The Limitations of Nutritional Studies

This article does a decent job summing up why it’s difficult to conduct good nutritional research.

  1. It’s not practical to run randomized trials for most big nutrition questions.
  2. Instead, nutrition researchers have to rely on observational studies — which are rife with uncertainty.
  3. Another difficulty: Many nutrition studies rely on (wildly imprecise) food surveys.
  4. More complications: People and food are diverse.
  5. Conflict of interest is a huge problem in nutrition research.
  6. Even with all those faults, nutrition science isn’t futile.

When it comes to deciding what to feed Nora, I want to take an evidence-based approach, but focusing solely on randomized trials completely misses the forest for the trees. So there’s good reason to look to food culture and food traditions instead.


Veggies, Fiber, Sleep Quality, and a Healthy Immune System

I love Paleo Mom. She’s a scientist who never fails to substantiate her claims and make research accessible to the masses. In the blog post below, she talks about new research that suggests that eating more fiber improves sleep quality.

And here, she talks about why veggies are important for gut health and a healthy immune system.

Much as my blog is about incorporating fat, seafood, and offal into Nora’s diet, my first love is still veggies.

Saturated Fat

As always, Paleo Mom brings claims about saturated fat back to earth. Even though the link between saturated fat and heart disease is mostly bunk (though not for everyone), going overboard on saturated fat carries other health risks. Moderation is best.

While eating excessive amounts of saturated fat doesn’t seem to be a good idea, eating too little saturated fat could also be a problem. Why? Well, when we cut way back on saturated fat, we have to either replace those calories with other forms of fat (monounsaturated and polyunsaturated (PUFA)), or we have to eat a diet low in total fat (and fill in the rest with carbohydrates and protein).

Although monounsaturated fats are pretty neutral, we run into problems when increasing our PUFA intake (especially in the form of omega-6 fatty acids). Polyunsaturated fats have very delicate, fragile structures that are prone to oxidizing. Although they do play an important role in health when eaten in proper quantities, excessive amounts can be harmful: the PUFAs we eat become incorporated into our cell membranes and can increase our risk of free radical damage (leading to a cascade of problems such as higher cancer risk and higher risk of heart disease!). Omega-6 PUFAs in particular tend to be pro-inflammatory, especially if they’re not adequately balanced by omega-3s. So, if we try to avoid saturated fat and simply replace it with PUFAs, we’re creating a macronutrient profile with a new set of problems!

The other option, eating a diet low in total fat, isn’t a great strategy either. While there are definitely some vocal proponents of low-fat diets out there (such as Dean Ornish), the bulk of the available evidence points to low-fat diets having plenty of risks! For one, we need some dietary fat to optimize the absorption of the fat-soluble vitamins A, D, E, and K (which are critical to tons of processes in our bodies). Also, low-fat diets and having low levels of serum cholesterol (which tend to go hand-in-hand) have been linked to a variety of health conditions, including depression and suicide (low-fat diets may impair serotonin receptors by decreasing the fats in nerve-cell membranes), anxiety, aggression, other violent behavior, premature death, and even cancer (fat and cholesterol are important for the integrity of cell membranes).

Overall, the research points towards a moderate fat intake (30-40% of calories, perhaps as high as 50% for some people) and moderate saturated fat intake (10-20% of calories) being ideal for maintaining all aspects of our health.

Vegetarian Research

I need to track down citations for this, but my very specific reasons for avoiding feeding Nora a strictly vegetarian diet boils down to the fact that we as individuals metabolize food differently and not everyone is equally efficient at the following conversions:

  • Carotenes to Retinol (Vitamin A)
  • ALA to DHA and EPA (Omega-3s)
  • Vitamin K1 to Vitamin K2

As far as I can tell, Jeremy and I did fine on a vegetarian diet. We certainly ate plenty of veggies containing carotenes and Vitamin K1.

I’d like to find studies comparing vegetarian and vegan kids with omnivorous kids, but I’d expect that to be clouded by various other factors, namely unhealthy diets in all camps. I don’t doubt that vegetarian kids might be healthier than kids that don’t eat any vegetables, but to me, that’s not saying much.

Also, I can’t imagine that I’d find a study that tackles bone and eye health or answers the question, are optimally fed vegetarian kids more likely to need glasses and braces than optimally fed omnivores?

Oats, Revisited

Various sources say that soaking alone is not enough to reduce phytates in oatmeal. The Nourishing Home recommends adding some other grains with higher phytase content.

The one exception to the above soaking rule is oats. Oats contain a large amount of hard-to-digest phytates and other anti-nutrients. Unfortunately oats are so low in phytase (the enzyme that helps to break down phytates), that soaking them in warm water mixed with an acid medium is not enough to adequately break down the large amount of anti-nutrients that naturally occur.

However, with the help of some additional phytase added to the soak (in the form of rolled rye flakes, or if you’re GF use ground buckwheat groats – both are high in phytase) – along with a full 24-hour soak time – a fairly decent amount of the anti-nutrients can be removed, making the oats more digestible and nutritionally sound.

Here is her recipe for oatmeal:

Why Eat Veggies

Nora is not always the biggest fan of veggies. She’ll eat them as long as they’re nice and soft and mixed with avocado, yogurt, or eggs, but she just doesn’t get excited the way she does with fish or meat. Which left me wondering: why are veggies so important and why do we push them so hard? I knew about all the vitamins they contain, but I just learned from Paleo Mom about their importance in the acid-base balance of the body.

At the level of kidney filtration, some foods are acidic and some are alkaline. Extra acid is passed into the urine, but if the body is lacking in alkaline foods, it will use extra calcium from your bones to process the acid.

Basically all fruits and veggies are alkaline. Eggs are effectively neutral. Nuts and seeds are a mixed bag, with some being alkaline and some (especially the high omega-6 ones) being neutral. Meat, poultry, fish, shellfish, grains, legumes, dairy, modern vegetable oils, and salt are all acidic.

Consuming vegetables is still an important way to protect your bones  and your kidneys, while also providing many key vitamins and minerals unavailable in meat.  And it is still true that the more alkalizing foods you consume, the better.

Phytase in Grains, Legumes, and Nuts

I downplayed the Cure Tooth Decay website earlier because it contains anti-vaxxer commentary, but this article on phytase looks good because it provides references. I plan on investigating these references later. This is important in part because I’m getting the impression that simply soaking oatmeal as I’ve been doing is a waste of time as far as phytase is concerned.

At a glance, I can tell that the section on oatmeal is more-or-less lifted straight from the WAPF website.

Soaking Legumes

These recommendations are from the WAPF site:

How does all this science translate into perfect beans? Soak legumes in plenty of water that has been brought to a simmer and poured over the beans; add about 1/4 cup of something acidic (lemon juice, vingear or whey) to black beans, lentils and fava beans but soak other types of beans (white beans, brown beans and dried peas) in plain water–preferably soft water or water with a pinch of baking soda added. You don’t need to worry about having the optimal pH if your diet contains animal foods and if the soaking is followed by a long slow cooking. Use the table below to determine approximate soaking times. For beans that require a long soaking time, you may wish to drain, rinse and add more water at least once during the process.

After soaking, drain the beans and rinse well, then add to a pot with more water and bring to a simmer. If digestibility is a problem for you, kombu added to the pot should take care of any pesky oligosaccharides still lurking. Cook those beans gently until completely tender.

Neutralizing Phytic Acid

Legume variety Optimal water pH Soaking time Best Soaking Medium
Black beans 5.5 18-24 hours Water with lemon juice, vinegar or whey added
Lentils 5.0 10 hours Water with lemon juice, vinegar or whey added
Fava beans 4.0 10 hours Water with lemon juice, vinegar or whey added
Dried and split peas 7.0 to 7.5 10 hours Plain soft water with pinch of baking soda
Brown, white & kidney beans 7.0 18-24 hours Plain soft water