmeric contains 63 mg of potassium. You can add turmeric to your eggs, salad dressing, tuna salad, rice, cauliflower rice, roasted vegetables, or make turmeric tea or a turmeric latte for a nice warm beverage before bedtime.
Walnuts surpass all other nuts to claim superfood status for a couple of reasons. Not only do they contain one of the highest concentrations of antioxidants, but walnuts are significantly higher in omega-3 fatty acids (alpha-linolenic acid) making it one of the few plant based sources of omega-3s.
Walnuts are also an excellent source of fiber, copper, folate, vitamin B6, manganese, and vitamin E. An additional benefit of walnuts is they may improve gut health. Walnuts have been shown to increase several gut bacteria such as lactobacillus (usually found in probiotics) suggesting they may act as a prebiotic (38).
Like any protein source, walnuts contain potassium and phosphorus so portion size is important. 1 oz (14 halves) contains: 4 g protein, 98 mg phosphorus, 125 mg potassium.
How to include more walnuts in your diet: Eat a portion as a snack along with a piece of fruit (I like to pair it with strawberries). Add to salads, oatmeal, pasta, and stir-fries.
Power Up The Renal Diet!
There are significant health benefits to including these kidney superfoods into your diet. However, eating only a couple of these sources on top of a processed diet or eating any of these foods in large quantities is not the answer. The key is choosing from a variety of these superfoods in the right amounts on top of an overall healthy diet to get the full benefit. Replacing as many processed foods as possible with these whole foods will have a huge impact on your health.
It is usually recommended to eat 5 servings of fruit and vegetables a day (1 serving=1/2 cup or 1 cup lettuce). Try incorporating some of these kidney superfoods into your diet, mix it up, and have fun with it!
Click here for a free pdf download of all the superfoods and how to include them in your diet.