The last time we met, we talked about a few fundamental stuff. For example, what is nutrition? Remember that we said nutrition is the study of nutrients needed for survival, reproduction, and also to make us thrive. As we said, health is more than just the absence of disease but the total well-being of yourself (physical, mental/emotional, and social). We talked about the six basic nutrients that we need to stay healthy. Remember them? They are proteins, carbs, lipids, water, vitamins, and minerals. See if you remember the ones we refer to as macronutrients and the ones we refer to as micronutrients. It’s going to also be important to remember their basic functions. We discovered that beyond nutrients, there are other chemicals in food, namely phytochemicals like certain pigments and flavors that help us combat inflammation and diseases such as cancers. The last thing we talked about was how to determine your nutritional status. In the lab this week we will be testing for a few indices of nutritional health such as blood pressure, pulse rate, muscle strength, and urine composition. Cool stuff. Hope you are looking forward to it.

In this lesson, we’ll discuss nutritional claims and how scientists conduct tests to verify, or make claims. Let me start with this statement for us to contemplate: “Habitual consumption of raw milk reduces the symptoms of COVID-19 infection”, says nutritionist Dr. Paul Goodman. Which of you would agree with this statement? Why, or why not? What sort of questions might be swirling about your mind right now? Here is what I think you might be asking?

  • Who is Dr. Paul Goodman?
  • What’s his qualification? (Blogger, raw milk producer and marketer, academic, lead scientist at the National Institute of Health….?)
  • How did he make this conclusion?
  • If a scientific study, was it peer-reviewed?
  • How consistent is this finding with the scientific community?

I suppose the ultimate question is, can we trust Goodman? You will hear nutrition claims all the time. Some will be so ridiculous you’ll simply laugh and walk away, while others will sound quite believable to make you pause. Let’s assume you were a scientist wanting to test the hypothesis: “Habitual consumption of raw milk reduces the symptoms of Covid-19 infection”. How would you test it? What would be your approach? Two approaches may come to mind. One is doing an observational study, and the other, doing an experimental study.

In an observational study, you are not messing with the subjects, that is you are not directly manipulating them. They are simply observed. For example, you may identify communities that are known for their high consumption of raw milk and access COVID-19 health data that may be publicly available. Their infection rate and symptoms may be compared against a control group that do not consume raw milk.

In an experimental study, instead of simply observing the subjects, you would directly manipulate them by infecting them with a non-lethal concentration of the virus, and then observing symptoms. This is not easy to pull off. Human studies have significant ethical and safety considerations and must be approved through an Institutional Review Board (IRB) or ethics committee. An alternative model is using animals, although this approach still requires review and approval by a review board.

In our lab section of this course, we will be using the experimental approach in answering scientific questions. That means we will be manipulating whatever we are working on instead of just observing from a distance. Regardless of whether or not you use the observational or experimental approach, scientists use the same method to answer questions. It’s called the scientific method.

What is the Scientific Method

The scientific method is a systematic approach to answer scientific questions. It involves at least 7 steps:

  1. Observation: For example, it might have been observed that people in county A who were infected with COVID-19 experienced only mild symptoms compared to the rest of the state.
  2. Questioning: Since country A is known for its high consumption of raw milk compared to the state, the question may be asked, “Does raw milk have a protective effect against COVID-19?
  3. Making a hypothesis: A hypothesis is an intelligent guess as to what you think will happen if you run the experiment, e.g. “Habitual consumption of raw milk reduces the symptoms of COVID-19 infection”. A hypothesis should be testable, and show the relationship between the variables; in this case, the relationship between raw milk consumption and COVID-19 symptoms.
  4. Testing: This is where you do the experiment
  5. Collecting data: Data is collected based on the test. For example, you may report the type of symptoms and seriousness of the symptoms experienced by subjects
  6. Forming a conclusion: Interpreting the data to finalize if it supports the hypothesis. If your hypothesis is not satisfied, this is an opportunity to create a new one and test it again. Perhaps, for example, it was not the raw milk that was producing a protective effect against the Covid-19 virus, but something else unique to that population. What do you think that is? Make a new hypothesis based on your new idea.
  7. Reporting findings: Sharing what you have found. This can be done through an oral presentation, poster presentation, or written peer-reviewed or non-peer-reviewed publication.

Considerations When Running Experimental Studies

Let me take some time to talk about some considerations when conducting experimental studies since you guys will need to come up with a project proposal for an experimental food study in lab.

  1. Variables: Two types of variables in an experimental study that I want you to know are dependent variable and independent variable. Your dependent variable is what you are measuring, while your independent variable is what you are changing. Let’s say, for example, you are testing the effect of temperature on bacterial growth in a food medium. Your dependent variable is bacterial growth. That’s what you are measuring. Your independent variable would be temperature since that is what you will be changing in the experiment to see how it affects bacterial growth. Notice that the bacterial growth is dependent on temperature. Temperature is not dependent on bacterial growth, but independent of it. This should also help you to remember which one is dependent and which one is independent. Here is a mnemonic for you. Remember “I see them” (Jamaicans would say “I see dem” in the patois dialect) or ICDM. “Independent-change” and “dependent-measured”
  2. Procedure: If a standard procedure exists for the experiment you are using, I suggest that you use it. You may find that you may have to make slight modifications to the standard procedure to make it work for you. That’s OK. Just make sure you record and report the modifications. A standard procedure may not exist, but procedures have been developed and used by others in the past. If so, don’t reinvent the wheel if you don’t have to. Just follow what others have. If a procedure does not exist at all, you may need to develop your own. Just remember to test and retest the procedure to make sure that it produces repeatable data before running the full experiment. If you are using a new procedure, even though a standard one exists, make sure you compare the values with those obtained from the standard procedure to check that the procedure produces accurate results.
  3. Testing: During testing, make sure to follow your procedure consistently. Experiments should be repeated to ensure repeatability of the data. The more variation you get in the data, the more repetitions that you will need to do to improve confidence.
  4. Recording: Keep a lab manual to record all your procedures, observations, and thoughts. Make sure that each entry is date stamped. Write legibly. Remember that if you are working at an institution such as a university, or place of business, you do not own the lab book, it belongs to the institution. It is best to keep a backup of your work in digital form just in case your lab book is ever lost.
  5. Organizing your data: Data are generally organized in tables or graphs. Think about who you plan to communicate your findings with and ask the question, “what would be the best way to illustrate this data?'” There is no need to present the same data in different formats.
  6. Presenting by poster: A poster presentation is what it sounds like; a poster with a summary of your research. I use PowerPoint to create my posters (I will provide you with a template later). Essentially you will summarize your research and put it all in a single PowerPoint. After that, the PowerPoint is printed as a poster. A size of 36 inches x 48 inches (91 cm x 122 cm) is common at scientific conferences.

Brainstorm Activity

Get in teams and brainstorm ideas on what you could do for your research project this semester. Write your ideas in the form of a hypothesis statement. Make sure that the hypothesis is clear, testable, and shows the relationship between the variables. Also, make sure that the expected outcome will contribute to new knowledge. Here are three examples of hypothesis statements from past student projects:

  1. Soaking steak in pineapple juice prior to grilling will increase its tenderness
  2. Organic bananas are more flavorful than traditionally grown bananas
  3. Depriving bananas of oxygen during storage will slow down ripening

Wrapping Things Up

Don’t believe any nutritional claim you here without asking critical questions. Scientists test claims using observational and experimental studies and they do so using the scientific method. This systematic process involves observation, questioning, forming a hypothesis, testing, collecting data, forming a conclusion, and reporting.


  • Courtney Simons

    Dr. Courtney Simons has served as a food science researcher and educator for over a decade. He holds a Bachelor of Science in Food Science and a Ph.D. in Cereal Science from North Dakota State University.