Food Combinations: Does This Ayurveda-Inspired Diet Actually Work?

Registered Dietitian Nutritionist By Molly Knudsen, M.S., RDN
Registered Dietitian Nutritionist
Molly Knudsen, M.S., RDN is a Registered Dietician Nutritionist with a bachelor’s degree in nutrition from Texas Christian University and a master’s in nutrition interventions, communication, and behavior change from Tufts University. She lives in the Greater Boston Area, and enjoys connecting people to the food they eat and how it influences health and wellbeing.

Image by LightFieldStudios / iStock

Is it best to eat fruit separately or with a meal? Is eating carbs and protein at the same time hurting your digestive tract? Can certain foods improve the efficiency of your digestive system?

These are just a few questions that the principles of "food combining" aim to answer. Here, we dig into whether or not this Ayurveda-inspired way of eating has real perks.

So, what exactly is "food combining"? 

Food combining theory is based on the belief that eating certain foods together at the same meal can improve digestion and boost the absorption of nutrients. It also implies that the improper pairing of foods during a meal can lead to gas and bloating.

The practice of food combining stems from Ayurveda, a traditional system of medicine originating from India. Diet and food play an integral role in Ayurvedic living, and there is a large emphasis placed on the digestive capacity of each person. According to Ayurveda, each food is characterized based on taste, potency, post digestive effect, and other unexplained effects. When foods with differing characteristics are eaten together, it's said that toxins can form in the body, but that those same foods can be more easily digested when eaten separately.

The basic concept of food combining was then revived in the 1920s through the Hay Diet. The Hay diet was formulated by the New York-based physician William Howard Hay and classifies foods as acid, alkaline, or neutral. He believed that the proper combination of these foods was the solution to improved health. For example, one of Dr. Hay’s rules is that carbs should not be eaten at the same meal as fruits or protein, but should be eaten with neutral foods like fats.  

Skip forward to today, and the food combining diet has made another comeback on Pinterest, with loads of bloggers and influencers sharing their food combining charts and simple recipes. The modern food combining diet seems to be a hybrid of both the Hay Diet and the traditional eating practices of Ayurveda.

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The basic food combining categories.

The rules for food combining diets are grounded in assigning all foods into categories. The typical categories are proteins, starches (or carbs), fruits, low- and non-starchy vegetables, and fats.

1. Fruits

This category includes all that yummy produce we typically think of as fruit. The traditional Hay diet further breaks it down to four sub-categories.

  • Acid Fruits: Citrus fruits (oranges, grapefruit, etc) , pineapples, and tomatoes
  • Sub-acid fruits: Apples apricots, berries, grapes, kiwi, peaches, pears, and plums
  • Sweet fruits: Bananas, coconuts, and dried fruits
  • Melons: Cantaloupe, honeydew, watermelon
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2. Protein

Beef, chicken, fish eggs, legumes, nuts, seeds, and soy products

3. Low- and non-starchy vegetables

Artichokes, asparagus, Brussels sprouts, broccoli, cabbage, cauliflower, celery, cucumber, eggplant, leafy greens, mushrooms, onions, peppers, and zucchini

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4. Starches and carbs

Breads, pastas, grains/cereals, potatoes and sweet potatoes, pumpkin and winter squash (butternut, acorn squash, spaghetti squash, etc) 

The basic food combining rules.

Based on these groupings, these are the basic rules of food combining diets (although rules may vary slightly depending on the source). 

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Foods that can be eaten together:

  • Starches + non-starchy vegetables
  • Protein + non-starchy vegetables

Foods that shouldn't be eaten together:

  • Starches and protein
  • Protein and other proteins
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Foods that should be eaten separately:

  • Fruits (especially melons): at least 20 minutes before a meal or on an empty stomach
  • Dairy foods, including cow's milk

These rules are believed to promote optimal digestion in two ways. First, these combinations pair foods with similar digestion times. Eating foods with different digestion speeds (say an apple, a chicken breast, and brown rice) can overload your digestive system and make it less efficient. 

Second, it is believed that different foods are broken down more efficiently at different levels of acidity (aka pH levels) in your body. So the reason that starches can be eaten with non-starchy vegetables is that both of these foods can be digested at the same pH level, and starches and protein shouldn’t be eaten together because they require different pH levels for digestion.  

What does a day on a "food combining" diet look like?

Here's a sample day-in-the-life on a food combining style diet.

  • Start your morning off with a serving of fruit such as a banana, a bowl of berries, or a grapefruit.
  • About an hour after that, you can have your first official meal of the day. This could be a slice or two of avocado toast on whole grain bread, or scrambled eggs with veggies. (But remember: no cheese on your eggs, because proteins don’t mix and dairy should be eaten separately!) This meal should be hefty enough to get you to lunch without any hunger pains.
  • Lunch could be a salad loaded with fresh veggies and a chicken breast or some tofu for protein. It’s alright to use a salad dressing like oil and vinegar here.
  • Next up is an afternoon snack. This would be another great time of day to get a serving of fruit such as an apple or orange, but leave plenty of time before dinner.
  • For dinner try making a vegetable curry with brown rice.

Is there any scientific evidence to support food combining?

There is really no scientific evidence showing that food combining diets are beneficial for health. In fact, some food combining rules go against what we know to be true about digestion in the human body.

For example, many registered dietitians recommend eating fruits with protein and/or fat to help balance the rise in blood sugar. This is especially important for people with diabetes. Eating fruit with protein or fat helps make that snack more satiating as well. I don't know anyone who’s felt full after eating just grapes!

Additionally, the rules of food combining diets focus on pairing foods with compatible pH levels to make digestion more efficient. But basic biochemistry shows that the body has its own methods to handle the differing pH levels of foods and ensure appropriate digestion.

Digestion begins in the mouth, for starches, and then continues in the stomach. The stomach is an acidic environment due to hydrochloric acid. No matter what you eat, food in the stomach will be acidic. Some proteins are able to be digested in the stomach, but most digestion and absorption happens in the small intestine. The acidic, partially broken down food from the stomach then travels to the small intestine. Once the food enters the small intestine, a hormone called secretin that stimulates the release of pancreatic bicarbonate to make the small intestine more alkaline and less acidic. Most nutrients best absorbed in this less acidic environment.  

Food combining is a way of eating that has been around for thousands of years, and although scientific evidence supporting this diet is lacking, it doesn’t mean it’s not beneficial. The principles of food combining found in Ayurveda are not based on biochemistry, but rather spirituality. Traditional Ayurvedic diets also place a high emphasis on mindfulness when eating. Eating foods in the separate groups, as you would with food combining, may help you think through your food choices and how much of a food you are putting in your body.

Additionally, the rules of food combining don’t always allow for a lot of variety in the diet. Some studies have shown that having more variety in the types of food you eat can cause increased consumption at that meal, and having less variety of foods at meals could help reduce energy intake and promote weight loss. However, that's not necessarily a perk, as this decreased variety of foods may also decrease the variety of nutrients you're consuming.

Are there any foods that actually are better together, based on science?

Looking beyond the Ayurvedic-inspired food combining theory, there are some scientifically proven, synergistic food combinations that should be eaten together to boost absorption of certain nutrients.

1. Veggies + fat

Brightly colored vegetables often contain the fat-soluble vitamins A,D,E, or K that are best absorbed by the body when fat-containing foods are also present. Examples of veggies that are high in these fat-soluble vitamins: squash, kale, sweet potatoes, carrots, asparagus broccoli, and spinach. Try roasting these veggies in olive oil, serving in a salad with avocado dressing, or dipping in hummus to reap the most benefits.

2. Black pepper + turmeric

Curcumin is the main active component of turmeric that contributes to the spice's anti-inflammatory properties. Curcumin is not naturally well absorbed by the body. But, when turmeric is consumed with black pepper, the bioavailability (or the amount of curcumin that can be absorbed by the body) can increase by 2,000%. Golden milk is a great way to try this combo.

3. Vitamin C-rich foods + plant-based sources of iron

Iron that is found in non-animal sources, such as leafy greens, legumes, brown rice, and oatmeal isn’t as readily absorbed by the body as iron from animal-based foods. However, eating these foods with vitamin C can increase absorption. For example, try eating a spinach salad with a lemon vinaigrette dressing.

So, should you try a food combining diet?

Food combining diets are not based on modern nutritional science, but rather ancient theories on how food works together—and so, the rules of food combining may seem unnecessarily complicated. But if you feel like this diet works for you and you like the structure of the rules, it’s not going to cause you any harm either! Just make sure you try to prioritize variety as much as possible, even within the confines of the somewhat restrictive food combining rules, to ensure you're getting in plenty of nutrients.

Ready to learn more about how to unlock the power of food to heal your body, prevent disease & achieve optimal health? Register now for our FREE web class with nutrition expert Kelly LeVeque.

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