Eric Garza

Musings on food, energy and adaptation

Investing in Nutrient Dense Food: Vitamin A

Some years back I read with fascination the book Nutrition and Physical Degeneration. Originally published in the 1940s, the book followed dentist Weston A. Price to distant lands as he searched for the dietary secrets that gave some isolated, traditional societies their comparatively healthy teeth and robust health. One takeaway from the book for me was how much more nutrient dense the diets of some traditional peoples were, and how far from this ideal the eating patterns of many in developed countries have become.

I touched on the health consequences of relying on poor quality foods in Treating Food as an Investment, and have long been an advocate of eating nutrient dense foods. The challenge, of course, is convincing people that nutrient dense foods are affordable, as most people think in terms of cost per pound rather than cost per calorie, an issue I noted in my previous post Making Good Food Affordable. I readily acknowledge that there’s more to the idea of nutrient density than calorie content, so this post will be the first in a series that looks at other nutritional elements of food, beginning with Vitamin A.

What is commonly known as ‘Vitamin A’ is not really a single chemical compound, but rather a suite of fat soluble compounds that include retinol, retinal, retinoic acid and retinyl esters [1]. These compounds play important roles in immune function, reproduction, cell growth, cell differentiation and cellular communication, and play a pivotal role in vision by contributing to the structure of the protein rhodopsin, which absorbs light in our eyes. Pre-formed Vitamin A comes exclusively from animal foods, including dairy products, meat and organs, although our bodies can convert some caroteniod pigments from plants, among them β-carotene, into the vitamin at low efficiencies. Since retinol is one of the primary forms of Vitamin A, the nutrient is typically measured in micrograms of retinol activity equivalents (μg RAE). The US Recommended Daily Allowance of this vitamin varies according to age and sex, with women who are pregnant or breast feeding requiring more while children require less. I’ve presented the cost of meeting a daily allowance of 900 μg RAE from several foods in the graph below, with the Vitamin A content of foods taken from the US Department of Agriculture’s National Nutrient Database and food prices noted at my local farmers’ markets and grocery cooperative [2]. The prices are for pasture raised livestock and certified organic fruits and vegetables.

Vitamin A Liver is by far the cheapest means of meeting a daily allowance of 900 μg RAE of Vitamin A, costing the consumer only eight cents per day. Eggs offer a modestly priced source of Vitamin A, but beyond this the cost of meeting a daily allowance rises rapidly. Sweet potato, kale and spinach are also fairly cost effective sources, although these are plant foods that provide only precursor carotenoid pigments and as any researcher in the field of carotenoid bioavailability and conversion will attest our understanding of how these pigments are converted into Vitamin A remains in its infancy. I recorded data on Vitamin A content for plant foods as presented by the US Department of Agriculture, but I’m not confident that it accurately represents how much actual Vitamin A the average person can get from the plant foods listed in the graph above.

Our body’s capacity to turn carotenoid precursors into Vitamin A depends on a range of factors, and in the best of circumstances this conversion happens at low efficiency. Among the many factors are the species of the carotenoid pigment, the matrix in which the pigment exists in the plant, how much of it we eat in a meal, nutrient status of the consumer and the consumer’s genetics [3, 4]. To make one unit of retinol, which we could easily absorb and utilize from animal foods like liver, most people need to eat 12 units of β-carotene or 24 units of α-carotene or β-cryptoxanthin, although the absorption and conversion of these latter caroteniod pigments can vary tremendously.

Vitamin A was one of three compounds that Weston A. Price identified as hugely important for the health of the traditional peoples he studied, and I suspect it’s a vitamin that many in modern societies face deficiencies in. Most of the societies Price studied had ‘sacred foods’ that were used to nourish growing children and expectant mothers, and these foods were commonly of animal origin and almost universally were prime sources of Vitamin A. I’ve definitely been working to incorporate more Vitamin A rich foods, particularly those of animal origin, in my diet over the past few years, and suspect most would benefit from doing the same. The next of Price’s “Big Three” nutrients is Vitamin D, and I’ll focus on this important compound in my next post.

Notes

  1. Vitamin A: Fact Sheet for Health Professionals. United States Department of Health and Human Services, US National Institutes of Health.
  2. National Nutrient Database for Standard Reference. United States Department of Agriculture, Agricultural Research Service.
  3. J. Castenmiller & C. West (1998) Bioavailability and bioconversion of carotenoids. Annual Reviews of Nutrition, Vol. 18, Pgs. 19-38.
  4. K-J. Yeum & R. Russell (2002) Carotenoid bioavailability and bioconversion. Annual Reviews of Nutrition, Vol. 22, Pgs. 483-504.

Making Good Food Affordable

In Treating Food as an Investment, I note the relationship between reduced food expenditures in the United States over the past several decades and rising healthcare spending. There are many reasons for this relationship, but among them is the fact that most Americans buy very low quality food, a habit that harms our health on many levels. I’m well aware that many people throughout the US face challenging financial situations, which begs the question: Can we afford to buy higher quality food?

While there are certainly differences in cost between high and low quality foods, I don’t think those differences are always as stark as many believe. Part of what drives food price perceptions is that many people think in terms of dollars per pound of food rather than dollars per kilocalorie, and its the kilocalories – the food energy – that actually powers our metabolism. The graph below shows the cost per 100 kilocalories for several types of high quality food at my local farmers’ market and grocery cooperative, and I include the McDonalds hamburger to offer a sense for the cost of cheap, highly processed food [1].

FoodCosts

McDonalds and other fast food companies are well known for producing some of the cheapest calories money can buy in the developed world, so seeing the McDonalds hamburger at the far left shouldn’t surprise anyone. Beef liver, perhaps one of the most nutrient dense foods in existence, is darn near as cheap though, and the price used for these calculations is what I pay for high quality grass fed liver, not cheap liver from animals raised in confined feedlots. Calorie dense root vegetables like potatoes and sweet potatoes are also fairly inexpensive on a per-calorie basis, as are eggs from pastured chickens fed GMO-free grain and 100 percent grass fed ground beef. To the right of these foods we surpass $1 per 100 kilocalories, an arbitrary threshold to be sure but one that certainly drives up the daily cost of food. What might surprise many is that common organic vegetables like broccoli, spinach and lettuce, as well as common fruits like organic applies, oranges and blueberries (which are in season in Vermont right now) are towards the upper end of the price scale, making them comparative luxury items relative to other foods that are inexpensive yet nourishing enough to serve as dietary staples.

On a per-pound basis meat and eggs tend to cost more than vegetables and fruit, especially high quality grass fed meats and pastured eggs, and this higher price per pound causes people to shy away from them. This is unfortunate since the price differential is negated by animal foods’ higher calorie density, so that costs per calorie for meat and eggs are usually equal to or lower than that of most fruits and vegetables. High quality animal foods will probably never beat a McDonalds hamburger, but organs like liver – which are far more nutritious than pricier cuts of steak and tenderloin anyway – come very close.

When investors look across a range of possible investment opportunities, they don’t choose at random. They do their homework, and only after thoroughly researching their options do they make decisions on where to invest their money. I’m always stunned at how uninformed many people are regarding the nutritional benefits (and costs) of the food they buy and eat. This lack of information prompts many people to make poor decisions on how they invest their money when buying food, leading to food costs that are far higher than necessary and that still don’t provide a balanced diet. The trick to making better food investment decisions is to learn about the food you’re buying, so that when you visit the farmers’ market or grocery store you can shop wisely.

Surely many who read this are crying foul, exclaiming with ferocity that food is more than just calories. They’re right of course. This post marks the first of a series that will explore the broader issue of getting the most for our food dollars, and my next post will look at the cost per unit of vitamins and minerals for many of the same foods I’ve studied here. I expect this investigation to offer further insight in the particulars of enjoying reasonably priced, nutrient dense diets that are nourishing on many levels.

Notes

  1. By “high quality” I mean that all produce is certified organic, all pork, poultry and eggs are pasture raised, and all beef is 100 percent grass fed. Calorie densities are from the US Department of Agriculture’s National Nutrient Database.

 

The Art of Fermentation

In The Energy Cost of Food I note that household energy use associated with food sourcing, preservation, processing and preparation represents about a quarter of total food system energy use. Since consumers have the most control over energy used in their homes it makes sense to ponder how to reduce it, if for no other reason than to save money on utility bills and to create a buffer against the agonies associated with power outages. One way to reduce household energy use associated with food is to adopt fermentation as a primary means of food preservation. The process of fermentation involves allowing particular types of bacteria to digest the sugars in foods, releasing lactic acid as a waste product that acidifies the food and prevents spoilage.

KatzGarzaSandor Ellix Katz, who wrote Wild Fermentation over a decade ago and The Art of Fermentation more recently, is a leader in the resurgence of fermentation and I had the pleasure of attending a two day workshop with him at Shelburne Farms over the past two days. While I already knew the basics of the process, the workshop opened up several new doors for inquiry and also gave me a chance to mingle with over a hundred other people from Vermont and surrounding states who shared my interest in food and traditional health.

The first day of the workshop focused on fermenting fruits and vegetables, and after lunch the 100 or so attendees chopped vegetables to fill a jar to ferment at home. I’ve done this 100 times, but for many people this was their first experience preparing vegetables to ferment so it was fun interacting with people and listening to the questions that cropped up. For this recipe we chopped a mixture of cabbage, radishes, turnips, carrots, onions, garlic and perhaps a few other things, and while mixtures of vegetable ferment taste reasonable to me I prefer ferments that focus on one or at most a few vegetables, so I elected not to fill a jar and let others take a bit more.

The second day of the workshop was more varied; Sandor started the morning lecturing on different types of dairy ferments, including making yogurt, kefir and ending with a brief discussion of cheese. I was intrigued to learn that commercially available kefir isn’t really kefir. Traditional kefir typically has an alcohol content around 1 percent, but given modern food laws this would have to be marketed as an alcoholic beverage so commercial producers adjusted the microbial cultures to constrain the alcohol production. The result is something vaguely like traditional kefir, but it isn’t really kefir, but people want kefir so this label is used even though it isn’t accurate. The final segment of the workshop detailed with grain and legume fermentation, which I’m admittedly not interested in, as well as a brief discussion on fermenting meats.

While I introduced fermentation as a means of low-energy food preservation, it does so much more. Fermentation, particularly of plant foods such as fruits, vegetables and grains, serves to predigest the food and break down nutrient complexes to make nutrients – particularly minerals - far more bioavailable. Another service fermentation provides is detoxification; some anti-nutrients and other toxins in foods can be broken down during the fermentation process, making the food not only more palatable but also less likely to cause harm when eaten. A final benefit of fermentation that complements these earlier two benefits is nutrient enhancement. The microbial action inherent in the fermentative process creates nutrients in foods that weren’t present or were present in much lower quantities, among them B vitamins, certain antioxidants and some short-chain fatty acids.

In all fairness, I do want to warn against eating too much fermented foods. They are quite acidic, with pH values commonly below 3 or 4, so if eaten too frequently or in large helpings the acid can degrade tooth enamel much like constantly slugging soda or vinegar. Eaten in small quantities though, these foods’ acidity shouldn’t cause too much of a problem and they certainly offer a range of benefits. Indulging in fermented foods to excess without any prior experience with them can also cause stomach or intestinal upset for some people, so a relationship with fermented foods is best started slowly. Despite these cautions, I certainly enjoy eating fermented foods on a regular basis and experiment with making them myself to cut costs, and encourage others to do the same.