All bodies naturally have odors. A wide variety of factors contribute to these odors, including genetic predispositions, lifestyle, hygiene, and overall state of health. Additionally, several research studies suggest that overactive sweat glands may be responsible for unwanted body odors in some individuals. Diet is definitely an additional factor that can contribute to body odors. There are very few research studies, however, that have examined the impact of diet on body odor from a science-based perspective.
An area of research you're sure to be reading more about in the future involves the role of high-methyl foods and body odor. High-methyl foods (those that support the metabolism of methyl-group containing compounds) can be broken down in the digestive tract to create a compound called TMA (trimethylamine). This compound can be excreted through the breath, urine, and sweat and is associated with a problem called "fish odor syndrome." Soy foods, beets, and spinach would all be considered "high-methyl" foods since they are rich in methyl-containing nutrients like choline, betaine, and lecithin. I cannot imagine, however, trying to solve any body odor problems related to high-methyl foods by removing those foods from your diet! Methyl-containing foods are critical for your health and especially important in your body's ability to detoxify unwanted substances like heavy metals, pesticide residues, or synthetic food additives. Instead, if you suspect that a potential connection between your consumption of high-methyl foods and any body odor issues (specifically those that may be described as having a "fish odor"), I recommend that you let a healthcare professional evaluate the health of your digestive tract and other body systems and try to determine whether you might benefit from dietary changes or other steps.
In principle, the most natural body odor should come from a body that is in its optimally healthy and most natural state. I believe that a whole, natural foods diet consisting of minimally processed, organically-grown foods produces optimal nourishment. I also believe that each person's Healthiest Way of Eating should be individualized. A person's health history and current health status are important considerations in this regard as is a way of eating that produces no adverse food reactions. If foods are not matched to a person's metabolism, it's unreasonable to expect those foods to support vitality and good health. Without vitality and good health, it seems equally unreasonable to expect natural body odor.
I've been asked about the possibility of body odor problems due to high dairy intake. If there was scientific research on dairy products and body odor (there isn't any), I would not expect that research to show that dairy products produced unwanted body odor. Instead, I would expect a mixture of findings. For individuals well-matched to dairy products, with no allergic reactions or lactose intolerance, who consumed moderate dairy intake, I would expect perfectly acceptable body odor provided that the overall diet were balanced and nourishing. For individuals poorly matched to dairy products, including those who have lactose intolerance or allergic reactions (or those who have excessive dairy intake), I would expect a much more common finding of unwanted body odor. Individuals falling somewhere in between would be expected to have unwanted body odors some of the time, but in a less predictable way.
Remember that your body is always striving for optimal health and trying to eliminate all substances that might compromise your wellness. For this reason, unwanted body odors can sometimes be regarded as a natural process in your body's elimination process, and not a reason for dietary, behavioral, or lifestyle change. However, routine body odors that seem offensive are most likely pointing in the direction of a needed change. If the needed change is dietary, I recommend consideration of your overall way of eating, with an emphasis on possible adverse food reactions, allergies, and intolerances. There should also be a focus on overall dietary balance, including food excesses, macronutrient excesses (such as too much fat or too many simple sugars), caloric excesses, and nutrient deficiencies.