So what’s the story with protein? Over the last 20 years, we’ve gotten a lot of mixed information about how much and what kinds of protein to eat. Should you go vegetarian or paleo? Was Atkins right? Or should you stay away from animal protein altogether?

The truth about protein is actually more nuanced than either camp would have you believe. Each person is different and thrives on different types of food. Some do fantastic as vegans, others wither. Some thrive on animal protein, some are sluggish and sick.

Whether you focus on vegetarian sources or animal sources, one thing is certain: Protein is an essential part of the human diet.

ALL of the thousands of molecules in your body are built from only 8 essential amino acids that we must get from our diet. These essential amino acids are the raw materials out of which our entire body is constructed. Here’s how it works.

When it is digested, the protein you eat is broken down into its constituent elements: amino acids. The only job your DNA does is take these amino acids and build them into strings of proteins that make up every molecule and every cell in your entire body. That’s ALL it does! Think for a moment about what happens when you don’t get enough dietary protein. Your DNA has nothing to work with. This is a tremendous problem.

But the importance of protein doesn’t end there.

Protein makes up all of our messenger chemicals or neurotransmitters that do the “talking” in your brain and throughout your body. Protein is also used to build the little receptors or docking stations for these neurotransmitters that are embedded in your cell membranes. So if your cells are going to “talk” to one another or if they are going to “hear” anything at all, they need protein to help them do it. Without protein the vital communication your body depends on is silenced.

The ONLY source of these amino acids is the protein you eat in your diet.

If you don’t eat adequate protein at every meal, your body and brain can’t work. You will be sluggish, foggy, anxious, unfocused, tired, and depressed. You will also get hungry. Protein helps balance the glycemic load of your meals and mitigates hunger. This means you will tend to eat more throughout the day if you eat too little protein at each meal. This can lead to weight gain and all of the problems that come along with it.

So there is no question about the importance of protein in your diet. The real questions are how much and what kinds of protein to eat.

How Much Good quality protein should make up 25 percent of your plate. One serving is about 4 to 6 ounces or about the size of your palm.

Some few may thrive on a diet heavy in rich animal protein—like red meat. But most of us need to be careful. Research, including T. Colin Campbell’s China Study, points to the risks of too much animal protein.

Therefore I recommend you choose from these high quality safe sources of protein and include them at every meal:

Beans or legumes: You can soak them overnight or used canned beans for a quick way to add protein to soups, salads, or stews. There are so many varieties to try—chickpeas, adzuki, Anasazi, mung, kidney, black, or pinto beans—are good options.

Nuts: (almonds, walnuts, macadamia nuts, pecans) Nuts are full of protein and can help satisfy your appetite.

Seeds: (pumpkin, sunflower, flax, chia, etc.) Seeds are an easy way to power up on protein. Add them to smoothies or salads!

Eggs: Omega-3 or free-range is best.

Fish: Wild-caught, smaller fish that are toxin free are the way to go. Think sardines, tilapia, crawfish, and fresh-water trout for good sources of protein and omega 3 fats.

Poultry: Choose organic, grass-fed, hormone-, antibiotic-, and pesticide-free. Turkey and chicken are easy on your budget too!

Soy: Stick with traditional whole soy products. These include tempeh, tofu, miso, and natto. Avoid processed soy products.

Small amounts of lean, organic grass-fed, hormone-, and antibiotic-free lamb, beef, buffalo, ostrich, and others (buffalo, venison and ostrich are leaner). Eat red meat no more than once or twice a week and no more than 4-6 ounces per serving.

By adding these types of protein to every meal you will stabilize your appetite and provide your DNA the fuel it needs for building your body and brain.

Remember, protein is power—the power of lifelong health and a stable, calm, happy mind.